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[134] Boldyrev A, Bulygina E, Leinsoo T, Petrushanko I, Tsubone S, Abe H. Protection of neuronal cells against reactive weaned oxygen species by carnosine and related compounds. Comparative Biochemistry and Physiology. B. 2004;**137**(1):81-88. DOI: 10.1016/

[135] Hipkiss A. Carnosine and its possible roles in nutrition and health. Advances in Food and Nutrition Research. 2009;**57**:87-154. DOI: 10.1016/S1043-4526(09)57003-9

[136] Trombley PQ, Hornung MS, Blakemore LJ. Interactions between carnosine and zinc and copper: Implications for neuromodulations and neuroprotection. Biochemistry

[137] Decker EA, Ivanov V, Zhu BZ, Frei B. Inhibition of low-density lipoprotein oxidation by carnosine and histidine. Journal of Agriculture and Food Chemistry. 2001;**49**(1):511-

[138] Hipkiss AR, Worthington VC, Himsworth DTJ, Herwig W. Protective effects of carnosine against protein modification mediated by malondialdehyde and hypochlorite.

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[140] Rayman MP. Selenium and human health. Lancet. 2012;**379**(9822):1256-1268. DOI:

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cmaj.101095

**Chapter 5**

**Provisional chapter**

**Feeding**

**Feeding**

Figen Kırkpınar and Zümrüt Açıkgöz

Figen Kırkpınar and Zümrüt Açıkgöz

http://dx.doi.org/10.5772/intechopen.78618

**Abstract**

sheep and goat

Overfeeding may be disastrous as underfeeding.

**1. Introduction**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

DOI: 10.5772/intechopen.78618

Animal nutrition and feed science are the main scientific promote for today's modern breeding and feed industries. Animal nutrition is the most important factor affecting performance, reproduction and products quality. Improving productivity through better nutrition is determined by some interrelated considerations such as the availability of nutrients, type of feeding system and the level of feeding management. Poor nutrition affects growth, reproduction and immune system. Besides, feed has financially the largest share in animal production, irrespective of species and production system. Feed accounts for 65–75% of total cost of livestock production. This chapter provides the fundamental concepts of animal nutrition a general awareness on nutrition and feeding of livestock (swine, poultry, beef and dairy cattle, sheep and goat). Besides, feed is financially the single most important element of animal production in most production system.

**Keywords:** digestive systems, feedstuffs, nutrition, swine, poultry, beef and dairy cattle,

Feed costs can be as high as 65–75% of the total production costs. The good quality feed also increases the incomes of producers. One way to reduce these costs is to ensure the animal has a balanced diet. A balanced diet is one that meets the nutritional needs requirements of the livestock, based on its age, gender and physiological stage. Adequate nutrients are essential for the metabolic function and health of any animal. Prolonged deficiency of nutrients would result in loss of condition and productive. Poor quality feeds may lead to a shortage of some dietary essentials or other factors may cause the development of serious nutritional diseases.

> © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

#### **Feeding Feeding**

#### Figen Kırkpınar and Zümrüt Açıkgöz Figen Kırkpınar and Zümrüt Açıkgöz

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.78618

**Abstract**

Animal nutrition and feed science are the main scientific promote for today's modern breeding and feed industries. Animal nutrition is the most important factor affecting performance, reproduction and products quality. Improving productivity through better nutrition is determined by some interrelated considerations such as the availability of nutrients, type of feeding system and the level of feeding management. Poor nutrition affects growth, reproduction and immune system. Besides, feed has financially the largest share in animal production, irrespective of species and production system. Feed accounts for 65–75% of total cost of livestock production. This chapter provides the fundamental concepts of animal nutrition a general awareness on nutrition and feeding of livestock (swine, poultry, beef and dairy cattle, sheep and goat). Besides, feed is financially the single most important element of animal production in most production system.

DOI: 10.5772/intechopen.78618

**Keywords:** digestive systems, feedstuffs, nutrition, swine, poultry, beef and dairy cattle, sheep and goat

#### **1. Introduction**

Feed costs can be as high as 65–75% of the total production costs. The good quality feed also increases the incomes of producers. One way to reduce these costs is to ensure the animal has a balanced diet. A balanced diet is one that meets the nutritional needs requirements of the livestock, based on its age, gender and physiological stage. Adequate nutrients are essential for the metabolic function and health of any animal. Prolonged deficiency of nutrients would result in loss of condition and productive. Poor quality feeds may lead to a shortage of some dietary essentials or other factors may cause the development of serious nutritional diseases. Overfeeding may be disastrous as underfeeding.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

On the other hand, the safety and quality of animal feedstuffs are also vital for preventing hazardous substances entering the food chain and affecting human health. Feedstuffs and additives, diet formulation and, in some cases, diet distribution have an influence on both animal well-being and the characteristics and composition of animal products as meat, milk or egg, and so on, for human consumption.

The main constraint to livestock development in many developing countries is the scarcity and inadequate quantity and quality of feed supply, poor quality and nutrient imbalance in many native pastures and crop residues, lack of or limited use of commercial concentrate feeds.

## **2. Feedstuffs and feed additives**

This part provides some details of the feedstuffs and feed additives that are fed to animals, including their main nutritional composition and function that need to be taken into account when they are used in animals diets. Feedstuffs are the edible materials, after ingestion by animals is capable of being digested, absorbed and utilised. The main components of feedstuffs are given in **Figure 1**. Feedstuffs consist of water and dry matter. The water (moisture) content of feedstuffs is very variable and can range from 60 g/kg (in concentrates) to 900 g/kg (in some root crops). Owing to this wide variation, it is generally preferred that the feedstuff composition is specified on dry matter basis. In this perspective, the nutrient contents of feedstuffs might be effectively compared [1].

**Figure 2.** Classification of feedstuffs.

**Class Characteristics**

as seed coats, pods, bran.

poultry by-products.

**Table 1.** Classes of feeds and characteristics.

Roughages Roughages are bulky feeds containing relatively large amounts of poorly digestible material. These

Fermentation uses nutrients and thus reduces nutritive content of the material. Concentrates Energy-rich feeds contain less than 18% crude fibre, less than 20% protein. The protein digestibility

industrial by-products, for example, wood molasses, fats and oils.

like thiamine, riboflavin, niacin, pantothenic acid, biotin, vitamin B<sup>6</sup>

K, S, Mg, Trace Elements: I, Mn, F, Co, B, Zn, Fe, Cu, M).

groups contain more than 18% crude fibre. They can be two major categories, namely dry and wet based on their moisture content. Wet roughages contain more than 75% moisture and include pasture, range plants and forages fed green, cultivated fodder crops, grasses legumes, tree leaves and silage/ haylage while dry roughages contain only 10–15% and include hays, straws, hulls and crop residues

Silages/haylages include ensiled forages. The process of ensiling plant materials under anaerobic conditions, which is a common storage method for feeds. The plant material undergoes a controlled fermentation that produces acids that then kill off bacteria, moulds and other destructive organisms.

ranges from 50 to 80%, but the protein quality is generally poor. These are fed to ruminants and cecal fermenters to increase the energy density of their diets, and to monogastrics as the primary source of energy. Examples of energy sources are: cereal grains, for example, corn, wheat, barley, oats, rye, sorghum, triticale; other grains, for example, buckwheat; grain milling by-products, for example, wheat bran, corn gluten meal; roots, tubers, for example, cassava, potatoes; food processing by-products, for example, molasses, bakery waste, citrus pulp, distillers and brewers by-products;

Protein supplements contain 20% or more of protein; some have high-energy contents as well from plant or animal origin. Examples of protein sources are: oilseed meals, for example, soybean, cottonseed, rapeseed, canola, linseed, peanut, safflower, sunflower; grain legumes, for example, beans, peas, lupines; single-cell protein, synthetic amino acids, non-protein nitrogen sources, for example, urea, biuret and by-pass proteins, for example, corn gluten meal for ruminants; animals proteins, for example, meat meal, fish meal, tankage, feather meal, bone meal, dried milk or products as whey,

Depending on the feeds used to balance a ration for the other nutrients, concentrated sources of vitamins and minerals may be needed. Some vitamin supplements include ensiled yeast, liver meal, fish oil, wheat germ oil and purified forms of individual vitamins (A, D, E, K, C and B vitamins

common mineral supplements include: salt (often trace mineralised), bone meal, oyster shell, calcium carbonate, limestone and fairly pure forms of other specific minerals (Major elements: Na, Ca, P, CL,

, vitamin B12 and folate). Some

Feeding

99

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Nutritional components of a feedstuff can greatly influence production performance of animals. The feed value of a feedstuff is a measure of its main nutritional components. For livestock, the feed value of any feedstuffs depends mainly on the concentration of energy (carbohydrates, fats, proteins and their digestibility), protein (including NPN and aspects of degradability), vitamins and minerals contents in the dry matter, special aspects (like keeping quality, availability, handling, taste, toxins, influence on sensory quality of meat, milk or egg etc.), physical aspects and price.

**Figure 1.** The main components of a feedstuff.

Feeding http://dx.doi.org/10.5772/intechopen.78618 99

**Figure 2.** Classification of feedstuffs.

On the other hand, the safety and quality of animal feedstuffs are also vital for preventing hazardous substances entering the food chain and affecting human health. Feedstuffs and additives, diet formulation and, in some cases, diet distribution have an influence on both animal well-being and the characteristics and composition of animal products as meat, milk

The main constraint to livestock development in many developing countries is the scarcity and inadequate quantity and quality of feed supply, poor quality and nutrient imbalance in many native pastures and crop residues, lack of or limited use of commercial concen-

This part provides some details of the feedstuffs and feed additives that are fed to animals, including their main nutritional composition and function that need to be taken into account when they are used in animals diets. Feedstuffs are the edible materials, after ingestion by animals is capable of being digested, absorbed and utilised. The main components of feedstuffs are given in **Figure 1**. Feedstuffs consist of water and dry matter. The water (moisture) content of feedstuffs is very variable and can range from 60 g/kg (in concentrates) to 900 g/kg (in some root crops). Owing to this wide variation, it is generally preferred that the feedstuff composition is specified on dry matter basis. In this perspective, the nutrient contents of feedstuffs

Nutritional components of a feedstuff can greatly influence production performance of animals. The feed value of a feedstuff is a measure of its main nutritional components. For livestock, the feed value of any feedstuffs depends mainly on the concentration of energy (carbohydrates, fats, proteins and their digestibility), protein (including NPN and aspects of degradability), vitamins and minerals contents in the dry matter, special aspects (like keeping quality, availability, handling, taste, toxins, influence on sensory quality of meat, milk or egg

or egg, and so on, for human consumption.

**2. Feedstuffs and feed additives**

might be effectively compared [1].

etc.), physical aspects and price.

**Figure 1.** The main components of a feedstuff.

trate feeds.

98 Animal Husbandry and Nutrition



cause lowered production and even death. For example, nitrite poisoning from some grasses and weeds, cyanide poisoning from immature sorghums and some weeds, alkaloid poisoning from immature some leguminous and copper toxicity. Feeds are classified according to the number of specific nutrients they supply. Two main classes of feedstuffs are roughages/forage and concentrate. In addition, feeds can be further subclassified as shown in **Figure 2** and

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Feed additives are used to increase feed conversion, improve the amount and quality of animal products in terms of hygienic quality and standards, protect animal health and reduced production costs. From the point of view of being able to control the effects of these substances on human health, it is very important that additives should be able to be determined in both feeds and final products. In recent years, animal production has been fundamental changes, particularly, European Union has brought some changes feed additives used feed industry, taking into account animal, human health and environment. A tendency to return to natural methods in animal production and consume healthy products has given rise to discussions concerning feed additives. At the same time, for example, because of problems resulting from the intensive use of antibiotics, the use of alternative feed additives has come to the fore.

Livestock has a tube-type digestive tract. This tube has different organs that play a specific role in the digestive process. Digestive system mechanically and chemically breaks down from complex macromolecules (lipid, polysaccharide and protein) into their component parts. These nutrients can be absorbed and used for energy, growth and maintenance of body tissues. There are three types of digestive tract in farm animals: monogastric, poultry and ruminant.

The digestive system of monogastric animals (dog, cat, swine, rabbit, horse, etc.) consists of mouth, oesophagus, stomach, small intestine, cecum, large intestine, anus and supportive organs (pancreas, liver and gall bladder). Digestion processes of swine are shown in **Table 3** [3–5].

Poultry (chicken, turkey, quail, goose, ducks, etc.) digestive system begins at the mouth/beak and ends at the cloaca and has several important organs in between [oesophagus, crop, stomach (proventriculus and gizzard), small intestine, cecum, large intestine]. Pancreas, liver and gall bladder are accessory organs in digestion. Digestion processes of poultry are summarised

Ruminant (polygastric) (cattle, sheep, goat, etc.) digestive system includes mouth, oesophagus, stomach (rumen, reticulum, omasum and abomasum), small intestine, cecum, large

characteristics in **Table 1**.

Categories of feed additives are shown in **Table 2**.

**3.1. Monogastric digestive system and digestion**

**3.2. Poultry digestive system and digestion**

**3.3. Ruminant digestive system and digestion**

in **Table 4** [6, 7].

**3. Digestive system and digestion**

**Table 2.** Categories of feed additives.

On the other hand, for example, production can be significantly restricted by a number of mineral and vitamin deficiencies, such as calcium, magnesium, phosphorus, copper, cobalt, vitamins A or D, and so on. In addition, excesses of particular substances in feedstuffs can cause lowered production and even death. For example, nitrite poisoning from some grasses and weeds, cyanide poisoning from immature sorghums and some weeds, alkaloid poisoning from immature some leguminous and copper toxicity. Feeds are classified according to the number of specific nutrients they supply. Two main classes of feedstuffs are roughages/forage and concentrate. In addition, feeds can be further subclassified as shown in **Figure 2** and characteristics in **Table 1**.

Feed additives are used to increase feed conversion, improve the amount and quality of animal products in terms of hygienic quality and standards, protect animal health and reduced production costs. From the point of view of being able to control the effects of these substances on human health, it is very important that additives should be able to be determined in both feeds and final products. In recent years, animal production has been fundamental changes, particularly, European Union has brought some changes feed additives used feed industry, taking into account animal, human health and environment. A tendency to return to natural methods in animal production and consume healthy products has given rise to discussions concerning feed additives. At the same time, for example, because of problems resulting from the intensive use of antibiotics, the use of alternative feed additives has come to the fore. Categories of feed additives are shown in **Table 2**.

## **3. Digestive system and digestion**

Livestock has a tube-type digestive tract. This tube has different organs that play a specific role in the digestive process. Digestive system mechanically and chemically breaks down from complex macromolecules (lipid, polysaccharide and protein) into their component parts. These nutrients can be absorbed and used for energy, growth and maintenance of body tissues. There are three types of digestive tract in farm animals: monogastric, poultry and ruminant.

## **3.1. Monogastric digestive system and digestion**

The digestive system of monogastric animals (dog, cat, swine, rabbit, horse, etc.) consists of mouth, oesophagus, stomach, small intestine, cecum, large intestine, anus and supportive organs (pancreas, liver and gall bladder). Digestion processes of swine are shown in **Table 3** [3–5].

#### **3.2. Poultry digestive system and digestion**

Poultry (chicken, turkey, quail, goose, ducks, etc.) digestive system begins at the mouth/beak and ends at the cloaca and has several important organs in between [oesophagus, crop, stomach (proventriculus and gizzard), small intestine, cecum, large intestine]. Pancreas, liver and gall bladder are accessory organs in digestion. Digestion processes of poultry are summarised in **Table 4** [6, 7].

#### **3.3. Ruminant digestive system and digestion**

On the other hand, for example, production can be significantly restricted by a number of mineral and vitamin deficiencies, such as calcium, magnesium, phosphorus, copper, cobalt, vitamins A or D, and so on. In addition, excesses of particular substances in feedstuffs can

**5.** Coccidiostats and histomonostats These substances that one or more of the functional groups,

**Categories Feed additives**

**a.** Preservatives **b.** Antioxidants **c.** Emulsifiers **d.** Stabilisers **e.** Thickeners **f.** Gelling agents **g.** Binders

**i.** Anticaking agents **j.** Acidity regulators **k.** Silage additives **l.** Denaturants

mycotoxins

**b.** Flavoring compounds

**d.** Urea and its derivatives

target feed materials

tive effect on the gut flora

**d.** Other zootechnical additives

intended to kill or inhibit protozoa

stances having similar effect **b.** Compounds of trace elements

**c.** Amino acids, their salts and analogues

**a.** Colorants

**3.** Nutritional additives **a.** Vitamins, pro-vitamins and chemically well-defined sub-

**h.** Substances for control ofradionucleide contamination

**m.** Substances for reduction of the contamination of feed by

**a.** Digestibility enhancers: substances which, when fed to animals, increase the digestibility of the diet, through action on

**b.** Gut flora stabilisers: micro-organisms or other chemically defined substances, which, when fed to animals, have a posi-

**c.** Substances which favourably affect the environment

**1.** Technological additives: any substance added to

**2.** Sensory additives: any substance, the addition of which to feed improves or changes the organoleptic properties of the feed, or the visual characteristics

**4.** Zootechnical additives: any additive used to affect favourably the performance of animals in good health or used to affect favourably the

of the food derived from animals

environment

EC, No 1831/2003 [2].

**Table 2.** Categories of feed additives.

feed for a technological purpose

100 Animal Husbandry and Nutrition

Ruminant (polygastric) (cattle, sheep, goat, etc.) digestive system includes mouth, oesophagus, stomach (rumen, reticulum, omasum and abomasum), small intestine, cecum, large


**Organs Secretion/Enzyme Function**

Small intestine Pancreatic amylase and intestinal

**Organs Secretion/Enzyme Function**

**Table 4.** Digestive processes of poultry.

sucrase)

phospholipase

Gizzard — Mechanically grinds and mixes of

disaccharidases (maltase, isomaltase,

Pancreatic lipase, cholesterol esterase,and

Cecum — Ferments undigested nutrients by

Large intestine — Absorbs water and minerals and

Cloaca — Serves as common opening of the

Mouth — Obtains and chews feeds, releases of fermentation

Saliva Moistens feed to aid in swallowing

Rumen Microbial enzymes Degradation of carbohydrates, protein and lipids,

Abomasum HCL Decreases pH, denatures protein, activates pepsinogen,

Pepsins Hydrolyse microbial and by-pass proteins

Lipase Hydrolyses lipid (particularly in milk-fed young ruminant) Rennins Coagulate milk protein (casein) in postnatal period

Oesophagus — Transports feed from mouth to rumen

Reticulum — Continues ruminal fermentation

Omasum — Grinds feeds and absorbs water and VFAs

Pancreatic (trypsin,chymotrypsins, carboxypeptidases, elastase) and intestinal (aminopeptidases, dipeptidases, tripeptidases) proteases

Bile acids Emulsify lipid

Pancreatic and intestinal nucleases Hydrolyse nucleic acids — Absorbs nutrients

gases (mostly CO2

and biohydrogenation

kills bacteria

ingesta and continues enzymatic

http://dx.doi.org/10.5772/intechopen.78618

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103

digestion

Hydrolyse starch

Hydrolyse lipid

Hydrolyse protein

microbes

systems

and CH4

synthesis of microbial protein/lipid and some vitamins (K and B-complex), absorption of VFAs and ammonia,

storages waste

digestive, reproductive and urinary

) and ruminates

**Table 3.** Digestive processes of swine.



**Table 4.** Digestive processes of poultry.

**Organs Secretion/Enzyme Function**

Pancreatic amylase and intestinal disaccharidases

Pancreatic (trypsin,chymotrypsins, carboxypeptidases, elastase) and intestinal (aminopeptidases, dipeptidases,

Anus — Removes faeces

**Organs Secretion/Enzyme Function** Mouth/beak(No lips and teeth) — Obtains feed

Oesophagus — Carries feed from mouth to crop Crop Mucus Lubricates and softens feed Proventriculus HCL Decreases pH, denatures protein,

(maltase, isomaltase, sucrase, lactase)

tripeptidases) proteases

**Table 3.** Digestive processes of swine.

Small intestine

102 Animal Husbandry and Nutrition

Large intestine

Mouth Teeth Mechanically reduces particle size and

Pepsins Begin protein digestion

Bile acids Emulsify lipid Pancreatic lipase, cholesterol esterase,and phospholipase Hydrolyse lipid

Pancreatic and intestinal nucleases Hydrolyse nucleic acids — Absorbs nutrients Cecum — Ferments undigested nutrients by

Lipase Hydrolyses lipid (particularly in milk-fed

— Absorbs water, volatile fatty acids (VFAs)

Saliva Lubricates and softens feed Salivary amylase (ptyalin) Begins starch digestion

Pepsins Begin protein digestion

Lipase Begins lipid digestion (particularly

raptors)

Rennins Coagulate milk protein (casein) in

Saliva Lubricates and softens feed Salivary amylase (ptyalin) Begins starch digestion Oesophagus — Carries feed from mouth to stomach Stomach HCL Decreases pH, denatures protein, activates

increases surface area

pepsinogen, kills bacteria

young swine)

postnatal period

Hydrolyse starch

Hydrolyse proteins

and minerals and forms faeces

activates pepsinogen, kills bacteria

in carnivore avian species such as

microbes



Energy requirements are expressed as kilocalories (kcal) of digestible energy (DE), metabolizable energy (ME), or net energy (NE). DE and ME values are most commonly used; however, NE has been preferred in the industry recently. Energy requirements of swine are basically influenced by their body weight, body weight gain, genetic capacity, lean tissue growth or milk production and the environmental temperature. One of the largest expenses for swine diets is energy. Carbohydrates (sugar, starch and fibre) from cereal grains (corn, sorghum, wheat, barley, triticale, oats, rye) and their by-products and their by-products provide most of the energy in typical swine diets so utilising lower cost alternative feedstuffs or forages for swine can use to lower feed costs. Fats and oils are excellent energy sources in swine diets. Protein sources also provide a significant amount of energy in swine diets. Protein commonly contributes 15–20% of the total energy in the diet. The amount of feed consumed by swine is controlled by the energy content of the diet fed *ad-libitum*. The diet contains high energy and low fibre generally. Protein and amino acids are required for maintenance, muscle growth, development of foetuses, nutrition of gestating and lactating sows both supporting tissue and milk production. Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine are essential amino acids for swine. The essential amino acids of greatest practical importance

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in diet formulation especially lysine, tryptophan, threonine and methionine.

should be legal restrictions.

Corn is markedly deficient in lysine and tryptophan. Sorghum, barley and wheat are low in lysine and threonine. The first limiting amino acid in soybean meal is methionine. Animal protein sources are good for supplemental essential amino acids. Soybean meal is basic source of amino acids, also used alternative plant origin sources as cottonseed meal, canola meal, sunflower meal and peanut meal, animal sources as meat and bone meal, fish meal, poultry meal, spray-dried whey, egg and blood; grain by-products dried distillers and corn gluten meal or synthetic amino acids. Swine require linoleic acid and other polyunsaturated fatty acids. The requirement is generally met by natural dietary ingredients from oil in corn. Linoleic acid is considered the dietary essential fatty acid so the longer chain fatty acids can be synthesised from the linoleic acid [11]. Swine should have free and convenient access to good quality water. Minerals and vitamins are required for maintenance, metabolic function, development of tissues, health and growth. Mineral and vitamin premixes or complete manufactured supplements are commercially available. Feed additives have commonly been added to swine diets to promote growth. The levels of feed additives and withdrawal requirements

The typical diet containing 3300–3400 kcal of ME/kg based on corn-soybean meal diet for the various weights of growing swine as estimated by the NRC [10]. Feed intakes may be slightly higher for barrows and slightly less for gilts. If the diet containing 3300 kcal of ME/ kg based on corn-soybean meal diet for gestating and lactating (during a 21-day lactation) gilts and sows, it provides sufficient energy at the optimum feeding level. However, higher feeding levels will be needed to meet the sow's daily energy requirement used oats, alfalfa meal or other energy diluents on gestation diets. High-energy diets recommended fed *adlibitum* to sows during lactation. If this is not possible, sows should be hand-fed three times daily. The requirement of energy depends on the number of swine nursed, weight gain and milk production. If sows have lost excess weight and feed consumption is low significantly, there is recommended additional fat approximately 3–6% to lactation diet. Sows need diets

**Table 5.** Digestive processes of ruminant.

intestine, anus and supportive organs (pancreas, liver and gall bladder). Digestion processes of ruminant are given in **Table 5** [5, 8, 9].

## **4. Nutrition and feeding of swine**

Swine have a long history of providing food for people. Swine require a number of essential nutrients to meet their needs for maintenance, growth, reproduction, lactation and other living functions. However, factors such as growth rate, genetic variation, gender, stage of gestation, feed quality and intake, availability of nutrients in feedstuffs, energy density of the diets, disease, environment temperature, management factors, for example, crowding and other stress factors may change also increase the needed level of nutrients for optimal performance. Performance of weanling, growing and finishing swine, gestating and lactating sows is related to the quality of the diet and the amount consumed daily. The National Research Council (NRC) [10] provides estimates of the amounts of energy, protein, amino acids, minerals and vitamins for various classes of swine under average conditions. Although nutritionists, feed manufacturers and producers may wish to include higher levels of some nutrients than those listed by the NRC to ensure adequate intake of nutrients and for a certain amount of safety commercially, therefore the NRC values are thought of as minimum requirements without any safety allowances. In addition, the dietary concentrations listed in the NRC tables are based on a given amount of feed intake, if feed intake is less than the amount listed, dietary concentration may need to be increased to guarantee an adequate daily intake of the nutrients. In general, swine require six classes of nutrients: energy (carbohydrates, fats), protein (amino acids), minerals, vitamins and water.

Energy requirements are expressed as kilocalories (kcal) of digestible energy (DE), metabolizable energy (ME), or net energy (NE). DE and ME values are most commonly used; however, NE has been preferred in the industry recently. Energy requirements of swine are basically influenced by their body weight, body weight gain, genetic capacity, lean tissue growth or milk production and the environmental temperature. One of the largest expenses for swine diets is energy. Carbohydrates (sugar, starch and fibre) from cereal grains (corn, sorghum, wheat, barley, triticale, oats, rye) and their by-products and their by-products provide most of the energy in typical swine diets so utilising lower cost alternative feedstuffs or forages for swine can use to lower feed costs. Fats and oils are excellent energy sources in swine diets. Protein sources also provide a significant amount of energy in swine diets. Protein commonly contributes 15–20% of the total energy in the diet. The amount of feed consumed by swine is controlled by the energy content of the diet fed *ad-libitum*. The diet contains high energy and low fibre generally. Protein and amino acids are required for maintenance, muscle growth, development of foetuses, nutrition of gestating and lactating sows both supporting tissue and milk production. Arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine are essential amino acids for swine. The essential amino acids of greatest practical importance in diet formulation especially lysine, tryptophan, threonine and methionine.

Corn is markedly deficient in lysine and tryptophan. Sorghum, barley and wheat are low in lysine and threonine. The first limiting amino acid in soybean meal is methionine. Animal protein sources are good for supplemental essential amino acids. Soybean meal is basic source of amino acids, also used alternative plant origin sources as cottonseed meal, canola meal, sunflower meal and peanut meal, animal sources as meat and bone meal, fish meal, poultry meal, spray-dried whey, egg and blood; grain by-products dried distillers and corn gluten meal or synthetic amino acids. Swine require linoleic acid and other polyunsaturated fatty acids. The requirement is generally met by natural dietary ingredients from oil in corn. Linoleic acid is considered the dietary essential fatty acid so the longer chain fatty acids can be synthesised from the linoleic acid [11]. Swine should have free and convenient access to good quality water. Minerals and vitamins are required for maintenance, metabolic function, development of tissues, health and growth. Mineral and vitamin premixes or complete manufactured supplements are commercially available. Feed additives have commonly been added to swine diets to promote growth. The levels of feed additives and withdrawal requirements should be legal restrictions.

intestine, anus and supportive organs (pancreas, liver and gall bladder). Digestion processes

— Absorbs water, VFAs and minerals and forms faeces

Hydrolyse starch escaping ruminal digestion

Hydrolyse microbial and by-pass proteins

Hydrolyse lipid

Swine have a long history of providing food for people. Swine require a number of essential nutrients to meet their needs for maintenance, growth, reproduction, lactation and other living functions. However, factors such as growth rate, genetic variation, gender, stage of gestation, feed quality and intake, availability of nutrients in feedstuffs, energy density of the diets, disease, environment temperature, management factors, for example, crowding and other stress factors may change also increase the needed level of nutrients for optimal performance. Performance of weanling, growing and finishing swine, gestating and lactating sows is related to the quality of the diet and the amount consumed daily. The National Research Council (NRC) [10] provides estimates of the amounts of energy, protein, amino acids, minerals and vitamins for various classes of swine under average conditions. Although nutritionists, feed manufacturers and producers may wish to include higher levels of some nutrients than those listed by the NRC to ensure adequate intake of nutrients and for a certain amount of safety commercially, therefore the NRC values are thought of as minimum requirements without any safety allowances. In addition, the dietary concentrations listed in the NRC tables are based on a given amount of feed intake, if feed intake is less than the amount listed, dietary concentration may need to be increased to guarantee an adequate daily intake of the nutrients. In general, swine require six classes of nutrients: energy (carbohydrates, fats),

of ruminant are given in **Table 5** [5, 8, 9].

**Table 5.** Digestive processes of ruminant.

**Organs Secretion/Enzyme Function**

disaccharidases (maltase, isomaltase, lactase)

Pancreatic lipase, cholesterol esterase,and

Anus Removes faeces

Pancreatic (trypsin, chymotrypsins, carboxypeptidases, elastase) and intestinal (aminopeptidases, dipeptidases,

Bile acids Emulsify lipid

Pancreatic and intestinal nucleases Hydrolyse nucleic acids — Absorbs nutrients Cecum — Further microbial fermentation

Pancreatic amylase and intestinal

phospholipase

tripeptidases) proteases

Small intestine

104 Animal Husbandry and Nutrition

Large intestine

**4. Nutrition and feeding of swine**

protein (amino acids), minerals, vitamins and water.

The typical diet containing 3300–3400 kcal of ME/kg based on corn-soybean meal diet for the various weights of growing swine as estimated by the NRC [10]. Feed intakes may be slightly higher for barrows and slightly less for gilts. If the diet containing 3300 kcal of ME/ kg based on corn-soybean meal diet for gestating and lactating (during a 21-day lactation) gilts and sows, it provides sufficient energy at the optimum feeding level. However, higher feeding levels will be needed to meet the sow's daily energy requirement used oats, alfalfa meal or other energy diluents on gestation diets. High-energy diets recommended fed *adlibitum* to sows during lactation. If this is not possible, sows should be hand-fed three times daily. The requirement of energy depends on the number of swine nursed, weight gain and milk production. If sows have lost excess weight and feed consumption is low significantly, there is recommended additional fat approximately 3–6% to lactation diet. Sows need diets containing 16–18% or more crude protein (minimum of 0.9% lysine) [12]. If energy intake is sufficient, high protein diets will minimise weight loss in sows during lactation. Newborn swine should be consumed colostrum during the first 24 h post-farrowing. If the sow is slow in coming into milk, commercial milk replacers can be used. A palatable swine starter diet should be provided beginning at 2–3 weeks if pigs are weaned later than 3–4 weeks of age [12]. It is recommended that the starter diet contains dried whey and/or lactose, dried blood products and a high level of lysine. The nutritional requirements of growing and finishing swine met by full feeding program. Besides, restricted feeding may improve carcass quality of finishing pigs. The nutrient composition of ingredients should be known when formulating diets to meet the recommended nutrient requirements of swine. Compositions of ingredients commonly used in swine diets are given in various tables.

Unlike broiler sector, the laying period of modern brown and white layers has prolonged and they may be kept up to 80 weeks in production, without moulting. During the first half of the rearing period, feeding program needs to focus on an optimal supply of digestible amino acids and minerals to ensure the basic growth of the inner organs, muscles and skeleton. These physiological developments of the pullet continue at a slower rate in the second half of the rearing phase therefore protein and amino acids requirements reduce. On the other hand, it is recommended to increase dietary fibre level (5–6%) in this stage for crop, gizzard and intestinal development. The pullet is started to feed with pre-lay diet about 2 weeks prior to first egg (after 15 weeks of age). On reaching about 5% egg production, the layer diet should be used instead of the pre-layer diet. Common mistakes are feeding pre-lay diet too early or for too long, which may result in poor peak rate of lay [19]. The pre-lay diet contains 2–2.5% calcium while the other nutrients are similar to a layer diet. The purpose of using the pre-lay

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Daily feed intake of layers is relatively low between the onset of egg production and peak egg production (approximately 32 weeks of age). Nevertheless, nutrient requirements increase during this critical stage because bird continues to grow, and the size and production of egg rises. Therefore, the first layer diet should be fairly concentrated. The nutrient requirements of laying hens depend on the daily egg mass in post peaking period. The best way of ensuring proper nutrition is the use of a phase feeding system matched to the changes in nutrient

Layer diets have higher calcium content than per-lay diet since egg weight and production increase for peaking period and the hens' ability to absorb calcium from the diet diminishes for post peaking period. The eggshell contains about 2.2 g calcium. Adequate dietary levels of calcium should be provided to ensure proper calcification of the eggshell. The source and particle size of calcium used in laying hen diets are also of importance. To maintain adequate calcium blood level overnight when feed is not consumed and calcium requirement is high due to eggshell formation, a laying hen's diet needs to include coarse limestone and/or oyster

For additional information, see nutrient requirements of broilers and egg layers [22–24]. The NRC [22] and Aviagen Ross 308 [23] estimates of nutrient requirements and essential micronutrients of broilers and NRC [22] and Lohmann LSL-CLASSIC [24] estimates of nutrient

Feed accounts for over 70% of the cost of beef cattle production generally. If the feeding is efficient, the cost of production is reduced while the productivity and profitability of beef production increases. Grazing amount and management are important to reduce production costs. Cattle are ruminant animals and beneficial relationship with their rumen microorganisms (bacteria, protozoa, fungi) to help those digesting fibrous feedstuffs. Beef cattle require nutrients to meet their needs for maintenance, physical activity, growth, milk production, reproduction and health. These requirements of cattle may change age, sex, breed and production cycle. If mature and young growing cattle consume sufficient high-quality pasture

**6. Nutrition and feeding of large ruminants: Beef and dairy cattle**

diets is to build up the medullary reserves [20].

requirements [20].

shell with lower solubility [21].

requirements and essential micronutrients of egg layers.

For additional information, see nutrient requirements of swine [10]. The NRC estimates of nutrient requirements for various body weights of swine, requirements for gestating and lactating sows, expressed as dietary concentrations are given in various tables. These nutritional macro and trace minerals and vitamins play many important metabolic functions in the body. The estimated dietary requirements for the essential micronutrients are given by NRC in Tables [10].

## **5. Nutrition and feeding of poultry**

Over recent decades, broiler and layer performances have considerably improved as the result of the advancements of breeding, feeding, disease control, housing and husbandry technologies. Nutrient requirements of the modern layer and broiler strains have changed because of their high production potential.

Nowadays, the fattening period varies between 35 and 42 days in conventional broiler production sector. In this period, it is used different diets (starter, grower and finisher) due to the alteration of nutrient requirements of broiler with age. Not only age, all factors affecting nutrient requirements should be considered together while diet density is adjusted. Corn and soybean meal are used as basal feed ingredients in broiler diets. In corn-soybean meal diet, methionine is the first limiting amino acid followed by lysine. All diets containing low crude fibre are provided adlibitum to birds throughout the production period.

Recently, it is recommended that natural growth promoters, such as organic acids, probiotics, prebiotics, synbiotics, essential oils, enzymes etc., are supplemented to diets to optimise performance. The main purpose of using these feed additives is to maintain and enhance gastrointestinal health [13]. In this context, it is currently being examined the usable potential of various bee products (propolis, pollen, etc.) as natural growth enhancers [14, 15]. Moreover, due to shortening slaughter age, pre-hatch (last phase of incubation) and immediate posthatch periods in which occur many significant physiological and metabolic changes affecting broiler performance have become increasingly important. Therefore, early feeding practices such as in-ovo feeding, hatching supplement (hydrated nutritional supplement) and prestarter diets are suggested to apply in these periods in order to achieve maximum growth performance of fast-growing broilers [16–18].

Unlike broiler sector, the laying period of modern brown and white layers has prolonged and they may be kept up to 80 weeks in production, without moulting. During the first half of the rearing period, feeding program needs to focus on an optimal supply of digestible amino acids and minerals to ensure the basic growth of the inner organs, muscles and skeleton. These physiological developments of the pullet continue at a slower rate in the second half of the rearing phase therefore protein and amino acids requirements reduce. On the other hand, it is recommended to increase dietary fibre level (5–6%) in this stage for crop, gizzard and intestinal development. The pullet is started to feed with pre-lay diet about 2 weeks prior to first egg (after 15 weeks of age). On reaching about 5% egg production, the layer diet should be used instead of the pre-layer diet. Common mistakes are feeding pre-lay diet too early or for too long, which may result in poor peak rate of lay [19]. The pre-lay diet contains 2–2.5% calcium while the other nutrients are similar to a layer diet. The purpose of using the pre-lay diets is to build up the medullary reserves [20].

containing 16–18% or more crude protein (minimum of 0.9% lysine) [12]. If energy intake is sufficient, high protein diets will minimise weight loss in sows during lactation. Newborn swine should be consumed colostrum during the first 24 h post-farrowing. If the sow is slow in coming into milk, commercial milk replacers can be used. A palatable swine starter diet should be provided beginning at 2–3 weeks if pigs are weaned later than 3–4 weeks of age [12]. It is recommended that the starter diet contains dried whey and/or lactose, dried blood products and a high level of lysine. The nutritional requirements of growing and finishing swine met by full feeding program. Besides, restricted feeding may improve carcass quality of finishing pigs. The nutrient composition of ingredients should be known when formulating diets to meet the recommended nutrient requirements of swine. Compositions of ingredients

For additional information, see nutrient requirements of swine [10]. The NRC estimates of nutrient requirements for various body weights of swine, requirements for gestating and lactating sows, expressed as dietary concentrations are given in various tables. These nutritional macro and trace minerals and vitamins play many important metabolic functions in the body. The estimated dietary requirements for the essential micronutrients are given by NRC

Over recent decades, broiler and layer performances have considerably improved as the result of the advancements of breeding, feeding, disease control, housing and husbandry technologies. Nutrient requirements of the modern layer and broiler strains have changed because of

Nowadays, the fattening period varies between 35 and 42 days in conventional broiler production sector. In this period, it is used different diets (starter, grower and finisher) due to the alteration of nutrient requirements of broiler with age. Not only age, all factors affecting nutrient requirements should be considered together while diet density is adjusted. Corn and soybean meal are used as basal feed ingredients in broiler diets. In corn-soybean meal diet, methionine is the first limiting amino acid followed by lysine. All diets containing low crude fibre are provided adlibitum to birds throughout the produc-

Recently, it is recommended that natural growth promoters, such as organic acids, probiotics, prebiotics, synbiotics, essential oils, enzymes etc., are supplemented to diets to optimise performance. The main purpose of using these feed additives is to maintain and enhance gastrointestinal health [13]. In this context, it is currently being examined the usable potential of various bee products (propolis, pollen, etc.) as natural growth enhancers [14, 15]. Moreover, due to shortening slaughter age, pre-hatch (last phase of incubation) and immediate posthatch periods in which occur many significant physiological and metabolic changes affecting broiler performance have become increasingly important. Therefore, early feeding practices such as in-ovo feeding, hatching supplement (hydrated nutritional supplement) and prestarter diets are suggested to apply in these periods in order to achieve maximum growth

commonly used in swine diets are given in various tables.

**5. Nutrition and feeding of poultry**

performance of fast-growing broilers [16–18].

their high production potential.

in Tables [10].

106 Animal Husbandry and Nutrition

tion period.

Daily feed intake of layers is relatively low between the onset of egg production and peak egg production (approximately 32 weeks of age). Nevertheless, nutrient requirements increase during this critical stage because bird continues to grow, and the size and production of egg rises. Therefore, the first layer diet should be fairly concentrated. The nutrient requirements of laying hens depend on the daily egg mass in post peaking period. The best way of ensuring proper nutrition is the use of a phase feeding system matched to the changes in nutrient requirements [20].

Layer diets have higher calcium content than per-lay diet since egg weight and production increase for peaking period and the hens' ability to absorb calcium from the diet diminishes for post peaking period. The eggshell contains about 2.2 g calcium. Adequate dietary levels of calcium should be provided to ensure proper calcification of the eggshell. The source and particle size of calcium used in laying hen diets are also of importance. To maintain adequate calcium blood level overnight when feed is not consumed and calcium requirement is high due to eggshell formation, a laying hen's diet needs to include coarse limestone and/or oyster shell with lower solubility [21].

For additional information, see nutrient requirements of broilers and egg layers [22–24]. The NRC [22] and Aviagen Ross 308 [23] estimates of nutrient requirements and essential micronutrients of broilers and NRC [22] and Lohmann LSL-CLASSIC [24] estimates of nutrient requirements and essential micronutrients of egg layers.

## **6. Nutrition and feeding of large ruminants: Beef and dairy cattle**

Feed accounts for over 70% of the cost of beef cattle production generally. If the feeding is efficient, the cost of production is reduced while the productivity and profitability of beef production increases. Grazing amount and management are important to reduce production costs. Cattle are ruminant animals and beneficial relationship with their rumen microorganisms (bacteria, protozoa, fungi) to help those digesting fibrous feedstuffs. Beef cattle require nutrients to meet their needs for maintenance, physical activity, growth, milk production, reproduction and health. These requirements of cattle may change age, sex, breed and production cycle. If mature and young growing cattle consume sufficient high-quality pasture as mixed grasses and legumes, they meet nutrients for maintenance and growth. However, pasture quality will depend on many factors, including geographic location, soil structure and environmental conditions as temperature, humidity, precipitation, type of grass and/ or legume, grazing management. The negative harvested condition may be so reduced in nutritive value particularly energy, protein, phosphorus and β-carotene that they are suitable only for a maintenance ration for adult cattle. Such feedstuffs should be supplemented with good quality concentrate, vitamin-mineral mixture, and feed additives if used for any other purposes. Beef cattle except for calves due to pre-ruminant can meet their maintenance energy requirements from good quality forages and roughages. Additional energy sources may be necessary for production. Cattle should be fed an adequate ration may receive the recommended nutrients for optimal performance, reproduction, cow and calf health, and growth of all classes of cattle.

Since the cow herd is still growing, as well as producing a calf, first-calf heifers should receive high-quality forage and protein-energy supplement. Calves graze forage and suckle cows for several months. At 3–4 weeks of age, they begin to graze forage, which during the next few months becomes their major nutrients source [28]. A program of management, which provides energy feeds other than milk, plus grass or hay usually, is defined as a creep feeding arrangement. Creep feeding usually results in increased calf gain during its suckling period. Creep feeding may be expected to make a difference in calf performance at almost any time of the year, but the greatest benefit may be expected when pasture or hay is of less than optimal quality and quantity [29]. Creep feed should be based on grain and protein supplement. Postweaning calves and replacement heifers feed good quality forage free choice. Supplement with grain and protein supplement as necessary to produce desired level body weight gain. Weaned calves may be raised on roughage for a year or more before entering the feedlot, or they may enter the feedlot directly after weaning [28]. Stocker growth is nourished, normally, with a preponderance of roughages, balanced with adequate protein, minerals and vitamins [30].

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Nutrient requirements of the various physiological conditions of beef and dairy cattle have been given by NRC. Nutrient requirements of pregnant replacement heifers, beef cows, growing bulls and large-breed dairy cattle are given by NRC in various tables [31, 32]. For additional information, see Nutrient Requirements of Beef Cattle [31] and Nutrient Requirements

Nutrition largely affects flock reproduction, milk production and growth in ruminants. Sheep and goat should be fed according to their nutritional needs [33, 34]. Many factors affect their nutrient requirements such as breed, age, body weight, physiological stage and yield level.

The digestive efficiency of sheep, goat and cattle is similar [35]. In general, goat is considered better browsers than sheep, has a higher voluntary feed intake and can digest fibre more

The digestive processes of neonate lamb and kid having undeveloped pre-stomach (rumen, reticulum and omasum) are very similar to those of monogastric animals. They are unable to digest ordinary carbohydrates except for lactose or grain-based feeds. The first meal of newborn is colostrum providing all nutrients and antibodies. By feeding on dry feeds (good quality roughage and concentrates), rumen becomes inoculated with microorganisms. As the microbes multiply and begin to digest feed, they stimulate the growth and development of

After adequate colostrum feeding, lamb/kid may be raised on sheep/goat milk (natural rearing) or milk replacer (artificial rearing). For various reasons such as inadequate milk production, higher milk price, reducing feed costs, and so on, producers may prefer to use artificial rearing. In both rearing system, it is recommended that liquid food feeding continues until lamb/kid weight reaches at least 10 kg. The composition of a good replacer for lamb is as follows: 22–24% crude protein, 25–35% ether extract, less than 1% crude fibre, 5–8% ash and 22–25% lactose [41].

the pre-stomach [40]. Lamb/kid's rumen is usually functional at 45–60 days old ages.

**7. Feeding and nutrition of small ruminants: Sheep and goat**

efficiently, particularly when fed low or medium-quality diets [36–39].

of Dairy Cattle [32].

Protein requirements for cattle are stated in terms of metabolizable protein is defined as the true protein absorbed by the small intestine and is composed of rumen undegradable protein (RUP) often has been called "bypass" protein and microbial crude protein (MCP). A portion of the feed protein is used by microorganisms as bacteria and protozoa that use the protein to manufacture microbial proteins. Protein supply to rumen microbes is expressed in terms of rumen degradable (RDP). The metabolizable protein used for maintenance and production. Urea and other sources of non-protein nitrogen (NPN) are used commonly in commercial protein supplements to supply one-third or more of the total nitrogen requirement[25]. Vitamin K and the B complex vitamins are synthesised in sufficient amounts by the ruminalmicroflora and vitamin C is synthesised in the tissues of all cattle in normal condition. Beef and dairy cattle have similar mineral elements requirements in qualitatively except for some exceptions. The salt (NaCl) requirement for cattle is quite low. Water should be free access for cattle. Many factors, including body temperature, body weight, growth, reproduction, lactation, digestion, metabolism, excretion affect water consumption and restricting water intake decreases performance.

Lactation is a major physiological and biochemical undertaking. The yield and composition of milk are affected by many factors such as species, breed, strain within the breed, age and stage of lactation. The efficiencies of metabolizable energy utilisation for maintenance and milk production are concerned with the energy contents of the diet and are very similar. High energy intakes must include a certain level of roughage in the diet if an acceptable rumen fermentation is to be maintained and problems of acidosis, reduced intake and low-fat milk are to be avoided [1]. Lactating dietary requirements differ from non-lactating ones with required higher levels of energy, nearly doubled levels of protein, calcium and phosphorus, but no change in vitamin A [26]. It is very important to regulate the amount and quality of concentrate during lactation. With this arrangement, nutrient requirements should be met adequately as well as no way should the animal be allowed to become too fat. Otherwise, production performance can lower in mid and late lactation. At the same time, feeding should be economical. Especially in early lactation period, at least 30% of the total ration should consist of roughage. Protein levels of concentrates are another important consideration during the different stages of lactation. Extra digestible crude protein (10–15%) would be beneficial for early lactation period, and it should be preferred wider digestible crude protein/energy ratio for milk production during the later phase of lactation cycle with inclusion of dry period [27].

Since the cow herd is still growing, as well as producing a calf, first-calf heifers should receive high-quality forage and protein-energy supplement. Calves graze forage and suckle cows for several months. At 3–4 weeks of age, they begin to graze forage, which during the next few months becomes their major nutrients source [28]. A program of management, which provides energy feeds other than milk, plus grass or hay usually, is defined as a creep feeding arrangement. Creep feeding usually results in increased calf gain during its suckling period. Creep feeding may be expected to make a difference in calf performance at almost any time of the year, but the greatest benefit may be expected when pasture or hay is of less than optimal quality and quantity [29]. Creep feed should be based on grain and protein supplement. Postweaning calves and replacement heifers feed good quality forage free choice. Supplement with grain and protein supplement as necessary to produce desired level body weight gain. Weaned calves may be raised on roughage for a year or more before entering the feedlot, or they may enter the feedlot directly after weaning [28]. Stocker growth is nourished, normally, with a preponderance of roughages, balanced with adequate protein, minerals and vitamins [30].

as mixed grasses and legumes, they meet nutrients for maintenance and growth. However, pasture quality will depend on many factors, including geographic location, soil structure and environmental conditions as temperature, humidity, precipitation, type of grass and/ or legume, grazing management. The negative harvested condition may be so reduced in nutritive value particularly energy, protein, phosphorus and β-carotene that they are suitable only for a maintenance ration for adult cattle. Such feedstuffs should be supplemented with good quality concentrate, vitamin-mineral mixture, and feed additives if used for any other purposes. Beef cattle except for calves due to pre-ruminant can meet their maintenance energy requirements from good quality forages and roughages. Additional energy sources may be necessary for production. Cattle should be fed an adequate ration may receive the recommended nutrients for optimal performance, reproduction, cow and calf health, and

Protein requirements for cattle are stated in terms of metabolizable protein is defined as the true protein absorbed by the small intestine and is composed of rumen undegradable protein (RUP) often has been called "bypass" protein and microbial crude protein (MCP). A portion of the feed protein is used by microorganisms as bacteria and protozoa that use the protein to manufacture microbial proteins. Protein supply to rumen microbes is expressed in terms of rumen degradable (RDP). The metabolizable protein used for maintenance and production. Urea and other sources of non-protein nitrogen (NPN) are used commonly in commercial protein supplements to supply one-third or more of the total nitrogen requirement[25]. Vitamin K and the B complex vitamins are synthesised in sufficient amounts by the ruminalmicroflora and vitamin C is synthesised in the tissues of all cattle in normal condition. Beef and dairy cattle have similar mineral elements requirements in qualitatively except for some exceptions. The salt (NaCl) requirement for cattle is quite low. Water should be free access for cattle. Many factors, including body temperature, body weight, growth, reproduction, lactation, digestion, metabolism,

excretion affect water consumption and restricting water intake decreases performance.

Lactation is a major physiological and biochemical undertaking. The yield and composition of milk are affected by many factors such as species, breed, strain within the breed, age and stage of lactation. The efficiencies of metabolizable energy utilisation for maintenance and milk production are concerned with the energy contents of the diet and are very similar. High energy intakes must include a certain level of roughage in the diet if an acceptable rumen fermentation is to be maintained and problems of acidosis, reduced intake and low-fat milk are to be avoided [1]. Lactating dietary requirements differ from non-lactating ones with required higher levels of energy, nearly doubled levels of protein, calcium and phosphorus, but no change in vitamin A [26]. It is very important to regulate the amount and quality of concentrate during lactation. With this arrangement, nutrient requirements should be met adequately as well as no way should the animal be allowed to become too fat. Otherwise, production performance can lower in mid and late lactation. At the same time, feeding should be economical. Especially in early lactation period, at least 30% of the total ration should consist of roughage. Protein levels of concentrates are another important consideration during the different stages of lactation. Extra digestible crude protein (10–15%) would be beneficial for early lactation period, and it should be preferred wider digestible crude protein/energy ratio for milk production during the later phase of lactation cycle with inclusion of dry period [27].

growth of all classes of cattle.

108 Animal Husbandry and Nutrition

Nutrient requirements of the various physiological conditions of beef and dairy cattle have been given by NRC. Nutrient requirements of pregnant replacement heifers, beef cows, growing bulls and large-breed dairy cattle are given by NRC in various tables [31, 32]. For additional information, see Nutrient Requirements of Beef Cattle [31] and Nutrient Requirements of Dairy Cattle [32].

## **7. Feeding and nutrition of small ruminants: Sheep and goat**

Nutrition largely affects flock reproduction, milk production and growth in ruminants. Sheep and goat should be fed according to their nutritional needs [33, 34]. Many factors affect their nutrient requirements such as breed, age, body weight, physiological stage and yield level.

The digestive efficiency of sheep, goat and cattle is similar [35]. In general, goat is considered better browsers than sheep, has a higher voluntary feed intake and can digest fibre more efficiently, particularly when fed low or medium-quality diets [36–39].

The digestive processes of neonate lamb and kid having undeveloped pre-stomach (rumen, reticulum and omasum) are very similar to those of monogastric animals. They are unable to digest ordinary carbohydrates except for lactose or grain-based feeds. The first meal of newborn is colostrum providing all nutrients and antibodies. By feeding on dry feeds (good quality roughage and concentrates), rumen becomes inoculated with microorganisms. As the microbes multiply and begin to digest feed, they stimulate the growth and development of the pre-stomach [40]. Lamb/kid's rumen is usually functional at 45–60 days old ages.

After adequate colostrum feeding, lamb/kid may be raised on sheep/goat milk (natural rearing) or milk replacer (artificial rearing). For various reasons such as inadequate milk production, higher milk price, reducing feed costs, and so on, producers may prefer to use artificial rearing. In both rearing system, it is recommended that liquid food feeding continues until lamb/kid weight reaches at least 10 kg. The composition of a good replacer for lamb is as follows: 22–24% crude protein, 25–35% ether extract, less than 1% crude fibre, 5–8% ash and 22–25% lactose [41]. From ~2 weeks of age, they begin to consume solid feeds and should be creep-fed when pasture quality or quantity is limited. Typical feed ingredients of creep ration are ground or cracked corn, alfalfa hay or meal, soybean meal, oat and molasses. The creep ration should have 18–20% crude protein and not be contained urea. *Ad-libitum* or free choice feeding of creep rations can stimulate rumen development and increases the performance of lamb/kids [42].

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[2] EC, No 1831/2003. Regulation (EC) No 1831/2003 of The European Parliament and of The Council of 22 September 2003 on Additives for Use in Animal Nutrition(Text with EEA

[3] Yen J-T. Anatomy of the digestive system and nutritional physiology. In: Lewis AJ, Southern LL, editors. Chapter 3 Swine Nutrition. 2nd ed. CRC Press Taylor and Francis

[4] McGlone J, Pond W. Pig Production: Biological Principles and Applications. Thomson/

[6] Duke GE. Alimentary Canal: Secretion and digestion, special digestive functions, and absorption. In: Sturkie PD, editor. Avian Physiology. 4th ed. New York, NY: Springer-

[7] Leeson S, Summers JD. Scott's Nutrition of the Chicken. Publ. Univ. Books, Guelph,

[8] Nivińska B. Digestion in ruminants. In: ChangC-F, editor. Carbohydrates-Comprehensive Studies on Glycobiology and Glycotechnology. Rijeka, Croatia: InTechOpen; 2012.

[9] Wu G. Principles of Animal Nutrition. CRC Press Taylor & Francis Group; 2018.ISBN:

[10] NRC. Nutrient Requirements of Swine. 11th revised edition. Washington, Washington,

[11] Veum TL, Cheeke PR. Feeding and nutrition of swine. In: Cheeke PR, editor. Applied Animal Nutrition: Feeds and Feeding. 3rd ed. New Jersey, USA: Pearson Prentice Hall;

[12] Cromwell GL. Feeding Levels and Practices in Pigs; 2017. http://www.msdvetmanual. com/management-and-nutrition/nutrition-pigs/feeding-levels-and-practices-in-pigs

[13] Sethiya NK. Review on natural growth promoters available for improving gut health of poultry: An alternative to antibiotic growth promoters. Asian Journal of Poultry Science.

[14] Açıkgöz Z, Yücel B, Altan Ö. The effects of propolis supplementation on broiler perfor-

mance and feed digestibility. ArchivFürGeflügelkunde. 2005;**69**(3):117-122

[5] Chiba LI. Digestive physiology. Animal Nutrition Handbook. 2014;**2**:28-54

Nutrient requirements of sheep**/**goat are just above maintenance during early and mid-gestation occurring placental development. During the last 50 days of gestation, last trimester, nutrient requirements of them substantially increase due to rapid fetal growth, particularly for ewes/goats carrying multiple foetuses. In addition, this is the period when rumen volume decreases and mammary system develops or regenerates. For these reasons, the nutrient density of diet is necessary to increase for assuring adequate nutrition. Especially, energy is important as it affects lamb/kid size and vigour at birth [35].

Milk production of the ewes/goats peaks at 3–4 weeks following lambing/kidding. Ewes/goats with twin and triplet lambs/kids produce more milk than those with singles. They have the greatest nutrient requirements during early lactation period since they should be fed on highquality forages supplemented with concentrates. The concentrate ratio of 50–60% is sufficient. After the first 60 days of lactation, the amount of consumed feed per animal should be reduced to prevent excess fat accumulation and to obtain optimum body condition score (2.5 or 3) [35].

Nutrient requirements of various physiological conditions of sheep and goat have been given by NRC in various tables [33, 34]. For additional information, see Nutrient Requirements of Sheep [33] and Nutrient Requirements of Goat [34].

## **8. Conclusion**

Digestive process of ruminants and non-ruminants varies depending on morphological and functional differences of the digestive tract. These variations clearly affect feed source used their nutrition and the amount and kind of nutrients required by them. Because of differences in their digestive physiology, the availability of individual nutrients can vary from feedstuff to feedstuff. Animals must receive sufficient amounts of all essential nutrients (water, energy, amino acids, vitamins and minerals) to remain healthy, to grow and to produce. Inadequate and unbalanced nutrition causes various feeding disorders or even deaths. For economic animal production, it is important for producers to choose feedstuffs that have nutrients high in bioavailability.

## **Author details**

Figen Kırkpınar\* and Zümrüt Açıkgöz

\*Address all correspondence to: figen.kirkpinar@ege.edu.tr

Department of Animal Sciences, University of Ege, Turkey

## **References**

From ~2 weeks of age, they begin to consume solid feeds and should be creep-fed when pasture quality or quantity is limited. Typical feed ingredients of creep ration are ground or cracked corn, alfalfa hay or meal, soybean meal, oat and molasses. The creep ration should have 18–20% crude protein and not be contained urea. *Ad-libitum* or free choice feeding of creep rations can

Nutrient requirements of sheep**/**goat are just above maintenance during early and mid-gestation occurring placental development. During the last 50 days of gestation, last trimester, nutrient requirements of them substantially increase due to rapid fetal growth, particularly for ewes/goats carrying multiple foetuses. In addition, this is the period when rumen volume decreases and mammary system develops or regenerates. For these reasons, the nutrient density of diet is necessary to increase for assuring adequate nutrition. Especially, energy is

Milk production of the ewes/goats peaks at 3–4 weeks following lambing/kidding. Ewes/goats with twin and triplet lambs/kids produce more milk than those with singles. They have the greatest nutrient requirements during early lactation period since they should be fed on highquality forages supplemented with concentrates. The concentrate ratio of 50–60% is sufficient. After the first 60 days of lactation, the amount of consumed feed per animal should be reduced to prevent excess fat accumulation and to obtain optimum body condition score (2.5 or 3) [35]. Nutrient requirements of various physiological conditions of sheep and goat have been given by NRC in various tables [33, 34]. For additional information, see Nutrient Requirements of

Digestive process of ruminants and non-ruminants varies depending on morphological and functional differences of the digestive tract. These variations clearly affect feed source used their nutrition and the amount and kind of nutrients required by them. Because of differences in their digestive physiology, the availability of individual nutrients can vary from feedstuff to feedstuff. Animals must receive sufficient amounts of all essential nutrients (water, energy, amino acids, vitamins and minerals) to remain healthy, to grow and to produce. Inadequate and unbalanced nutrition causes various feeding disorders or even deaths. For economic animal production, it is important for producers to choose feedstuffs that have nutrients high in

stimulate rumen development and increases the performance of lamb/kids [42].

important as it affects lamb/kid size and vigour at birth [35].

Sheep [33] and Nutrient Requirements of Goat [34].

**8. Conclusion**

110 Animal Husbandry and Nutrition

bioavailability.

**Author details**

Figen Kırkpınar\* and Zümrüt Açıkgöz

\*Address all correspondence to: figen.kirkpinar@ege.edu.tr Department of Animal Sciences, University of Ege, Turkey


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[35] Thompson JM, Cheeke PR. Feeding and nutrition of small ruminants: Sheep, goats and llamas. In: Cheeke PR, editor. Applied Animal Nutrition: Feeds and Feeding. 3rd ed.

[36] García MA, Isac MD, Aguilera JF, Molina-Alcaide E.Rumen fermentation pattern in goats and sheep grazing pastures from semiarid Spanish unsupplemented or supplemented with barley grain or barley grain-urea. Livestock Production Science. 1994;**39**:81-84 [37] Molina-Alcaide E, García MA, Aguilera JF. The voluntary intake and rumen digestion by grazing goats and sheep of a low-quality pasture from a semi-arid land. Livestock

[38] Yáñez-Ruiz DR, Martín-García AI, Moumen A, Molina-Alcaide E. Ruminal fermentation and degradation patterns, protozoa population, and urinary purine derivatives excretion in goats and wethers fed diets based on two-stage olive cake: Effect of PEG supply.

[39] Yáñez-Ruiz DR, Martín-García AI, Moumen A, Molina-Alcaide E. Ruminal fermentation and degradation patterns, protozoa population and urinary purine derivatives excretion in goats and wethers fed diets based on olive leaves. Journal of Animal Science.

[40] Yami A. Nutrition and Feeding of Sheep and Goats. Sheep and Goat Production

[41] Umberger SH. Profitable artificial rearing of lambs. Virginia Cooperative Extension,

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[17] Noy Y, Uni Z.Early nutritional strategies. World's Poultry Science Journal. 2010;**66**:639-646 [18] Shariatmadari F. Plans of feeding broiler chicken. World's Poultry Science Journal. 2012;**68**:

[19] Pottgüter R. Feeding laying hens to 100 weeks of age. Lohmann Information. 2016;

[20] Leeson S, Summers JD. Commercial Poultry Nutrition. 2nd ed. Guelph, Ontario, Canada:

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[22] NRC. Nutrient Requirements of Poultry. 9th revised ed. Washington, DC: National

[25] Hilton M. Nutritional Requirements of Beef Cattle; 2017. http://www.msdvetmanual.com/ management-and-nutrition/nutrition-beef-cattle/nutritional-requirements-of-beef-cattle

[26] Perry TW. Breeding Herd Nutrition and Management. In: Perry TW, Cecava MJ, editors. Beef Cattle Feeding and Nutrition. 2nd ed. A Division of Harcourt Brace & Company 525 B Street, Suite 1900, San Diego, California 92101-4495: Academic Press, Inc; 1995.

[27] Naseri A. Animal Nutrition Training Manual; 2017. http://www.atnesa.org/docs/Alimu-

[28] DelCurto T, Cheeke PR. Feeding and nutrition of beef cattle. In: Cheeke PR, editor. Applied Animal Nutrition: Feeds and Feeding. 3rd ed. New Jersey, USA: Pearson Pren-

[29] Perry TW. Milk production and calf performance. In: Perry TW, Cecava MJ, editors. Beef Cattle Feeding and Nutrition. 2nd ed. A Division of Harcourt Brace & Company 525 B Street, Suite 1900, San Diego, California 92101-4495: Academic Press, Inc; 1995.

[30] Perry TW. Feeding stocker cattle. In: Perry TW, Cecava MJ, editors. Beef Cattle Feeding and Nutrition. Second ed. 525 B Street, Suite 1900, San Diego, California 92101-4495: Academic Press, Inc. A Division of Harcourt Brace & Company; 1995. pp. 242-252

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tice Hall; 2005. pp. 398-419. ISBN: 0-13-113331-4


**Chapter 6**

**Provisional chapter**

**Managing Dietary Energy Intake by Broiler Chickens to**

**Managing Dietary Energy Intake by Broiler Chickens to** 

DOI: 10.5772/intechopen.76972

**Reduce Production Costs and Improve Product Quality**

Feeding constitutes the highest variable cost in poultry production, accounting for at least 60% of such costs, especially in an intensive rearing system. Energy intake is an essential factor in broiler production because of its involvement in growth rate, carcass quality as well as its role in the development of certain metabolic diseases. Dietary energy is supplied in broiler nutrition through different feed resources. Dietary energy content strongly regulates feed consumption, and energy is the most expensive item in poultry diets. At the same time, excess energy intake may result in an increased fat deposition, which affects meat quality and consumer health. This chapter explores the implication of imbalance in energy intake, possible nutritional strategies to restrict energy intake with-

**Keywords:** broiler chickens, energy intake, health, meat quality, nutrition production

One of the objectives of any poultry producer is to feed the chickens with balanced diet at least cost and also generate products that will attract premium prices in order to maximise profit. For many decades, farmers and feed manufacturers have been facing the challenge of effectively reducing the cost of poultry production and produce quality products. Several factors such as genotype, diet composition, digestible nutrient content, energy to protein ratio, feed form, feed processing, environment, and disease could affect the cost of production and

out reducing performance and hence improving meat quality.

**Reduce Production Costs and Improve Product Quality**

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

Emmanuel U. Ahiwe, Apeh A. Omede,

Emmanuel U. Ahiwe, Apeh A. Omede,

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

Medani B. Abdallh and Paul A. Iji

Medani B. Abdallh and Paul A. Iji

http://dx.doi.org/10.5772/intechopen.76972

**Abstract**

cost

**1. Introduction**

**Chapter 6 Provisional chapter**

#### **Managing Dietary Energy Intake by Broiler Chickens to Reduce Production Costs and Improve Product Quality Managing Dietary Energy Intake by Broiler Chickens to Reduce Production Costs and Improve Product Quality**

DOI: 10.5772/intechopen.76972

Emmanuel U. Ahiwe, Apeh A. Omede, Medani B. Abdallh and Paul A. Iji Emmanuel U. Ahiwe, Apeh A. Omede, Medani B. Abdallh and Paul A. Iji

Additional information is available at the end of the chapter Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.76972

#### **Abstract**

Feeding constitutes the highest variable cost in poultry production, accounting for at least 60% of such costs, especially in an intensive rearing system. Energy intake is an essential factor in broiler production because of its involvement in growth rate, carcass quality as well as its role in the development of certain metabolic diseases. Dietary energy is supplied in broiler nutrition through different feed resources. Dietary energy content strongly regulates feed consumption, and energy is the most expensive item in poultry diets. At the same time, excess energy intake may result in an increased fat deposition, which affects meat quality and consumer health. This chapter explores the implication of imbalance in energy intake, possible nutritional strategies to restrict energy intake without reducing performance and hence improving meat quality.

**Keywords:** broiler chickens, energy intake, health, meat quality, nutrition production cost

#### **1. Introduction**

One of the objectives of any poultry producer is to feed the chickens with balanced diet at least cost and also generate products that will attract premium prices in order to maximise profit. For many decades, farmers and feed manufacturers have been facing the challenge of effectively reducing the cost of poultry production and produce quality products. Several factors such as genotype, diet composition, digestible nutrient content, energy to protein ratio, feed form, feed processing, environment, and disease could affect the cost of production and

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

poultry product quality through influencing feed intake, body weight gain and feed conversion ratio (FCR). Dietary management of energy intake has been reported to decrease the cost of production and improve product quality to a greater extent than the abovementioned factors [1]. However, most energy feed ingredients that will help in achieving improved performance, health, reduced production costs and improved product quality in poultry production are continuously becoming scarce and expensive for use in broiler production due to the stiff competition for available energy sources used by industries for biofuel and as food for humans. Feeds that provide the basic nutrients which help to achieve quality broiler carcass yield accounts for over 70% of the overall cost of poultry production, with energy sources being the largest in terms of quantity (40–70%) and invariably the most expensive [2–4].

products has also been inconsistent so far. The variability when dietary energy strategies are applied could be due to various factors such as genotype, diet composition, digestible nutrient content, energy to protein ratio, feed form and feed processing, environment and disease. Suitable mechanisms to keep these sources of variation constant when dietary energy management is applied are worth considering. This chapter seeks to review the shortfall and progress that have been achieved in research into the management of energy content to reduce feed costs, sustain productivity and improve product quality. The nutritive value of energy sources for poultry, recent advances in understanding energy requirements of poultry, cost implications of energy sources, regulation of dietary energy and feed intake in poultry nutrition will also be discussed. The effect/implication of imbalance in energy intake on poultry (growth, fat deposition, potential disease disposition, meat quality), nutritional strategies to restrict energy intake and various implications/benefits of restricted energy intake in poultry

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117

Energy and protein are the second most important feed constituents after water and are needed to maintain health, growth, and production. This explains why energy and protein sources are the most important feed ingredients for poultry feeding. Oilseed cakes and animal protein meals are considered as secondary sources due to their substantial energy content [18]. Cereal grains provide 60–70% of dietary energy for poultry, while other energy and protein sources supply the rest. Although the interaction of protein sources with the main energy sources influences the overall energy supply and utilisation, it is important to determine precisely the energy values of diets containing vegetable sources, whether for least-cost formulation purposes or for adapting feed supply to energy requirements of animals [19]. Some data

Cereals are the grain-producing plants, which can be used as energy sources in animal and human food. These form the largest part of the energy source in poultry diets and consist of the highest inclusion level in a standard poultry diet. Corn, wheat, sorghum, barley, rye, oats, triticale and millet [34–38] represent the main cereal grains used as energy sources in broiler diets. Cereal grains are cultivated in large quantities and provide more starch worldwide in comparison with other types of crops. Recently, grain by-products such as distiller's dried grains with soluble (DDGS) have been used in poultry feeding. Starch constitutes the basis of energy in grains, which is highly digestible especially for poultry. The metabolisable energy content of frequently used grains for poultry ranges from 2734 kcal/kg in rye to 3300 kcal/kg in corn. The nutritional profiles of ground cereal grains vary according to type, location, season, cultivation, harvesting and handling conditions. Although they contain highly digestible starch, most of the grains contain anti-nutrients, which negatively affect the digestion, absorp-

production.

**2. Dietary energy sources for poultry**

**2.1. Cereals grains energy feed ingredients**

tion, and availability of nutrients [39, 40].

on global production of energy sources are shown in **Table 1**.

The continuous increase in the cost of poultry feed ingredients (especially energy sources) has forced some farmers as well as feed manufacturers to use poor quality energy feed ingredients. This practice has resulted to poor feed intake, weight gain, FCR and meat quality [5]. The importance of dietary energy in poultry feeding cannot be over-emphasised because increasing or decreasing the dietary energy has been reported to affect feed intake in addition to promoting or undermining efficient feed utilisation and growth rate [6–9]. Singh and Panda [10] concluded that birds usually eat with the aim of satisfying their energy requirement, and once this aim is achieved, the birds will stop eating irrespective of the fact that other key nutrient requirements such as protein, minerals, and vitamins have not been met. This scenario tends to lead to malnutrition, poor performance, increased deposition of excess abdominal fat or carcass fat in broilers [9, 11], and this fat deposit is usually considered to be waste product when birds are processed. High fat deposition is regarded as an economic loss for poultry producers. Furthermore, energy intake is considered a fundamental factor in broiler production because it not only affects growth rate and carcass characteristics but also causes some metabolic diseases such as ascites and fatty liver syndrome in broiler chickens [12, 13].

Therefore, appropriate focus is usually placed on the inclusion levels of various dietary energy sources when formulating diets for broiler chickens since an increase or decrease of dietary energy could play a key factor in determining not just cost but also the final product quality [7–9]. The nutrient density in the diet should be adjusted to enable appropriate nutrient intake based on requirements and the actual feed intake. Based on these facts, several poultry researchers and nutritionists have over the years directed their research toward finding various strategies aimed at managing dietary energy intake in poultry birds in order to cut down on the cost of production and also improve the quality of poultry products. Results obtained so far have been conflicting, with some authors concluding that dietary energy content could be managed to influence broiler performance and carcass quality [8, 9, 14, 15]. Other authors report that changing the dietary energy content has no effect on broiler performance and carcass quality [16]. Kim et al. [17] reported different responses to energy concentration with different strains of broiler chickens. The management of dietary energy intake in broiler chicken production aimed at reducing production costs and improve the product quality of broiler birds has been practiced for many decades with varying outcomes. Research geared towards achieving both a reduction in the cost of production and improvement of quality broiler products has also been inconsistent so far. The variability when dietary energy strategies are applied could be due to various factors such as genotype, diet composition, digestible nutrient content, energy to protein ratio, feed form and feed processing, environment and disease. Suitable mechanisms to keep these sources of variation constant when dietary energy management is applied are worth considering. This chapter seeks to review the shortfall and progress that have been achieved in research into the management of energy content to reduce feed costs, sustain productivity and improve product quality. The nutritive value of energy sources for poultry, recent advances in understanding energy requirements of poultry, cost implications of energy sources, regulation of dietary energy and feed intake in poultry nutrition will also be discussed. The effect/implication of imbalance in energy intake on poultry (growth, fat deposition, potential disease disposition, meat quality), nutritional strategies to restrict energy intake and various implications/benefits of restricted energy intake in poultry production.

## **2. Dietary energy sources for poultry**

poultry product quality through influencing feed intake, body weight gain and feed conversion ratio (FCR). Dietary management of energy intake has been reported to decrease the cost of production and improve product quality to a greater extent than the abovementioned factors [1]. However, most energy feed ingredients that will help in achieving improved performance, health, reduced production costs and improved product quality in poultry production are continuously becoming scarce and expensive for use in broiler production due to the stiff competition for available energy sources used by industries for biofuel and as food for humans. Feeds that provide the basic nutrients which help to achieve quality broiler carcass yield accounts for over 70% of the overall cost of poultry production, with energy sources being the largest in terms of quantity (40–70%) and invariably the most expensive [2–4].

The continuous increase in the cost of poultry feed ingredients (especially energy sources) has forced some farmers as well as feed manufacturers to use poor quality energy feed ingredients. This practice has resulted to poor feed intake, weight gain, FCR and meat quality [5]. The importance of dietary energy in poultry feeding cannot be over-emphasised because increasing or decreasing the dietary energy has been reported to affect feed intake in addition to promoting or undermining efficient feed utilisation and growth rate [6–9]. Singh and Panda [10] concluded that birds usually eat with the aim of satisfying their energy requirement, and once this aim is achieved, the birds will stop eating irrespective of the fact that other key nutrient requirements such as protein, minerals, and vitamins have not been met. This scenario tends to lead to malnutrition, poor performance, increased deposition of excess abdominal fat or carcass fat in broilers [9, 11], and this fat deposit is usually considered to be waste product when birds are processed. High fat deposition is regarded as an economic loss for poultry producers. Furthermore, energy intake is considered a fundamental factor in broiler production because it not only affects growth rate and carcass characteristics but also causes some metabolic diseases such as ascites and fatty liver syndrome in

Therefore, appropriate focus is usually placed on the inclusion levels of various dietary energy sources when formulating diets for broiler chickens since an increase or decrease of dietary energy could play a key factor in determining not just cost but also the final product quality [7–9]. The nutrient density in the diet should be adjusted to enable appropriate nutrient intake based on requirements and the actual feed intake. Based on these facts, several poultry researchers and nutritionists have over the years directed their research toward finding various strategies aimed at managing dietary energy intake in poultry birds in order to cut down on the cost of production and also improve the quality of poultry products. Results obtained so far have been conflicting, with some authors concluding that dietary energy content could be managed to influence broiler performance and carcass quality [8, 9, 14, 15]. Other authors report that changing the dietary energy content has no effect on broiler performance and carcass quality [16]. Kim et al. [17] reported different responses to energy concentration with different strains of broiler chickens. The management of dietary energy intake in broiler chicken production aimed at reducing production costs and improve the product quality of broiler birds has been practiced for many decades with varying outcomes. Research geared towards achieving both a reduction in the cost of production and improvement of quality broiler

broiler chickens [12, 13].

116 Animal Husbandry and Nutrition

Energy and protein are the second most important feed constituents after water and are needed to maintain health, growth, and production. This explains why energy and protein sources are the most important feed ingredients for poultry feeding. Oilseed cakes and animal protein meals are considered as secondary sources due to their substantial energy content [18]. Cereal grains provide 60–70% of dietary energy for poultry, while other energy and protein sources supply the rest. Although the interaction of protein sources with the main energy sources influences the overall energy supply and utilisation, it is important to determine precisely the energy values of diets containing vegetable sources, whether for least-cost formulation purposes or for adapting feed supply to energy requirements of animals [19]. Some data on global production of energy sources are shown in **Table 1**.

#### **2.1. Cereals grains energy feed ingredients**

Cereals are the grain-producing plants, which can be used as energy sources in animal and human food. These form the largest part of the energy source in poultry diets and consist of the highest inclusion level in a standard poultry diet. Corn, wheat, sorghum, barley, rye, oats, triticale and millet [34–38] represent the main cereal grains used as energy sources in broiler diets. Cereal grains are cultivated in large quantities and provide more starch worldwide in comparison with other types of crops. Recently, grain by-products such as distiller's dried grains with soluble (DDGS) have been used in poultry feeding. Starch constitutes the basis of energy in grains, which is highly digestible especially for poultry. The metabolisable energy content of frequently used grains for poultry ranges from 2734 kcal/kg in rye to 3300 kcal/kg in corn. The nutritional profiles of ground cereal grains vary according to type, location, season, cultivation, harvesting and handling conditions. Although they contain highly digestible starch, most of the grains contain anti-nutrients, which negatively affect the digestion, absorption, and availability of nutrients [39, 40].


consumption. Wheat inclusion in animal feeds depends on seasonal production, price fluctuation during harvesting and the relative market prices of the other energy sources. Wheat is the premier source of energy for poultry diets in Canada, parts of Europe, Australia, and New Zealand [42]. Wheat has high starch content (about 70% DM), providing around 3153 kcal/kg energy for poultry. In addition to its high nutrient digestibility, rolled wheat is very palatable; therefore, it is considered an efficient energy source for all classes of poultry. Wheat has been classified into hard and soft varieties, depending on gluten content. Soft varieties are com-

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Barley is one of the popular cereal grains. It is cultivated in more than 100 countries, almost across all continents. The USA, Canada, Australia, Russia, UK, France, Germany, Ukraine, Spain and Turkey produce around three-quarters of the total world production. This important seasonal plant is ranked fourth after maize, rice and wheat [42]. Barley provides around 2795 kcal/kg energy for poultry, with a low starch content, relatively high fibre content and some ANFs [44]. The lower metabolisable energy (ME) value limits the inclusion of barley in high-energy poultry diet formulation, and it is not included at high rates, particularly in diets

Sorghum is mainly grown in warmer climates, especially in Africa, Asia and Central America. Kafir, Milo, Feterita, Durra and Hegari are the common African and Mediterranean varieties of sorghum, while Sballu, and Kaoliang are Asian types. United States varieties were originally produced from crossing Kafir and Milo. In addition, sorghum is classified according to the tannin content to high- and low-tannin types. Tannins are ANFs, which reduce the availability of protein during digestion [46]. The content of tannin in sorghum limits its use in poultry diets, although tannin-free varieties are available now but in inadequate amounts. Sorghum is considered the major source of energy for poultry feeds in some Asian and most African countries, due to its high energy content (3263 kcal/kg). Using rolled sorghum is a common practice in poultry feed formulation, although sometimes whole grain feeding is

Rye is originally a south-west Asian plant, but now it is growing in all Asia, Europe, Africa and North America (especially Canada). Rye contains high starch content (around 62%), with an energy content of about 2734 kcal/kg energy for poultry and has a low fibre content. Despite the rich nutrient profile, rye is not competitive as a source of energy for poultry because of the presence of ergotism, resorcinols and large amounts of soluble arabinoxylans, which decrease the nutrient bioavailability for birds, leading to a depression in growth and productivity. On the other hand, this composition makes it a good source of low-fibre energy

diets. Rye is considered less palatable than other cereal grains [48].

monly used as main ingredients in poultry feeds [43].

*2.1.3. Barley*

for young birds [45].

well known in rural areas [47].

*2.1.4. Sorghum*

*2.1.5. Rye*

**Table 1.** Global production and major producers of different energy feed sources (2017).

#### *2.1.1. Corn*

Corn, also called maize, was first grown in America by the American-Indians. According to the physical appearance of the kernel, there are seven types of corn worldwide, including flint, flour, dent, pop, sweet, waxy and pod. Nowadays, most of the grown corn is the hybrid, produced by crossing inbred lines through several generations. As a plant, corn is efficient at converting great amounts of sunlight into constant forms of energy and stored as starch, cellulose, and oil. The corn bushel approximately consists of 65.6% starch, 26% gluten feed, 5.2% gluten meal and 3.2% corn oil. Corn is the principal cereal grain for poultry feeds around the world, especially in the United States [41]. Due to its good energy content (3300 kcal/kg of energy for poultry), high starch digestibility and low fibre, it is extremely palatable and almost free from anti-nutritional factors (ANF). Corn is considered as the standard by which alternative grains are evaluated.

#### *2.1.2. Wheat*

China, India, the USA, the Russian Federation, France, Pakistan, Germany, Canada, and Turkey represent the main wheat producing countries. Generally, wheat is grown for human consumption. Wheat inclusion in animal feeds depends on seasonal production, price fluctuation during harvesting and the relative market prices of the other energy sources. Wheat is the premier source of energy for poultry diets in Canada, parts of Europe, Australia, and New Zealand [42]. Wheat has high starch content (about 70% DM), providing around 3153 kcal/kg energy for poultry. In addition to its high nutrient digestibility, rolled wheat is very palatable; therefore, it is considered an efficient energy source for all classes of poultry. Wheat has been classified into hard and soft varieties, depending on gluten content. Soft varieties are commonly used as main ingredients in poultry feeds [43].

#### *2.1.3. Barley*

Barley is one of the popular cereal grains. It is cultivated in more than 100 countries, almost across all continents. The USA, Canada, Australia, Russia, UK, France, Germany, Ukraine, Spain and Turkey produce around three-quarters of the total world production. This important seasonal plant is ranked fourth after maize, rice and wheat [42]. Barley provides around 2795 kcal/kg energy for poultry, with a low starch content, relatively high fibre content and some ANFs [44]. The lower metabolisable energy (ME) value limits the inclusion of barley in high-energy poultry diet formulation, and it is not included at high rates, particularly in diets for young birds [45].

#### *2.1.4. Sorghum*

Sorghum is mainly grown in warmer climates, especially in Africa, Asia and Central America. Kafir, Milo, Feterita, Durra and Hegari are the common African and Mediterranean varieties of sorghum, while Sballu, and Kaoliang are Asian types. United States varieties were originally produced from crossing Kafir and Milo. In addition, sorghum is classified according to the tannin content to high- and low-tannin types. Tannins are ANFs, which reduce the availability of protein during digestion [46]. The content of tannin in sorghum limits its use in poultry diets, although tannin-free varieties are available now but in inadequate amounts. Sorghum is considered the major source of energy for poultry feeds in some Asian and most African countries, due to its high energy content (3263 kcal/kg). Using rolled sorghum is a common practice in poultry feed formulation, although sometimes whole grain feeding is well known in rural areas [47].

#### *2.1.5. Rye*

*2.1.1. Corn*

*Root and tuber energy sources*

*Plant protein energy sources*

*Cereal grains*

118 Animal Husbandry and Nutrition

**Ingredient Global production** 

**(m tonnes)**

Corn 1031.6 USA, China, Brazil, European Union,

Oat 23.3 European Union, Russia, Canada, Poland,

Rye 12.6 European Union, Russia, Belarus, Ukraine,

Cassava 27.0 Nigeria, Thailand, Indonesia, Brazil,

Sunflower meal 45.6 Ukraine, Russia, European Union,

**Table 1.** Global production and major producers of different energy feed sources (2017).

Triticale 5.2 Poland, Germany, Belarus, France, Russia. [25] Millet 29.9 India, Nigeria, Niger, China, Mali. [26]

Potato 393.75 China, India, Russia, Ukraine, USA. [28]

Soybean meal 345.9 USA, Brazil, Argentina, China, India [29, 30]

Cotton seed meal 13.9 India, China, Pakistan, Brazil, USA. [32, 33]

Argentina.

Ukraine.

Finland

Turkey.

Vietnam

Argentina, Turkey.

Wheat 2627 China, India, Russia, USA, France. [21, 22] Sorghum 59.34 USA, Nigeria, Mexico, India, Sudan [23] Barley 137.47 European Union, Russia, Australia, Canada,

*2.1.2. Wheat*

Corn, also called maize, was first grown in America by the American-Indians. According to the physical appearance of the kernel, there are seven types of corn worldwide, including flint, flour, dent, pop, sweet, waxy and pod. Nowadays, most of the grown corn is the hybrid, produced by crossing inbred lines through several generations. As a plant, corn is efficient at converting great amounts of sunlight into constant forms of energy and stored as starch, cellulose, and oil. The corn bushel approximately consists of 65.6% starch, 26% gluten feed, 5.2% gluten meal and 3.2% corn oil. Corn is the principal cereal grain for poultry feeds around the world, especially in the United States [41]. Due to its good energy content (3300 kcal/kg of energy for poultry), high starch digestibility and low fibre, it is extremely palatable and almost free from anti-nutritional factors (ANF). Corn is considered as the standard by which alternative grains are evaluated.

**Top producers References**

[20]

[24]

[24]

[24]

[27]

[31]

China, India, the USA, the Russian Federation, France, Pakistan, Germany, Canada, and Turkey represent the main wheat producing countries. Generally, wheat is grown for human Rye is originally a south-west Asian plant, but now it is growing in all Asia, Europe, Africa and North America (especially Canada). Rye contains high starch content (around 62%), with an energy content of about 2734 kcal/kg energy for poultry and has a low fibre content. Despite the rich nutrient profile, rye is not competitive as a source of energy for poultry because of the presence of ergotism, resorcinols and large amounts of soluble arabinoxylans, which decrease the nutrient bioavailability for birds, leading to a depression in growth and productivity. On the other hand, this composition makes it a good source of low-fibre energy diets. Rye is considered less palatable than other cereal grains [48].

#### *2.1.6. Oats*

Oats are one of the cool and high moisture area plants, also they can grow at high altitude of tropical areas. Russia and Canada are considered the main producers of oats followed by Poland and Australia, respectively. Undehulled oats are low in starch (around 40%), offering about 2756 kcal/kg energy for poultry, while the dehulled oats contain around 60% starch. The presence of ANF such as β-glucans and high fibre contents are the common constraints to the use of oats in poultry diets. In addition, the high oil content of oats can lead to development of off flavour in chicken meat. Inclusion of oats in low amounts is suitable for pullets and breeders [49].

**2.4. Energy from protein sources**

*2.4.1. Plant protein sources*

protein sources.

*2.4.2. Animal protein sources*

for poultry, respectively [60].

**3. Nutritive value of energy sources in poultry**

While cereal grains provide 60–70% of dietary energy for poultry, protein sources also supply a considerable amount of energy. There are plant and animal protein sources. On their own, proteins are denser in energy than carbohydrates although they are not used as energy

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Although the energy value of various plant protein sources is not as high as the cereal or root and tuber energy ingredient source, they have a considerable amount of energy that helps in furnishing the required energy needed for optimum poultry performance and cost reduction. Examples include soybean meal, canola meal, cottonseed meal, sunflower meal, peas and lupin [36–38]. Geographical location of production, the season of production, method of cultivation, genetic and environmental impacts, as well as processing method and the amount of remaining oil are the main causes of differences in energy content between different vegetable

Although they are major sources of protein, they also contain considerable amounts of energy. Examples include meat meal, fish meal, blood meal, feather meal and poultry by-product [36–38]. The differences in the energy content of animal protein sources may be attributed to animal species, part of the body, and processing methods. Soybean, canola, cottonseed and sunflower seed contain an average of 2557, 2000, 2350, 2205 kcal/kg ME for poultry, while meat and bone, meat, fish, poultry by-product contain around 2475, 2500, 2720, 2950 kcal/kg

Feed formulation involves a prudent usage of various (available) feed ingredients to supply sufficient amount and proportions of several nutrients required by poultry. Poultry feed is made up of many ingredients, and these ingredients are grouped into those that provide energy (fats, oils, and carbohydrates), protein (amino acids), vitamins, and minerals. Among the feed nutrients, dietary energy is one of the most important because it influences the utilisation of other nutrients through its ability to regulate feed intake to a high degree. Formulating poultry diets should be done with the aim of achieving optimum energy level based on the composition of the feed ingredient to lower feed cost per unit of poultry product and produce quality end-products. In animal feeds, energy supply represents a major part of the cost of the formula. Since feed ingredients that supply energy in a standard broiler diet are in the highest amount (40–70%) in terms of inclusion level [2–4, 61], it is important to improve the knowledge of energy utilisation and energy requirement by the animal to better meet its energy needs. Therefore, having systems in place to evaluate the energy content of raw materials

sources due to cost and physiological burden of excreting them from the body.

#### *2.1.7. Triticale*

Triticale is the result of crossbreeding between wheat (mainly durum type) and rye, so it is a hybrid grain produced in German and Scottish laboratories in the nineteenth century. This crossing process introduced a new cereal grain species with wide adaptability, environmental tolerance, and improved nutritional value, to be grown in areas not proper for maize, rye and wheat around the world [50]. The currently developed varieties of triticale contain on average, 110 kcal/kg energy for poultry, with low fibre content; therefore, it has been included at rates up to 30% in broiler diets, and at slightly lower levels in layers diets. Furthermore, unlike the other cereal grains, different varieties of triticale almost similar in their energy content, which maintains consistent poultry performance [51].

#### **2.2. Root and tubers**

Starchy root and tuber crops are second only in importance to cereals [52]. Most of these roots and tubers are high in metabolisable energy, but their usage as poultry feed ingredients is limited because of the presence of anti-nutritional factors. However, these anti-nutrients are reduced or eliminated through adequate processing methods. Examples of these crops include cassava, cocoyam and potato [53–56].

#### **2.3. Fats and oils**

Fats and oils are collectively known as lipids. They provide significant amounts of energy to poultry diets, but there is a large variation in composition, quality, feeding value, and price. These notwithstanding, they are regularly used in poultry feeds to satisfy the energy need of the animal as lipids have more than twice the amount of ME than carbohydrates or proteins per kg weight. However, they are normally included at a maximum level of 4–5%. The commonly used types of fat in poultry diets include tallow, poultry fat, feed-grade animal fat and yellow grease. Animal fats provide an average ME of 8850 kcal/kg for poultry. Similarly, oils have a high content of energy, the average ME content of different types of vegetable oils ranging between 8300 and 8975 kcal/kg. The commonly used oils in broiler diets are soybean oil, canola oil, and palm oil. Besides the concentrated energy, including fats and oils in poultry diets improves the physical traits and palatability of diet, increases pellet durability and enhances the essential fatty acid contents of the diets, especially linoleic acid [57–59].

#### **2.4. Energy from protein sources**

While cereal grains provide 60–70% of dietary energy for poultry, protein sources also supply a considerable amount of energy. There are plant and animal protein sources. On their own, proteins are denser in energy than carbohydrates although they are not used as energy sources due to cost and physiological burden of excreting them from the body.

#### *2.4.1. Plant protein sources*

*2.1.6. Oats*

120 Animal Husbandry and Nutrition

and breeders [49].

**2.2. Root and tubers**

**2.3. Fats and oils**

*2.1.7. Triticale*

Oats are one of the cool and high moisture area plants, also they can grow at high altitude of tropical areas. Russia and Canada are considered the main producers of oats followed by Poland and Australia, respectively. Undehulled oats are low in starch (around 40%), offering about 2756 kcal/kg energy for poultry, while the dehulled oats contain around 60% starch. The presence of ANF such as β-glucans and high fibre contents are the common constraints to the use of oats in poultry diets. In addition, the high oil content of oats can lead to development of off flavour in chicken meat. Inclusion of oats in low amounts is suitable for pullets

Triticale is the result of crossbreeding between wheat (mainly durum type) and rye, so it is a hybrid grain produced in German and Scottish laboratories in the nineteenth century. This crossing process introduced a new cereal grain species with wide adaptability, environmental tolerance, and improved nutritional value, to be grown in areas not proper for maize, rye and wheat around the world [50]. The currently developed varieties of triticale contain on average, 110 kcal/kg energy for poultry, with low fibre content; therefore, it has been included at rates up to 30% in broiler diets, and at slightly lower levels in layers diets. Furthermore, unlike the other cereal grains, different varieties of triticale almost similar in their energy content,

Starchy root and tuber crops are second only in importance to cereals [52]. Most of these roots and tubers are high in metabolisable energy, but their usage as poultry feed ingredients is limited because of the presence of anti-nutritional factors. However, these anti-nutrients are reduced or eliminated through adequate processing methods. Examples of these crops

Fats and oils are collectively known as lipids. They provide significant amounts of energy to poultry diets, but there is a large variation in composition, quality, feeding value, and price. These notwithstanding, they are regularly used in poultry feeds to satisfy the energy need of the animal as lipids have more than twice the amount of ME than carbohydrates or proteins per kg weight. However, they are normally included at a maximum level of 4–5%. The commonly used types of fat in poultry diets include tallow, poultry fat, feed-grade animal fat and yellow grease. Animal fats provide an average ME of 8850 kcal/kg for poultry. Similarly, oils have a high content of energy, the average ME content of different types of vegetable oils ranging between 8300 and 8975 kcal/kg. The commonly used oils in broiler diets are soybean oil, canola oil, and palm oil. Besides the concentrated energy, including fats and oils in poultry diets improves the physical traits and palatability of diet, increases pellet durability and

enhances the essential fatty acid contents of the diets, especially linoleic acid [57–59].

which maintains consistent poultry performance [51].

include cassava, cocoyam and potato [53–56].

Although the energy value of various plant protein sources is not as high as the cereal or root and tuber energy ingredient source, they have a considerable amount of energy that helps in furnishing the required energy needed for optimum poultry performance and cost reduction. Examples include soybean meal, canola meal, cottonseed meal, sunflower meal, peas and lupin [36–38]. Geographical location of production, the season of production, method of cultivation, genetic and environmental impacts, as well as processing method and the amount of remaining oil are the main causes of differences in energy content between different vegetable protein sources.

#### *2.4.2. Animal protein sources*

Although they are major sources of protein, they also contain considerable amounts of energy. Examples include meat meal, fish meal, blood meal, feather meal and poultry by-product [36–38]. The differences in the energy content of animal protein sources may be attributed to animal species, part of the body, and processing methods. Soybean, canola, cottonseed and sunflower seed contain an average of 2557, 2000, 2350, 2205 kcal/kg ME for poultry, while meat and bone, meat, fish, poultry by-product contain around 2475, 2500, 2720, 2950 kcal/kg for poultry, respectively [60].

## **3. Nutritive value of energy sources in poultry**

Feed formulation involves a prudent usage of various (available) feed ingredients to supply sufficient amount and proportions of several nutrients required by poultry. Poultry feed is made up of many ingredients, and these ingredients are grouped into those that provide energy (fats, oils, and carbohydrates), protein (amino acids), vitamins, and minerals. Among the feed nutrients, dietary energy is one of the most important because it influences the utilisation of other nutrients through its ability to regulate feed intake to a high degree. Formulating poultry diets should be done with the aim of achieving optimum energy level based on the composition of the feed ingredient to lower feed cost per unit of poultry product and produce quality end-products. In animal feeds, energy supply represents a major part of the cost of the formula. Since feed ingredients that supply energy in a standard broiler diet are in the highest amount (40–70%) in terms of inclusion level [2–4, 61], it is important to improve the knowledge of energy utilisation and energy requirement by the animal to better meet its energy needs. Therefore, having systems in place to evaluate the energy content of raw materials


and feeds is a determining factor in least-cost formulation. The energy requirement for broilers at different phases of growth and breeds are 3000 kcal ME/kg or 12.55 MJ/kg (starter); 3100 kcal ME/kg or 12.97 MJ/kg (growers) and 3200 kcal ME/kg or 13.39 MJ/kg (finisher) [62]. Since management of dietary energy could influence cost and product quality based on the inclusion levels of various feed ingredients, a summarised table showing various feed ingredients that supply high to moderate energy to show farmers and feed manufacturers that are interested in manipulating cost and achieving improved broiler products through the use of dietary energy will not only give the targeted audience a sense of direction but also save cost. The nutrient composition of various energy feedstuffs is shown in **Table 2**. Each energy source has a different composition due to factors such as regional location, manufacturing

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Adequate knowledge of broiler nutritional requirements based on breed, the energy composition of a feed ingredient, availability and cost of these ingredients is fundamental in least cost formulation and achieving improved broiler performance. Manipulating dietary energy has been reported to influence feed intake with a resultant effect on performance and carcass quality. Poultry adjust their feed intake to accommodate a wide range of diets with differing energy contents at different ages and in response to various factors, including dietary energy [69]. Therefore, appropriately analysed information on different dietary energy contents of several energy-rich feedstuffs becomes important. However, the high cost of feed analysis makes it always difficult for farmers (especially for small-scale farmers) and feed manufacturers to analyse each batch of feedstuff for its nutrient content. Invariably, they usually rely on feedstuff composition data that have been compiled based on many laboratory analyses. Therefore, it becomes imperative to present a reasonable, accurate and summarised estimate of energy contents of feed ingredient for farmers, researchers and feed manufacturers, to enable them to cut down on cost and time that would have been taken to analyse and obtain more accurate laboratory data. The energy which a bird uses for maintenance and productive functions is obtained mainly from starches (carbohydrates), lipids and protein. Energy feed ingredients could be classified into cereal grains, root and tubers, plant protein sources, animal protein sources, fats and oil, as discussed in Section 2 of this chapter. These feed ingredients provide high to moderate dietary energy. Therefore, adequate knowledge and skills are required in using these ingredients to get the best possible least-cost formulation and achieve improved product quality.

The poultry industry relies on a limited number of energy sources, mainly cereal grains and their by-products, in addition to oils and fats, which are normally included in small proportions in poultry diets [70]. Utilising the low-cost locally available energy sources to feed poultry is a nutritionally and economically proven way to reduce the cost and product inefficiency. Annual production, availability, cost of production, prices of other sources, productivity variations and the stiff competition with humans are the main factors affecting the prices of vital cereal grains needed for poultry feeding. Scientifically, assessing cost of feed ingredients depends on its quality evaluation, which is very important to specify ingredient suitability to meet the nutrient specification of poultry to such production type. The ingredient

practices and climatic conditions [37].

**4. Cost implications of energy sources**

**Table 2.** Metabolisable energy values of different energy sources for poultry nutrition.

and feeds is a determining factor in least-cost formulation. The energy requirement for broilers at different phases of growth and breeds are 3000 kcal ME/kg or 12.55 MJ/kg (starter); 3100 kcal ME/kg or 12.97 MJ/kg (growers) and 3200 kcal ME/kg or 13.39 MJ/kg (finisher) [62]. Since management of dietary energy could influence cost and product quality based on the inclusion levels of various feed ingredients, a summarised table showing various feed ingredients that supply high to moderate energy to show farmers and feed manufacturers that are interested in manipulating cost and achieving improved broiler products through the use of dietary energy will not only give the targeted audience a sense of direction but also save cost. The nutrient composition of various energy feedstuffs is shown in **Table 2**. Each energy source has a different composition due to factors such as regional location, manufacturing practices and climatic conditions [37].

Adequate knowledge of broiler nutritional requirements based on breed, the energy composition of a feed ingredient, availability and cost of these ingredients is fundamental in least cost formulation and achieving improved broiler performance. Manipulating dietary energy has been reported to influence feed intake with a resultant effect on performance and carcass quality. Poultry adjust their feed intake to accommodate a wide range of diets with differing energy contents at different ages and in response to various factors, including dietary energy [69]. Therefore, appropriately analysed information on different dietary energy contents of several energy-rich feedstuffs becomes important. However, the high cost of feed analysis makes it always difficult for farmers (especially for small-scale farmers) and feed manufacturers to analyse each batch of feedstuff for its nutrient content. Invariably, they usually rely on feedstuff composition data that have been compiled based on many laboratory analyses. Therefore, it becomes imperative to present a reasonable, accurate and summarised estimate of energy contents of feed ingredient for farmers, researchers and feed manufacturers, to enable them to cut down on cost and time that would have been taken to analyse and obtain more accurate laboratory data. The energy which a bird uses for maintenance and productive functions is obtained mainly from starches (carbohydrates), lipids and protein. Energy feed ingredients could be classified into cereal grains, root and tubers, plant protein sources, animal protein sources, fats and oil, as discussed in Section 2 of this chapter. These feed ingredients provide high to moderate dietary energy. Therefore, adequate knowledge and skills are required in using these ingredients to get the best possible least-cost formulation and achieve improved product quality.

## **4. Cost implications of energy sources**

**Ingredients Metabolisable energy (kcal/kg) References**

Corn 3300–3319 [34–38] Wheat 3153–3430 [34, 37, 38] Sorghum 3263–3550 [34–38] Barley 2734–2760 [36–38] Oat grain 2550–2756 [36–38] Rye 2710–2734 [36, 38] Triticale 3110–3150 [36–38] Millet 3240 [36, 37]

Cassava 3000–3279 [63, 64] Cocoyam 3476 [55, 56] Potato 2370–3190 [25, 26]

Soybean meal 2557 [36, 38] Canola meal 2000–2186 [36–38, 65] Sunflower meal 2205–2310 [36–38] Cotton seed meal 2350–2640 [36–38] Peas 2550 [38] Lupine 3000 [36, 38]

Meat meal 2500–2685 [37, 38] Blood meal 2690–3220 [36–38] Fish meal 2600–2970 [37, 38] Feather meal 2880–3016 [37, 38] Poultry by products 2950 [38]

Animal tallow 6020–7780 [57, 59] Lard 7200–9854 [57, 59, 66–68] Soybean oil 8800–9659 [57, 59] Canola oil 9000–9260 [57, 59] Cotton seed oil 8160–8630 [57, 59] Palm oil 5302–7810 [57, 59] Fish oil 8270–8690 [57, 59] Poultry fat 8020–10,212 [57, 59] Molasses 900–1080 [36, 37]

**Table 2.** Metabolisable energy values of different energy sources for poultry nutrition.

*Cereal grains*

122 Animal Husbandry and Nutrition

*Roots and tubers*

*Plant proteins*

*Animal proteins*

*Fats and oils*

The poultry industry relies on a limited number of energy sources, mainly cereal grains and their by-products, in addition to oils and fats, which are normally included in small proportions in poultry diets [70]. Utilising the low-cost locally available energy sources to feed poultry is a nutritionally and economically proven way to reduce the cost and product inefficiency. Annual production, availability, cost of production, prices of other sources, productivity variations and the stiff competition with humans are the main factors affecting the prices of vital cereal grains needed for poultry feeding. Scientifically, assessing cost of feed ingredients depends on its quality evaluation, which is very important to specify ingredient suitability to meet the nutrient specification of poultry to such production type. The ingredient dry matter content and metabolisable energy concentration are crucial keys to evaluate the cereal grain quality and enable real calculation of energy cost for each source. In addition, poultry performance is highly correlated to energy intake, therefore the best energy source is that which supports the best products to maximise the returns [71].

infers that feed characteristics have had to be continuously changed by feed manufacturers [76], to possibly meet the demand imposed by this development. The performance of poultry in terms of feed conversion ratio is largely dependent on ME values of feed ingredients. While Pym [77] and Fairfull and Chambers [78] once postulated that the effect of genetic selection on ME is relatively insignificant, this theory requires a second look at recent studies indicate otherwise, with growing birds fed wheat-based diets showing high heritability of ME values [79]. The assumption is that birds selected for fast growth rate should require a higher energy. However, one possibility may be that broiler genetic improvement results in the consequent loss of sensitivity to control feed intake based on dietary energy level. Richards [80] reported that feed intake is not properly regulated voluntarily in broilers selected both for faster body weight gain and deposition of muscle according to energy level, as in an *ad libitum* program where compulsive appetite and excessive fat accumulation was observed. Hence, the energy concentration of diets used for broiler selection has remained unchanged over time, suggesting that selection has accustomed broilers to a diluted diet compared to the concentration required to support their growth rate [76]. Hence, determining the energy requirements of poultry with the recent improvement may require species-specific as well as selection infor-

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**6. Regulation of dietary energy and feed intake in poultry nutrition**

The amount of feed consumed by an animal determines the amount of nutrient that is available to the animal for maintenance and production functions [81]. Feed intake tends to influence body weight gain, FCR, cost and carcass quality. Based on these facts, adequate regulation of feed intake using several strategies becomes a critical action aimed towards achieving quality product and controls the cost of poultry production. Factors such as dietary factors (dietary nutrient composition, feed formulation, feedstuff inclusion levels and pellet quality) and managerial factors (feed and water availability to the birds, environmental management, stocking density and disease regulation) individually or collectively influence feed intake in poultry production [1, 81]. Among the abovementioned factors, dietary factors (dietary nutrient composition) have been reported to have a great/significant effect, with dietary energy intake having the most predictable effect on feed intake when applied on poultry [1, 82]. Feed intake has been reported to increase or decrease as dietary energy intake decreases or increases, respectively [69]. This increase or decrease in feed intake in relationship to dietary energy content is influenced by the amount of feed in the gut or other physiological limitations. Dietary energy intake has been reported to also influence growth rate and carcass quality through its effect on feed intake [83]. The ability to sense energy status and adjust metabolic pathway activity in response is a basic function of cells in all animal species [84]. Energy-sensing pathways are present in the central nervous system (CNS) and peripheral tissues of birds, and they represent another set of regulatory mechanisms that are used to modulate peripheral tissue metabolic activity as well as regulate feed intake, energy expenditure to maintain energy balance and body weight [85]. To regulate feed intake, dietary energy intake must be balanced with energy expenditure in the birds. This is monitored/controlled by the hypothalamus [86]. The hypothalamus in the brain of poultry plays an essential role in interpreting

mation to obtain optimal energy requirement for birds.

Feed manufacturers target the available energy sources with reasonable price to use, so availability, price, competition, and quality represent the main handicaps that facing processors to produce cost-efficient and high quality feeds. Globally, corn is the premier energy source, but the high demand for it by humans and animals affects its price and availability. Therefore, to solve this problem, in the most consuming countries such as US, Brazil, and some Asian countries they have started to use a major co-product – distillers' dried grains with soluble (DDGS), because of its cost-effectiveness, good nutrient profile and ready availability. Wheat has been used to replace corn in some parts of the USA, China and India due to the price difference. The expansion in poultry production in the developing countries is forcing the producers to import feed ingredients, increasing the pressure on the prices and quality of feeds. In Australia, because of the low price of sorghum it has been used instead of expensive wheat in summer, while barley and rye are used in some European countries when their prices are lower [72, 73].

The principal goals of manipulations in use of energy sources are to adjust ingredient costs, to reduce the cost of production and maintain the sustainability of the poultry industry. This can be achieved by meeting the nutrient requirements of birds and producing low-cost meat and eggs to satisfy the consumer desire. The rate of inclusion of cereal grains in poultry diets mainly depends on their current costs and nutritive values, therefore changing and replacing energy sources should not be in huge and sudden, to prevent digestive upsets and feed intake depression, which will reduce birds' productivity and production efficiency. Likewise, the price of energy sources has an impact on the cost of poultry feed and a corresponding increase in the total cost of poultry production and the cost of poultry products. This dilemma has affected the profitability of poultry production globally, reducing the interest of existing and potential poultry farmers in the business. Furthermore, this situation, coupled with the increasing demand for animal protein by humans, has caused great concern globally [74].

## **5. Recent advances in understanding energy requirements of poultry**

Meremikwu [75] reported that one of the technical constraints to successful poultry production in the tropics is strict adherence to nutritional standards. According to Meremikwu [75], nutritional standards such as NRC [57] may over-specify diets in many low-income, resourcepoor countries (particularly those in the humid tropics) because of environmental constraints. For decades, the widely accepted theory was that birds eat to constant energy intake, irrespective of the energy level of the feed. However, with advances in genetic selection over the years, this understanding has shifted drastically. The continuous improvement of poultry birds, especially broiler chickens through genetic selection, initially developed by focusing on growth and laying rate, then, by taking other physiological aspects into account has reinforced the poultry bird's potential for better feed efficiency. From a nutritional perspective, such genetic selection has led to changes in nutrient requirements of improved birds, which infers that feed characteristics have had to be continuously changed by feed manufacturers [76], to possibly meet the demand imposed by this development. The performance of poultry in terms of feed conversion ratio is largely dependent on ME values of feed ingredients. While Pym [77] and Fairfull and Chambers [78] once postulated that the effect of genetic selection on ME is relatively insignificant, this theory requires a second look at recent studies indicate otherwise, with growing birds fed wheat-based diets showing high heritability of ME values [79]. The assumption is that birds selected for fast growth rate should require a higher energy. However, one possibility may be that broiler genetic improvement results in the consequent loss of sensitivity to control feed intake based on dietary energy level. Richards [80] reported that feed intake is not properly regulated voluntarily in broilers selected both for faster body weight gain and deposition of muscle according to energy level, as in an *ad libitum* program where compulsive appetite and excessive fat accumulation was observed. Hence, the energy concentration of diets used for broiler selection has remained unchanged over time, suggesting that selection has accustomed broilers to a diluted diet compared to the concentration required to support their growth rate [76]. Hence, determining the energy requirements of poultry with the recent improvement may require species-specific as well as selection information to obtain optimal energy requirement for birds.

dry matter content and metabolisable energy concentration are crucial keys to evaluate the cereal grain quality and enable real calculation of energy cost for each source. In addition, poultry performance is highly correlated to energy intake, therefore the best energy source is

Feed manufacturers target the available energy sources with reasonable price to use, so availability, price, competition, and quality represent the main handicaps that facing processors to produce cost-efficient and high quality feeds. Globally, corn is the premier energy source, but the high demand for it by humans and animals affects its price and availability. Therefore, to solve this problem, in the most consuming countries such as US, Brazil, and some Asian countries they have started to use a major co-product – distillers' dried grains with soluble (DDGS), because of its cost-effectiveness, good nutrient profile and ready availability. Wheat has been used to replace corn in some parts of the USA, China and India due to the price difference. The expansion in poultry production in the developing countries is forcing the producers to import feed ingredients, increasing the pressure on the prices and quality of feeds. In Australia, because of the low price of sorghum it has been used instead of expensive wheat in summer, while barley and rye are used in some European countries when their prices are lower [72, 73]. The principal goals of manipulations in use of energy sources are to adjust ingredient costs, to reduce the cost of production and maintain the sustainability of the poultry industry. This can be achieved by meeting the nutrient requirements of birds and producing low-cost meat and eggs to satisfy the consumer desire. The rate of inclusion of cereal grains in poultry diets mainly depends on their current costs and nutritive values, therefore changing and replacing energy sources should not be in huge and sudden, to prevent digestive upsets and feed intake depression, which will reduce birds' productivity and production efficiency. Likewise, the price of energy sources has an impact on the cost of poultry feed and a corresponding increase in the total cost of poultry production and the cost of poultry products. This dilemma has affected the profitability of poultry production globally, reducing the interest of existing and potential poultry farmers in the business. Furthermore, this situation, coupled with the increasing demand for animal protein by humans, has caused great concern globally [74].

**5. Recent advances in understanding energy requirements of poultry**

Meremikwu [75] reported that one of the technical constraints to successful poultry production in the tropics is strict adherence to nutritional standards. According to Meremikwu [75], nutritional standards such as NRC [57] may over-specify diets in many low-income, resourcepoor countries (particularly those in the humid tropics) because of environmental constraints. For decades, the widely accepted theory was that birds eat to constant energy intake, irrespective of the energy level of the feed. However, with advances in genetic selection over the years, this understanding has shifted drastically. The continuous improvement of poultry birds, especially broiler chickens through genetic selection, initially developed by focusing on growth and laying rate, then, by taking other physiological aspects into account has reinforced the poultry bird's potential for better feed efficiency. From a nutritional perspective, such genetic selection has led to changes in nutrient requirements of improved birds, which

that which supports the best products to maximise the returns [71].

124 Animal Husbandry and Nutrition

## **6. Regulation of dietary energy and feed intake in poultry nutrition**

The amount of feed consumed by an animal determines the amount of nutrient that is available to the animal for maintenance and production functions [81]. Feed intake tends to influence body weight gain, FCR, cost and carcass quality. Based on these facts, adequate regulation of feed intake using several strategies becomes a critical action aimed towards achieving quality product and controls the cost of poultry production. Factors such as dietary factors (dietary nutrient composition, feed formulation, feedstuff inclusion levels and pellet quality) and managerial factors (feed and water availability to the birds, environmental management, stocking density and disease regulation) individually or collectively influence feed intake in poultry production [1, 81]. Among the abovementioned factors, dietary factors (dietary nutrient composition) have been reported to have a great/significant effect, with dietary energy intake having the most predictable effect on feed intake when applied on poultry [1, 82]. Feed intake has been reported to increase or decrease as dietary energy intake decreases or increases, respectively [69]. This increase or decrease in feed intake in relationship to dietary energy content is influenced by the amount of feed in the gut or other physiological limitations. Dietary energy intake has been reported to also influence growth rate and carcass quality through its effect on feed intake [83]. The ability to sense energy status and adjust metabolic pathway activity in response is a basic function of cells in all animal species [84]. Energy-sensing pathways are present in the central nervous system (CNS) and peripheral tissues of birds, and they represent another set of regulatory mechanisms that are used to modulate peripheral tissue metabolic activity as well as regulate feed intake, energy expenditure to maintain energy balance and body weight [85]. To regulate feed intake, dietary energy intake must be balanced with energy expenditure in the birds. This is monitored/controlled by the hypothalamus [86]. The hypothalamus in the brain of poultry plays an essential role in interpreting all information and generating the appropriate responses in feed intake and energy requirement needed to maintain energy homeostasis [84]. As shown in **Figure 1**, the hypothalamic melanocortin system comprises the vital feeding regulatory neural circuitry, which consists of two groups of neurons, the first group expresses neuropeptide Y (**NPY**) and agouti-related protein (**AgRP**) while the second group expresses proopiomelanocortin (**POMC**), a precursor containing α-melanocyte-stimulating hormone. Stimulation of NPY/AgRP-expressing (anabolic) neurons mediates a net increase in feed intake and energy storage, whereas activation of the POMC-expressing (catabolic) neurons results in a net decrease in energy intake and storage. Initiation of AMPK in the hypothalamus in response to lowered energy status stimulates the activity of the NPY/AgRP-expressing (anabolic) neurons and thus leads to increased feed intake and reduced energy expenditure, which work together to increase energy status. On the other hand, activation of mTOR causes increased activity of the POMC-expressing (catabolic) neurons, which in turn causes a reduction in feed intake as a result of the presence of increased energy expenditure, thereby promoting the utilisation of energy for maintenance, growth, and reproduction. Thus, balance in the activity of hypothalamic melanocortin system

neurons is what ultimately determines feed intake considering dietary energy concentration

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However, reports and research on the influence of dietary energy intake on feed intake in poultry have been conflicting. These inconsistencies could be due to differences in genotype/ strain, environmental influence, stocking density, size of bird used, among other factors [81]. It is worthy to note that low-mass birds such as laying hens because of their size tend to adjust their feed intake in response to dietary energy concentration effectively than heavier birds such as broilers that maintain a constant feed intake, irrespective of the dietary energy concentration except this is limited by the gut content or other physiological factors [1]. Although there is a topic of great debate and discussion, a great number of research have reported the effect of high or low dietary energy in increasing or decreasing the feed intake in broiler chickens. It is well documented that most broiler chickens and laying hens tend to eat to satisfy their energy requirements or that they will consume a reduced amount of a feed greater in energy content than the one with a reduced energy concentration [87–89]. For instance, an earlier report by Sheriff et al. [90] indicated a higher feed consumption in broilers fed with low-energy diet. Moraes et al. [91] reported that high ME content results in low feed intake in laying hens. Almeida et al. [92] agreed with Moraes et al. [91] by also concluding that high dietary energy concentration led to a reduction in feed intake of commercial laying hen. Harms et al. [93] also observed that hens receiving the low-energy diet consumed signifi-

Van Krimpen et al. [94] concluded that hens that are fed low-energy diets or diets that are high in non-starch polysaccharides (NSP) spend more time on feed, compared with hens that were fed the normal control diets. Based on these facts, the authors concluded that laying hens adjust more rapidly to a decrease in dietary energy than to an increase in dietary energy. Compared to research results obtained using broilers and laying hens where an increase in dietary energy resulted to a decrease in feed intake and vice versa, Mbajiorgu et al. [81] observed an increase in feed intake when indigenous Venda chickens were fed increased dietary energy level. This difference in response between broiler chickens and laying hens compared to indigenous Venda chickens was attributed to the difference in intrinsic genetic limitations inherent in indigenous Venda chickens that may have led to the loss of sensitivity to influence feed intake when dietary energy regulatory strategy is applied [95]. Although there is a dearth of research on the nonsignificant effect of dietary energy concentration on feed intake of laying hens. Rather there are more consistent reports that laying hens can respond more effectively to dietary energy concentration on feed intake, unlike genetically improved broiler chickens. On the other hand, there are several reports that dietary energy intake did not affect feed intake especially in genetically modified broilers chickens. For instance, Araújo et al. [96] reported that there was no significant difference observed in feed intake among broilers fed high- and low-energy diets. A similar result was observed by Richards [80], who concluded that there was no effect on feed intake when varying concentration of dietary energy was administered on genetically improved broilers. Rosa et al. [97] also reported that feed intake was not affected by two different genetic broiler chicken groups. Richards and Proszkowiec-Weglarz [85] reported that modern commercial broiler breeders do not adequately control voluntary feed intake to meet their energy requirements and maintain energy balance. These authors thus advised that feeding must be limited in these birds

and a resultant improvement in whole-body energy balance and body weight.

cantly more feed than hens receiving the control and high-energy diets.

**Figure 1.** Diagram showing hypothalamic response in regulating feed intake when dietary energy intake is reduced or increased in poultry. Adopted and slightly modified from Bungo et al. [86]. NPY = neuropeptide Y; AGPR = agoutirelated protein; POMC = pro-opiomelanocortin; α MSH = α-melanocyte – stimulating hormone; ARC = arcuate nucleus, + = activate; − = inhibit.

neurons is what ultimately determines feed intake considering dietary energy concentration and a resultant improvement in whole-body energy balance and body weight.

However, reports and research on the influence of dietary energy intake on feed intake in poultry have been conflicting. These inconsistencies could be due to differences in genotype/ strain, environmental influence, stocking density, size of bird used, among other factors [81]. It is worthy to note that low-mass birds such as laying hens because of their size tend to adjust their feed intake in response to dietary energy concentration effectively than heavier birds such as broilers that maintain a constant feed intake, irrespective of the dietary energy concentration except this is limited by the gut content or other physiological factors [1]. Although there is a topic of great debate and discussion, a great number of research have reported the effect of high or low dietary energy in increasing or decreasing the feed intake in broiler chickens. It is well documented that most broiler chickens and laying hens tend to eat to satisfy their energy requirements or that they will consume a reduced amount of a feed greater in energy content than the one with a reduced energy concentration [87–89]. For instance, an earlier report by Sheriff et al. [90] indicated a higher feed consumption in broilers fed with low-energy diet. Moraes et al. [91] reported that high ME content results in low feed intake in laying hens. Almeida et al. [92] agreed with Moraes et al. [91] by also concluding that high dietary energy concentration led to a reduction in feed intake of commercial laying hen. Harms et al. [93] also observed that hens receiving the low-energy diet consumed significantly more feed than hens receiving the control and high-energy diets.

Van Krimpen et al. [94] concluded that hens that are fed low-energy diets or diets that are high in non-starch polysaccharides (NSP) spend more time on feed, compared with hens that were fed the normal control diets. Based on these facts, the authors concluded that laying hens adjust more rapidly to a decrease in dietary energy than to an increase in dietary energy. Compared to research results obtained using broilers and laying hens where an increase in dietary energy resulted to a decrease in feed intake and vice versa, Mbajiorgu et al. [81] observed an increase in feed intake when indigenous Venda chickens were fed increased dietary energy level. This difference in response between broiler chickens and laying hens compared to indigenous Venda chickens was attributed to the difference in intrinsic genetic limitations inherent in indigenous Venda chickens that may have led to the loss of sensitivity to influence feed intake when dietary energy regulatory strategy is applied [95]. Although there is a dearth of research on the nonsignificant effect of dietary energy concentration on feed intake of laying hens. Rather there are more consistent reports that laying hens can respond more effectively to dietary energy concentration on feed intake, unlike genetically improved broiler chickens. On the other hand, there are several reports that dietary energy intake did not affect feed intake especially in genetically modified broilers chickens. For instance, Araújo et al. [96] reported that there was no significant difference observed in feed intake among broilers fed high- and low-energy diets. A similar result was observed by Richards [80], who concluded that there was no effect on feed intake when varying concentration of dietary energy was administered on genetically improved broilers. Rosa et al. [97] also reported that feed intake was not affected by two different genetic broiler chicken groups. Richards and Proszkowiec-Weglarz [85] reported that modern commercial broiler breeders do not adequately control voluntary feed intake to meet their energy requirements and maintain energy balance. These authors thus advised that feeding must be limited in these birds

**Figure 1.** Diagram showing hypothalamic response in regulating feed intake when dietary energy intake is reduced or increased in poultry. Adopted and slightly modified from Bungo et al. [86]. NPY = neuropeptide Y; AGPR = agoutirelated protein; POMC = pro-opiomelanocortin; α MSH = α-melanocyte – stimulating hormone; ARC = arcuate nucleus,

all information and generating the appropriate responses in feed intake and energy requirement needed to maintain energy homeostasis [84]. As shown in **Figure 1**, the hypothalamic melanocortin system comprises the vital feeding regulatory neural circuitry, which consists of two groups of neurons, the first group expresses neuropeptide Y (**NPY**) and agouti-related protein (**AgRP**) while the second group expresses proopiomelanocortin (**POMC**), a precursor containing α-melanocyte-stimulating hormone. Stimulation of NPY/AgRP-expressing (anabolic) neurons mediates a net increase in feed intake and energy storage, whereas activation of the POMC-expressing (catabolic) neurons results in a net decrease in energy intake and storage. Initiation of AMPK in the hypothalamus in response to lowered energy status stimulates the activity of the NPY/AgRP-expressing (anabolic) neurons and thus leads to increased feed intake and reduced energy expenditure, which work together to increase energy status. On the other hand, activation of mTOR causes increased activity of the POMC-expressing (catabolic) neurons, which in turn causes a reduction in feed intake as a result of the presence of increased energy expenditure, thereby promoting the utilisation of energy for maintenance, growth, and reproduction. Thus, balance in the activity of hypothalamic melanocortin system

+ = activate; − = inhibit.

126 Animal Husbandry and Nutrition

using other feed intake regulatory strategies to avoid overconsumption, ascites and excessive fattening during production since dietary energy concentration does not influence feed intake in these breeds of birds.

quality, and affects consumer acceptance [107]. In the modern broiler industry, carcass fat is always considered to be an unfavourable characteristic [108], as it decreases feed efficiency and carcass yield; moreover, it leads to rejection of the broiler meat by the consumers [109, 110]. However, fatty acids and overall fat, both in muscle or adipose tissue, impact vitally on many different areas of meat quality and are necessary to the nutritional value of meat [111]. Additionally, the development of flavour in meat is significantly affected by the lipids of fatty tissue. Lipids impact flavour through their influence on flavour generation, flavour perception (mouth-feel, aroma and taste) and flavour stability. Tumova and Teimouri [110] and Lawrence and Fowler [112] reported that high densities of linoleic acid in the fatty tissue could have a remarkable impact on flavour. Apart from the problem of fat deposition, there is a tendency for high mortality as well as development of metabolic diseases and skeletal disorders [110].

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**8. Various strategies employed to manage dietary energy intake**

cost of production for broiler farmers and hatcheries will also be discussed.

Reduction in abdominal fat is a current goal in poultry industry so as to improve the efficiency of diets and to provide a less fat-laden meat product for consumers. Different nutritional strategies provide an opportunity to reduce production costs and at the same time, improve carcass quality in broiler chickens. Lowering the dietary energy level has been used to achieve the reduction in abdominal fat deposition. A study by Rosa et al. [97] evaluated the effect of energy intake and broiler genotype on performance, carcass yield, and fat deposition in two different genetic groups of broilers and reported that genetic improvement had a significant effect on broiler energy metabolism, and that abdominal fat decreased with low energy intake

**8.1. Nutritional strategies used to manage dietary energy intake**

As discussed earlier in this chapter, high or low dietary energy content can lower or increase feed intake [69]. Low feed intake as a result of high energy content (leading to inadequate intake of other vital nutrients) has been reported to result in poor performance. In most cases, high dietary energy intake causes high fat deposition with a resultant poor quality endproduct and increased mortality rate. On the other hand, low dietary energy intake has been reported to result in low energy storage, inability to achieve homeostasis and reduced body weight of poultry birds [101, 110]. Therefore, practices aimed at managing dietary energy will aid in ensuring adequate feed intake with a resultant improvement in performance, product quality as well as reduced cost of poultry production. For many decades, meat type broiler and broiler breeder farmers have knowingly and unknowingly used different methods individually or collectively to manage dietary energy intake. Examples of these practices include nutritional strategies (use of high or low energy and fibre diets, pelleting as well as the use of microbial enzymes); use of genetically improved breeds; feeding practices (panned restriction feeding system or *ad libitum* feeding practice); type of rearing system used (intensive housing system, free ranging system or semi-intensive system), and disease prevention practices [1, 81]. These practices will be briefly discussed in this section. The positive or negative effect of these practices as reported by various researchers will be concisely discussed. The application of these practices to manage dietary energy intake to improve productivity and reduce the

From the aforementioned, reports on regulating feed intake through dietary energy intake have been inconsistent. These contradictions could be attributed to the influences of several factors as mentioned in this chapter. Factors such as genotype, environment, variability in stocking density, and so on must be kept uniform with dietary energy concentration being a major source of variation for future variation. More research needs to be geared towards confirming or considering the effects of other nutrients and ANF on energy concentration as regards its efficacy on feed intake regulation needs to be considered. The effect of size with regard to the response of heavy or light breeds of birds to dietary energy concentration and its effects on the amount of feed these birds consume. Thus, a better understanding of the interaction of dietary energy concentration with other factors will go a long way to understand the mechanism of how dietary energy intake affects feed intake and to what degree/level feed intake can be influenced in poultry birds. However, more reports favour the fact that dietary energy regulates feed intake more in laying hens and to some extent in broilers. The differences that have occurred between broilers and laying hens in terms of the response of these birds to feed intake according to dietary energy intake was explained by Denbow [98]. The author stated that due to years of genetic selection for improved growth in broiler chickens, the various mechanisms that control feed intake in broiler chickens have altered compared to laying chickens that have not been selected for growth. Invariably, the author recommended the need for comparative studies to investigate the mechanisms involved in feed intake regulation for broiler chickens that have been selected for growth against laying chickens that have not been selected for growth.

## **7. Effect and implication of imbalance in energy intake in poultry**

Broiler chickens have been genetically bred for increased weight gain, feed efficiency, growth rate, and breast muscle weight to meet the requirements of consumers [99]. This process has produced modern commercial chicken lines with a faster growth rate, better breast meat yield and feed conversion, as well as higher body fat compared with unselected lines [100]. Dietary energy is essential for maintenance of the chicken's normal metabolism and meat yield. However, when the amount of energy consumed by the bird exceeds that required for the purpose of maintenance and growth, the remainder is deposited as fat [101]. This situation may be further aided by the imbalance in nutrients in the diets, especially the energy to protein ratio [102, 103]. After hatching, birds are expected to increase their body weights over time and the amount and ratios of body protein and fat augment at various rates [104]; however, there is potential to deposit fat faster at later phases [102]. More so, the excessive fat in modern chicken strains is one of the most important challenges facing the poultry industry [105]. For example, Choct et al. [106] found that modern broilers contain 15–20% fat, and >85% of this fat is not required for physiological body processes. In general, disproportionate fat laydown is an undesirable trait for producers and consumers alike because it is considered a waste of dietary energy and a product with little economic value, which reduces carcass yield, and quality, and affects consumer acceptance [107]. In the modern broiler industry, carcass fat is always considered to be an unfavourable characteristic [108], as it decreases feed efficiency and carcass yield; moreover, it leads to rejection of the broiler meat by the consumers [109, 110]. However, fatty acids and overall fat, both in muscle or adipose tissue, impact vitally on many different areas of meat quality and are necessary to the nutritional value of meat [111]. Additionally, the development of flavour in meat is significantly affected by the lipids of fatty tissue. Lipids impact flavour through their influence on flavour generation, flavour perception (mouth-feel, aroma and taste) and flavour stability. Tumova and Teimouri [110] and Lawrence and Fowler [112] reported that high densities of linoleic acid in the fatty tissue could have a remarkable impact on flavour. Apart from the problem of fat deposition, there is a tendency for high mortality as well as development of metabolic diseases and skeletal disorders [110].

## **8. Various strategies employed to manage dietary energy intake**

using other feed intake regulatory strategies to avoid overconsumption, ascites and excessive fattening during production since dietary energy concentration does not influence feed intake

From the aforementioned, reports on regulating feed intake through dietary energy intake have been inconsistent. These contradictions could be attributed to the influences of several factors as mentioned in this chapter. Factors such as genotype, environment, variability in stocking density, and so on must be kept uniform with dietary energy concentration being a major source of variation for future variation. More research needs to be geared towards confirming or considering the effects of other nutrients and ANF on energy concentration as regards its efficacy on feed intake regulation needs to be considered. The effect of size with regard to the response of heavy or light breeds of birds to dietary energy concentration and its effects on the amount of feed these birds consume. Thus, a better understanding of the interaction of dietary energy concentration with other factors will go a long way to understand the mechanism of how dietary energy intake affects feed intake and to what degree/level feed intake can be influenced in poultry birds. However, more reports favour the fact that dietary energy regulates feed intake more in laying hens and to some extent in broilers. The differences that have occurred between broilers and laying hens in terms of the response of these birds to feed intake according to dietary energy intake was explained by Denbow [98]. The author stated that due to years of genetic selection for improved growth in broiler chickens, the various mechanisms that control feed intake in broiler chickens have altered compared to laying chickens that have not been selected for growth. Invariably, the author recommended the need for comparative studies to investigate the mechanisms involved in feed intake regulation for broiler chickens that have been selected for growth against laying chickens that

**7. Effect and implication of imbalance in energy intake in poultry**

Broiler chickens have been genetically bred for increased weight gain, feed efficiency, growth rate, and breast muscle weight to meet the requirements of consumers [99]. This process has produced modern commercial chicken lines with a faster growth rate, better breast meat yield and feed conversion, as well as higher body fat compared with unselected lines [100]. Dietary energy is essential for maintenance of the chicken's normal metabolism and meat yield. However, when the amount of energy consumed by the bird exceeds that required for the purpose of maintenance and growth, the remainder is deposited as fat [101]. This situation may be further aided by the imbalance in nutrients in the diets, especially the energy to protein ratio [102, 103]. After hatching, birds are expected to increase their body weights over time and the amount and ratios of body protein and fat augment at various rates [104]; however, there is potential to deposit fat faster at later phases [102]. More so, the excessive fat in modern chicken strains is one of the most important challenges facing the poultry industry [105]. For example, Choct et al. [106] found that modern broilers contain 15–20% fat, and >85% of this fat is not required for physiological body processes. In general, disproportionate fat laydown is an undesirable trait for producers and consumers alike because it is considered a waste of dietary energy and a product with little economic value, which reduces carcass yield, and

in these breeds of birds.

128 Animal Husbandry and Nutrition

have not been selected for growth.

As discussed earlier in this chapter, high or low dietary energy content can lower or increase feed intake [69]. Low feed intake as a result of high energy content (leading to inadequate intake of other vital nutrients) has been reported to result in poor performance. In most cases, high dietary energy intake causes high fat deposition with a resultant poor quality endproduct and increased mortality rate. On the other hand, low dietary energy intake has been reported to result in low energy storage, inability to achieve homeostasis and reduced body weight of poultry birds [101, 110]. Therefore, practices aimed at managing dietary energy will aid in ensuring adequate feed intake with a resultant improvement in performance, product quality as well as reduced cost of poultry production. For many decades, meat type broiler and broiler breeder farmers have knowingly and unknowingly used different methods individually or collectively to manage dietary energy intake. Examples of these practices include nutritional strategies (use of high or low energy and fibre diets, pelleting as well as the use of microbial enzymes); use of genetically improved breeds; feeding practices (panned restriction feeding system or *ad libitum* feeding practice); type of rearing system used (intensive housing system, free ranging system or semi-intensive system), and disease prevention practices [1, 81]. These practices will be briefly discussed in this section. The positive or negative effect of these practices as reported by various researchers will be concisely discussed. The application of these practices to manage dietary energy intake to improve productivity and reduce the cost of production for broiler farmers and hatcheries will also be discussed.

#### **8.1. Nutritional strategies used to manage dietary energy intake**

Reduction in abdominal fat is a current goal in poultry industry so as to improve the efficiency of diets and to provide a less fat-laden meat product for consumers. Different nutritional strategies provide an opportunity to reduce production costs and at the same time, improve carcass quality in broiler chickens. Lowering the dietary energy level has been used to achieve the reduction in abdominal fat deposition. A study by Rosa et al. [97] evaluated the effect of energy intake and broiler genotype on performance, carcass yield, and fat deposition in two different genetic groups of broilers and reported that genetic improvement had a significant effect on broiler energy metabolism, and that abdominal fat decreased with low energy intake (2950 kcal/kg) compared to the other diets. In another study, Choct et al. [106] examined the influence of different fat sources at two dietary levels on lean growth in broilers and concluded that the addition of fish oil to broiler diets reduced the abdominal fat pad weights. Fish oil contains long-chain polyunsaturated fatty acids, which enhance low-density lipoprotein and triglyceride levels while increasing glucose uptake into the muscle tissue in blood and lessening the negative effects of the immune system on protein breakdown. However, one consideration with the use of fish oil is its development of off-flavour in bird diets and the reduced shelf life of the chicken meat, which can be improved with the use of preserving agents and antioxidants [113]. According to Leeson [114], the success of the use of lower-energy diets is in the ability to predict change in feed intake and corresponding modification to all other nutrients in the diet, hence, a reduced dietary energy intake may be triggered by excess or imbalance of other nutrients in broiler diet. Leeson [114] further proposed that when all nutrients are tied to dietary energy, broilers are able to remarkably maintain energy intake when confronted with a major reduction in dietary energy concentration. More so, a recent study at the University of New England tested the effect of dietary fibre and energy levels on energy intake. It was observed that low while an optimum energy level in diet in combination with high dietary fibre inclusion reduced abdominal fat and cost in broilers as shown in **Table 3** [115]. Another nutritional strategy that has been used to manage dietary energy intake in broiler chickens is supplementation with exogenous that target energy-yielding substrates. **Table 4** shows examples of various carbohydrate- and lipid-targeting enzymes as well as their targeted substrates and energy sources. Such exogenous enzymes aid in the release of trapped dietary energy, especially energy sources such as wheat, rye, barley and oat that are high in NSP [116]. Exogenous carbohydrase enzymes have been reported to reduce or eliminate the effect of NSP, thereby furnishing more nutrients. Increased feed consumption in broilers leads to increased dietary energy intake. In the same vein, increased dietary intake leads to increased fat deposition and poor product quality. Based on this fact, most poultry farmers have imbibed the practice of reducing the quantity of feed offered to their birds and simultaneously adding exogenous enzymes to help release nutrients bound by antinutritional factors. This practice has been reported to result in broilers that grow faster and also have leaner meat [117].

#### **8.2. Managing dietary energy intake in broilers through selective genetic improvement**

High carcass fat is considered unfavourable by consumers in most parts of the world. Based on this fact, breeding programs have been developed with the aim of selecting against high fat deposition in broiler carcass in order to improve the quality of the product [118]. Modern broilers have been genetically selected to have significantly reduced fat deposition and also have better weight gain and FCR as a result of significantly masking the effect of dietary energy content in the diet [119]. Because of the tremendous success achieved through artificial selection of broiler chickens, there has been a reduction in total feed and energy required to raise broiler chickens to slaughter or market weight. Genetically, lean birds have better energy use efficiency [120]. This achievement has also resulted to a reduction in cost of production [121]. It is worthy to note, however, that genetic improvement of broilers with the aim of controlling the effect of high or low dietary energy intake could be influenced by several factors such as: nutrition, health of the

bird, environment, and so on. The authors of Refs. [1, 97, 122] reported that the genetic make-up of a broiler bird is not the sole reason for the success achieved in managing dietary energy intake by some broiler producers. The authors suggested that the success achieved in this area may be as a result of the combination of genetics and other factors such as environmental influence,

**Table 3.** Feed intake, feed utilisation, meat yield and economic analysis of broiler chickens fed finisher diets differing in

nutrition, management practices, age, sex of the birds and disease prevention strategies.

*Feed consumption and utilisation (0–35 d)*

*Meat yield (g/kg live weight) (35 d)*

**Energy content**

**Energy content**

Low Optimum 1.25 0.57 Low Low 1.16 0.54 Medium Optimum 1.23 0.58 -Medium Low 1.19 0.60 High Optimum 1.30 0.62 High Low 1.21 0.59

**Live weight**

**Feed cost (\$/bird)**

**Energy content** **Feed intake (g/b) Body** 

**Carcass weight**

Low Optimum 2248.4 1678.3 263.9 216.4 416.5 30.6 Low Low 2201.0 1630.0 250.1 215.5 392.2 23.0 Medium Optimum 2179.2 1629.3 250.9 213.5 395.0 25.1 Medium Low 2093.2 1562.3 240.4 199.9 391.8 22.6 High Optimum 2201.2 1621.2 244.2 207.5 413.4 22.2 High Low 2250.6 1684.0 278.3 211.2 410.9 24.6

> **Feed cost (\$/kg gain)**

Low Optimum 3432.0 2250.9 2209.6 1.55 Low Low 3248.0 2177.2 2136.1 1.52 Medium Optimum 3332.9 2143.6 2102.2 1.59 Medium Low 3337.7 2026.3 1984.7 1.68 High Optimum 3510.5 2142.9 2101.7 1.67 High Low 3324.7 2103.8 2062.8 1.61

**weight (g/b)**

Managing Dietary Energy Intake by Broiler Chickens to Reduce Production Costs and Improve…

**Body weight gain (g/b)**

**Thigh Drumstick Breast** 

**FCR**

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**(skinless)**

**Abdominal fat** 

**pad**

**Dietary fibre content**

**Dietary fibre content**

*Economic analysis* **Dietary fibre content**

Source: Chen [115].

fibre and energy contents.


(2950 kcal/kg) compared to the other diets. In another study, Choct et al. [106] examined the influence of different fat sources at two dietary levels on lean growth in broilers and concluded that the addition of fish oil to broiler diets reduced the abdominal fat pad weights. Fish oil contains long-chain polyunsaturated fatty acids, which enhance low-density lipoprotein and triglyceride levels while increasing glucose uptake into the muscle tissue in blood and lessening the negative effects of the immune system on protein breakdown. However, one consideration with the use of fish oil is its development of off-flavour in bird diets and the reduced shelf life of the chicken meat, which can be improved with the use of preserving agents and antioxidants [113]. According to Leeson [114], the success of the use of lower-energy diets is in the ability to predict change in feed intake and corresponding modification to all other nutrients in the diet, hence, a reduced dietary energy intake may be triggered by excess or imbalance of other nutrients in broiler diet. Leeson [114] further proposed that when all nutrients are tied to dietary energy, broilers are able to remarkably maintain energy intake when confronted with a major reduction in dietary energy concentration. More so, a recent study at the University of New England tested the effect of dietary fibre and energy levels on energy intake. It was observed that low while an optimum energy level in diet in combination with high dietary fibre inclusion reduced abdominal fat and cost in broilers as shown in **Table 3** [115]. Another nutritional strategy that has been used to manage dietary energy intake in broiler chickens is supplementation with exogenous that target energy-yielding substrates. **Table 4** shows examples of various carbohydrate- and lipid-targeting enzymes as well as their targeted substrates and energy sources. Such exogenous enzymes aid in the release of trapped dietary energy, especially energy sources such as wheat, rye, barley and oat that are high in NSP [116]. Exogenous carbohydrase enzymes have been reported to reduce or eliminate the effect of NSP, thereby furnishing more nutrients. Increased feed consumption in broilers leads to increased dietary energy intake. In the same vein, increased dietary intake leads to increased fat deposition and poor product quality. Based on this fact, most poultry farmers have imbibed the practice of reducing the quantity of feed offered to their birds and simultaneously adding exogenous enzymes to help release nutrients bound by antinutritional factors. This practice

has been reported to result in broilers that grow faster and also have leaner meat [117].

High carcass fat is considered unfavourable by consumers in most parts of the world. Based on this fact, breeding programs have been developed with the aim of selecting against high fat deposition in broiler carcass in order to improve the quality of the product [118]. Modern broilers have been genetically selected to have significantly reduced fat deposition and also have better weight gain and FCR as a result of significantly masking the effect of dietary energy content in the diet [119]. Because of the tremendous success achieved through artificial selection of broiler chickens, there has been a reduction in total feed and energy required to raise broiler chickens to slaughter or market weight. Genetically, lean birds have better energy use efficiency [120]. This achievement has also resulted to a reduction in cost of production [121]. It is worthy to note, however, that genetic improvement of broilers with the aim of controlling the effect of high or low dietary energy intake could be influenced by several factors such as: nutrition, health of the

**8.2. Managing dietary energy intake in broilers through selective genetic** 

**improvement**

130 Animal Husbandry and Nutrition

**Table 3.** Feed intake, feed utilisation, meat yield and economic analysis of broiler chickens fed finisher diets differing in fibre and energy contents.

bird, environment, and so on. The authors of Refs. [1, 97, 122] reported that the genetic make-up of a broiler bird is not the sole reason for the success achieved in managing dietary energy intake by some broiler producers. The authors suggested that the success achieved in this area may be as a result of the combination of genetics and other factors such as environmental influence, nutrition, management practices, age, sex of the birds and disease prevention strategies.


programs has been the loss of ability by broilers to control feed intake to adequately meet up with maintenance, growth, and reproductive function [133]. Based on this fact, broilers tend to overfeed, and this uncontrollable feeding habit has been reported to cause nutritional, metabolic and health problems related to obesity. To manage this problem, most farmers have resorted to the subjecting of their meat or breeder broilers to planned feed restriction. Early age planned feeding restriction practice in meat or breeder broilers is geared towards ensuring that appropriate body composition and weight are achieved at important phases of the production cycle [133]. The success of a planned feed restriction in managing dietary energy intake depends on quantity of feed and timing of the feed restriction. This statement is in agreement with the report of Chenxi et al. [134] who concluded that feed restriction done by dilution of dietary energy and protein by 10% from 8 to 14 (early age planned feed restriction) is a suitable feeding program. The authors further explained that compared to the control group, there was no significant difference in body weight FCR and feed intake at 42 days. Chen et al. [135] also observed that 30% dietary energy restriction resulted in a decrease in fat deposition and an improvement in body weight and FCR at later phase of life. Bruggenan et al. [136] suggested that restriction applied at 7–15 weeks of age followed by either *ad libitum* feeding or continued feed restriction controlled feed and nutrient intake which was the best

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for improving reproductive performance in broiler breeder females.

**8.5. Rearing system as a means of managing dietary energy intake**

mash diet is properly/uniformly mixed.

**8.4. Feed processing strategies aimed at managing dietary energy intake in poultry**

Birds try to make adjustments geared towards controlling the amount of energy they consume. Feed processing is an important strategy used by poultry producers to manage dietary energy intake. The form in which feed is presented to broiler birds can affect the energy and nutrient (energy, protein, vitamins and mineral) intake. Feeding broilers with mash leads to ingredient selection, which results in poor performance [137]. According to Davis et al. [138] cited by Amerah et al. [139], poultry tends to select maize particles while ignoring soybean (protein source needed for growth and tissue build up), which would affect the intake of amino acids, vitamins and minerals, when fed with mash diets. The selection of maize feed particles tends to increase the dietary energy intake, with a resultant increase in fat deposition. This condition leads to poor growth and poor product quality in broilers. To solve this problem, broiler producers now use crumbles at the starter phase, and pellets at grower and finisher phases. This strategy tends to eliminate the issue of feed ingredient particle selection noticed when mash diets are fed to broilers. In laying hens, excessive fat deposition hinders egg production and thus feeding of mash to layers is a common practice, especially if the

The increasing global demand by broiler meat and egg consumers for high-quality poultry products has necessitated the drive of breeders and producers towards meeting this demand at the least possible cost. In an effort to meet this demand, farmers are adopting different housing and rearing strategies (a deviation from the normal intensive system) such as free range and semi-intensive [140, 141]. It is well documented that the environment under which

**Table 4.** Different types of commercially available energy-targeting enzymes used to manage dietary energy.

#### **8.3. Feeding practices used to manage dietary energy intake**

Various practices such as restricted feeding and *ad libitum* feeding have been reported to influence dietary energy intake in meat broilers, laying hens as well as in broiler breeders [123]. These practices could have negative or positive effect on broiler performance and cost of production. Several researchers have reported the advantages and disadvantages of these feeding strategies [124–129]. For instance, Acar et al. [125] and Butzen et al. [128] both agreed that excessive fat deposition, ascites, sudden death syndrome as well as various metabolic disorders and disease in broiler can be reduced through planned feed restriction practice. To achieve success in managing dietary energy intake using these practices, adequate knowledge and skills in administering these strategies become key factors towards using them to achieve the right dietary energy intake in meat broilers, laying hens as well as in rearing broiler breeders.

#### *8.3.1. Ad libitum feeding as a tool in controlling energy intake*

*Ad libitum* feeding is defined as an animal husbandry practice in which animals are allowed unlimited access to feed on free choice basis [128, 130]. Feeding meat and breeder broilers *ad libitum* lead to increased feed and dietary energy intake and fat deposition compared to birds on restricted feeding [131]. According to Heck et al. [132], energy conversion (kJ/g egg) from 32 to 40 weeks of age was much higher in the broiler breeders on *ad libitum* feeding group than in broiler breeders that were on restricted feeding plan. The authors further explained that sexual maturity was delayed by 6 weeks in restricted breeders compared to *ad libitum* fed broiler breeders that started to lay at 20 weeks. On the contrary, the authors also reported that broiler breeder hens fed *ad libitum*, had low egg production and a high proportion of defective eggs, which was largely rectified by feed restriction.

#### *8.3.2. Using feed restriction to manage energy intake*

Feed restriction involves a calculated or planned practice of decreasing the amount of feed being offered to broiler birds with the aim of decreasing feed intake over a certain time interval in an attempt to slow the rate of weight gain, fat deposition and various metabolic disorders associated to excessive feeding. Contemporary commercial broilers are the product of intensive genetic selection for rapid growth. An unpremeditated result of these genetic selection programs has been the loss of ability by broilers to control feed intake to adequately meet up with maintenance, growth, and reproductive function [133]. Based on this fact, broilers tend to overfeed, and this uncontrollable feeding habit has been reported to cause nutritional, metabolic and health problems related to obesity. To manage this problem, most farmers have resorted to the subjecting of their meat or breeder broilers to planned feed restriction. Early age planned feeding restriction practice in meat or breeder broilers is geared towards ensuring that appropriate body composition and weight are achieved at important phases of the production cycle [133]. The success of a planned feed restriction in managing dietary energy intake depends on quantity of feed and timing of the feed restriction. This statement is in agreement with the report of Chenxi et al. [134] who concluded that feed restriction done by dilution of dietary energy and protein by 10% from 8 to 14 (early age planned feed restriction) is a suitable feeding program. The authors further explained that compared to the control group, there was no significant difference in body weight FCR and feed intake at 42 days. Chen et al. [135] also observed that 30% dietary energy restriction resulted in a decrease in fat deposition and an improvement in body weight and FCR at later phase of life. Bruggenan et al. [136] suggested that restriction applied at 7–15 weeks of age followed by either *ad libitum* feeding or continued feed restriction controlled feed and nutrient intake which was the best for improving reproductive performance in broiler breeder females.

#### **8.4. Feed processing strategies aimed at managing dietary energy intake in poultry**

**8.3. Feeding practices used to manage dietary energy intake**

**Enzyme Substrate targeted Mode of action Feed ingredient of interest** β-Glucanase β-Glucans Oats, rye and barley

Xylanases Arabinoxylans Wheat, triticale, barley and rye Amylase Starch Cereal grains, roots and tubers Lipase Lipid Lipid in feed ingredient

*8.3.1. Ad libitum feeding as a tool in controlling energy intake*

eggs, which was largely rectified by feed restriction.

*8.3.2. Using feed restriction to manage energy intake*

broiler breeders.

Adopted from Ravindran [116].

132 Animal Husbandry and Nutrition

Various practices such as restricted feeding and *ad libitum* feeding have been reported to influence dietary energy intake in meat broilers, laying hens as well as in broiler breeders [123]. These practices could have negative or positive effect on broiler performance and cost of production. Several researchers have reported the advantages and disadvantages of these feeding strategies [124–129]. For instance, Acar et al. [125] and Butzen et al. [128] both agreed that excessive fat deposition, ascites, sudden death syndrome as well as various metabolic disorders and disease in broiler can be reduced through planned feed restriction practice. To achieve success in managing dietary energy intake using these practices, adequate knowledge and skills in administering these strategies become key factors towards using them to achieve the right dietary energy intake in meat broilers, laying hens as well as in rearing

**Table 4.** Different types of commercially available energy-targeting enzymes used to manage dietary energy.

*Ad libitum* feeding is defined as an animal husbandry practice in which animals are allowed unlimited access to feed on free choice basis [128, 130]. Feeding meat and breeder broilers *ad libitum* lead to increased feed and dietary energy intake and fat deposition compared to birds on restricted feeding [131]. According to Heck et al. [132], energy conversion (kJ/g egg) from 32 to 40 weeks of age was much higher in the broiler breeders on *ad libitum* feeding group than in broiler breeders that were on restricted feeding plan. The authors further explained that sexual maturity was delayed by 6 weeks in restricted breeders compared to *ad libitum* fed broiler breeders that started to lay at 20 weeks. On the contrary, the authors also reported that broiler breeder hens fed *ad libitum*, had low egg production and a high proportion of defective

Feed restriction involves a calculated or planned practice of decreasing the amount of feed being offered to broiler birds with the aim of decreasing feed intake over a certain time interval in an attempt to slow the rate of weight gain, fat deposition and various metabolic disorders associated to excessive feeding. Contemporary commercial broilers are the product of intensive genetic selection for rapid growth. An unpremeditated result of these genetic selection Birds try to make adjustments geared towards controlling the amount of energy they consume. Feed processing is an important strategy used by poultry producers to manage dietary energy intake. The form in which feed is presented to broiler birds can affect the energy and nutrient (energy, protein, vitamins and mineral) intake. Feeding broilers with mash leads to ingredient selection, which results in poor performance [137]. According to Davis et al. [138] cited by Amerah et al. [139], poultry tends to select maize particles while ignoring soybean (protein source needed for growth and tissue build up), which would affect the intake of amino acids, vitamins and minerals, when fed with mash diets. The selection of maize feed particles tends to increase the dietary energy intake, with a resultant increase in fat deposition. This condition leads to poor growth and poor product quality in broilers. To solve this problem, broiler producers now use crumbles at the starter phase, and pellets at grower and finisher phases. This strategy tends to eliminate the issue of feed ingredient particle selection noticed when mash diets are fed to broilers. In laying hens, excessive fat deposition hinders egg production and thus feeding of mash to layers is a common practice, especially if the mash diet is properly/uniformly mixed.

#### **8.5. Rearing system as a means of managing dietary energy intake**

The increasing global demand by broiler meat and egg consumers for high-quality poultry products has necessitated the drive of breeders and producers towards meeting this demand at the least possible cost. In an effort to meet this demand, farmers are adopting different housing and rearing strategies (a deviation from the normal intensive system) such as free range and semi-intensive [140, 141]. It is well documented that the environment under which a poultry are reared plays a pivotal role in the quality of the product. Environment and housing system influence feed intake with a corresponding effect on dietary energy intake. Two types of rearing system are mostly employed in poultry production and they include intensive housing system and free range system. However, in order to reduce the shortcomings of these two rearing systems, a rearing strategy known as semi-intensive system is gradually gaining popularity [140]. Although free range and semi-intensive rearing systems are mostly used for egg laying hens, the increasing demand by consumers for meat produced from organically reared broilers is driving the introduction of these rearing systems in meattype broiler production [141].

Increasing or decreasing dietary energy intake has been reported to influence feed intake with a corresponding effect on performance and cost of production. Results on the use of this method have been inconsistent. These inconsistencies are due to several factors, including genotype, diet composition, digestible nutrient contents, energy to protein ratio, feed form, feed processing, dietary energy sources, physical environment and disease. However, the progress achieved is also very encouraging. It is therefore necessary to explore the effect of the abovementioned factors on dietary energy intake and seek for innovative ways to mask the effect of these factors so as to have a more consistent outcome when dietary energy intake strategy is used to influence the cost of production and product quality of broiler chickens. Various strategies aimed at reducing dietary energy intake through the use of high fibre diet combined with enzyme is very promising in improving carcass quality and reduce cost.

Managing Dietary Energy Intake by Broiler Chickens to Reduce Production Costs and Improve…

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135

Emmanuel U. Ahiwe1,4, Apeh A. Omede1,2, Medani B. Abdallh1,3 and Paul A. Iji1,5\*

2 Department of Animal Production, Kogi State University, Anyigba, Nigeria 3 Department of Poultry Production, University of Khartoum, Khartoum, Sudan

1 School of Environmental and Rural Science, University of New England, Armidale,

4 Department of Animal Science and Technology, Federal University of Technology, Owerri,

[1] Ferket PR, Gernat AG. Factors that affect feed intake of meat birds: A review. International

[2] Skinner JT, Waldroup AL, Waldroup PW. Effects of dietary nutrient density on performance and carcass quality of broilers 42 to 49 days of age. The Journal of Applied

[3] Tewe OO, Egbunike GN. Utilization of cassava in non-ruminant feeding. In: Hahn SK, Reynolds L, Egbunike GN, editors. Cassava as Livestock Feed in Africa Addis Ababa:

[4] `Van der Klis JD, Kwakernaak C, Jansman A, Blok M. Energy in poultry diets: Adjusted AME or net energy. In: Proceedings of Australian Poultry Science Symposium. Vol. 21. Sydney, Australia; The Poultry Research Foundation (University of Sydney) and The

World's Poultry Science Association (Australian Branch); 2010. pp. 44-49

5 College of Agriculture, Fisheries and Forestry, Fiji National University, Koronivia, Fiji

\*Address all correspondence to: pauladeiji@gmail.com

Journal of Poultry Science. 2006;**5**(10):905-911

Poultry Research. 1992;**1**:367-372

IITA, Ibadan and ILCA. 1992. pp. 28-38

**Author details**

Australia

Nigeria

**References**

#### **8.6. Managing dietary energy intake by controlling lightening regime**

Light is a critical factor used to manipulate feed intake in broilers. By artificially increasing the length of time, the bird is subjected to light, its feed or dietary energy intake can be increased. On the other hand, lowered or total light-out tends to reduce feed intake in broilers. This fact is true because broilers tend to stop feeding once the light is off but resume feeding once the light is on. This technique has been employed in modern poultry systems to achieve optimum growth rates [142]. Intermittent lighting programs are routinely used by broiler producers. Buryse et al. [143] concluded that intermittent lighting program had a favourable effect on feed conversion and weight gain, with a decrease in fat deposition. Apeldoorn et al. [144] reported that the improvement in feed conversion with intermittent lighting programs was related to reduction in feed intake. This reduces the cost of production while growth rate and meat quality are unaltered. The author also showed that reduced feed efficiency was related to higher ME/GE utilisation.

#### **8.7. Disease prevention practices as a tool in controlling dietary energy intake**

Broilers in optimum health condition up to finisher phase have been reported to yield quality meat. Diseased birds tend to have reduced feed and dietary energy intake with a resultant decrease in meat, egg quality and mortality of poultry birds. The ability of a producer to effectively prevent disease or infections will go a long way to maintain feed and dietary energy intake and prevent unnecessary expenditure associated with purchase of drugs. Disease conditions tend to reduce feed intake and lead to malnutrition, which is a predisposing factor to various metabolic diseases [1]. Several disease prevention strategies such as the use of disease-free poultry birds, adherence to biosecurity, adequate and prompt vaccination when and if needed, isolation of sick birds, prevention of predators and potential disease-carrying vectors could go a long way to enable the birds to consume the right dietary energy content, leading to quality at least cost.

## **9. Conclusion**

Improving poultry meat quality as well as cutting down on the cost of broiler production has been some of the major objectives of most farmers, processors and researchers. To achieve these objectives, several strategies have been adopted, one of which is dietary energy management. Increasing or decreasing dietary energy intake has been reported to influence feed intake with a corresponding effect on performance and cost of production. Results on the use of this method have been inconsistent. These inconsistencies are due to several factors, including genotype, diet composition, digestible nutrient contents, energy to protein ratio, feed form, feed processing, dietary energy sources, physical environment and disease. However, the progress achieved is also very encouraging. It is therefore necessary to explore the effect of the abovementioned factors on dietary energy intake and seek for innovative ways to mask the effect of these factors so as to have a more consistent outcome when dietary energy intake strategy is used to influence the cost of production and product quality of broiler chickens. Various strategies aimed at reducing dietary energy intake through the use of high fibre diet combined with enzyme is very promising in improving carcass quality and reduce cost.

## **Author details**

a poultry are reared plays a pivotal role in the quality of the product. Environment and housing system influence feed intake with a corresponding effect on dietary energy intake. Two types of rearing system are mostly employed in poultry production and they include intensive housing system and free range system. However, in order to reduce the shortcomings of these two rearing systems, a rearing strategy known as semi-intensive system is gradually gaining popularity [140]. Although free range and semi-intensive rearing systems are mostly used for egg laying hens, the increasing demand by consumers for meat produced from organically reared broilers is driving the introduction of these rearing systems in meat-

Light is a critical factor used to manipulate feed intake in broilers. By artificially increasing the length of time, the bird is subjected to light, its feed or dietary energy intake can be increased. On the other hand, lowered or total light-out tends to reduce feed intake in broilers. This fact is true because broilers tend to stop feeding once the light is off but resume feeding once the light is on. This technique has been employed in modern poultry systems to achieve optimum growth rates [142]. Intermittent lighting programs are routinely used by broiler producers. Buryse et al. [143] concluded that intermittent lighting program had a favourable effect on feed conversion and weight gain, with a decrease in fat deposition. Apeldoorn et al. [144] reported that the improvement in feed conversion with intermittent lighting programs was related to reduction in feed intake. This reduces the cost of production while growth rate and meat quality are unaltered. The author also showed that reduced feed efficiency was related to higher ME/GE utilisation.

**8.6. Managing dietary energy intake by controlling lightening regime**

**8.7. Disease prevention practices as a tool in controlling dietary energy intake**

Broilers in optimum health condition up to finisher phase have been reported to yield quality meat. Diseased birds tend to have reduced feed and dietary energy intake with a resultant decrease in meat, egg quality and mortality of poultry birds. The ability of a producer to effectively prevent disease or infections will go a long way to maintain feed and dietary energy intake and prevent unnecessary expenditure associated with purchase of drugs. Disease conditions tend to reduce feed intake and lead to malnutrition, which is a predisposing factor to various metabolic diseases [1]. Several disease prevention strategies such as the use of disease-free poultry birds, adherence to biosecurity, adequate and prompt vaccination when and if needed, isolation of sick birds, prevention of predators and potential disease-carrying vectors could go a long way to enable the birds to consume the right dietary energy content,

Improving poultry meat quality as well as cutting down on the cost of broiler production has been some of the major objectives of most farmers, processors and researchers. To achieve these objectives, several strategies have been adopted, one of which is dietary energy management.

type broiler production [141].

134 Animal Husbandry and Nutrition

leading to quality at least cost.

**9. Conclusion**

Emmanuel U. Ahiwe1,4, Apeh A. Omede1,2, Medani B. Abdallh1,3 and Paul A. Iji1,5\*

\*Address all correspondence to: pauladeiji@gmail.com

1 School of Environmental and Rural Science, University of New England, Armidale, Australia

2 Department of Animal Production, Kogi State University, Anyigba, Nigeria

3 Department of Poultry Production, University of Khartoum, Khartoum, Sudan

4 Department of Animal Science and Technology, Federal University of Technology, Owerri, Nigeria

5 College of Agriculture, Fisheries and Forestry, Fiji National University, Koronivia, Fiji

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**Chapter 7**

**Provisional chapter**

**Current and Future Improvements in Livestock**

**Current and Future Improvements in Livestock** 

DOI: 10.5772/intechopen.73088

This study reviews the current and future trends in the improvements being made in livestock nutrition and feed resources. There had been continuous improvements in global livestock production for past decades. Most of the improvements have been in response to increasing human populations, urbanization, income growth, production system efficiency, and environmental sustainability. To meet up with the increasing global demand for livestock products was the role earmarked to be played by animal nutritionists in a manner that there would be optimization of feed efficiency to achieve more livestock products from less feed. There has been the development and adoption of biotechnological applications such as the feeding of genetically modified plants and the use of in-feed additives such as antibiotics. In the past decades, the livestock feed industry had been centered on the use of antibiotics as livestock growth promoters. However, there has also been the negative development of microbial antibiotic resistance with various countries promulgating laws and regulations to ban and discourage in-feed antibiotic applications in the livestock feed industry. Thus, present and future improvements in livestock nutrition and feed resources are now being directed at the use of approved probiotics and the

application of nanotechnology in livestock nutrition and feeding.

**Keywords:** improvements, livestock, nutrition, feeding, biotechnology

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

Nutrition could be a serious limitation to livestock production especially when feed resources are inadequate in both quality and quantity. Global livestock production over the years has increased consistently and brought about increases in animal numbers [1, 2]. However, these increases in the number of animals have not always been accompanied by an improved availability of livestock feed resources. These may result in overgrazing, erosion, reduced health,

**Nutrition and Feed Resources**

**Nutrition and Feed Resources**

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73088

Grace Opadoyin Tona

**Abstract**

**1. Introduction**

Grace Opadoyin Tona

**Provisional chapter**

## **Current and Future Improvements in Livestock Nutrition and Feed Resources Nutrition and Feed Resources**

**Current and Future Improvements in Livestock** 

DOI: 10.5772/intechopen.73088

Grace Opadoyin Tona Grace Opadoyin Tona Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73088

#### **Abstract**

This study reviews the current and future trends in the improvements being made in livestock nutrition and feed resources. There had been continuous improvements in global livestock production for past decades. Most of the improvements have been in response to increasing human populations, urbanization, income growth, production system efficiency, and environmental sustainability. To meet up with the increasing global demand for livestock products was the role earmarked to be played by animal nutritionists in a manner that there would be optimization of feed efficiency to achieve more livestock products from less feed. There has been the development and adoption of biotechnological applications such as the feeding of genetically modified plants and the use of in-feed additives such as antibiotics. In the past decades, the livestock feed industry had been centered on the use of antibiotics as livestock growth promoters. However, there has also been the negative development of microbial antibiotic resistance with various countries promulgating laws and regulations to ban and discourage in-feed antibiotic applications in the livestock feed industry. Thus, present and future improvements in livestock nutrition and feed resources are now being directed at the use of approved probiotics and the application of nanotechnology in livestock nutrition and feeding.

**Keywords:** improvements, livestock, nutrition, feeding, biotechnology

## **1. Introduction**

Nutrition could be a serious limitation to livestock production especially when feed resources are inadequate in both quality and quantity. Global livestock production over the years has increased consistently and brought about increases in animal numbers [1, 2]. However, these increases in the number of animals have not always been accompanied by an improved availability of livestock feed resources. These may result in overgrazing, erosion, reduced health,

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

and performance [2]. Feed quality and quantity combined with low producer prices have often forced farmers and feed producers to remain at low levels of animal feed production, compensated by large numbers of animals. It is evident that high global population growth, accompanied by high future projections of demand for livestock products, stresses the need for higher productivity per animal as well as increases in the number of animals. Inadequate feed quality and quantity impedes increased animal production. As the world population is expected to increase from 6 to about 8.3 billion in 2030 at an average growth rate of 1.1% per year, it is essential to be prepared to produce sufficient food for the increased population based on locally available feed resources especially in the developing countries [3]. These authors [3] also stated that there are opportunities and challenges for researchers to increase animal productivity in terms of quantity and quality, through the application of appropriate technologies in production systems, nutrition, and feeding of livestock. Feed is the most important input in all livestock production systems in terms of cost, and the availability of low priced, high-quality feeds is critical if livestock production is to remain competitive and continue to grow to meet demand for animal protein. A researcher [4] mentioned that conventional methods of livestock improvements (genetics and breeding, livestock nutrition and livestock disease management) have been used in the past and served the purpose of increasing livestock productivity. However, these options can no longer sustain higher production; consequently, new intensive techniques including biotechnology are now required to augment productivity. Modern biotechnology has the potential to provide new opportunities for achieving enhanced livestock productivity in a way that alleviates poverty, improve food security and nutrition, and promote sustainable use of natural resources.

**2. Nutrient requirements for livestock**

**2.1. Formulation of diets for poultry**

44.00 mg/kg zinc, and 0.13–0.19% sodium.

nonphytate phosphorus, and 150 mg/day sodium.

monogastrics.

• Laying chickens

• Broiler chickens

0.123–0.20% sodium. • Broiler breeders

• Turkey poults

• Turkeys 12–24 weeks old

• Turkey tom breeders

• Turkey hen breeders

sodium.

Nutrient requirement tables provide a summary of recommended minimum levels of nutrients for different livestock species. Livestock should be fed differently to meet body requirement based on their species, age, and purpose of production. The recommendations only serve as guidelines used for choosing dietary nutrient (energy, protein, essential amino acids, essential fatty acids, minerals, vitamins) concentrations in practical diets. Most nutrients are obtained from digestion of feedstuffs but few such as minerals, vitamins, and some essential amino acids are often supplied as synthetic supplements particularly in

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Poultry raised under intensive system should be fed balanced diet based on species, age, and purpose of production. The major classes of chickens are meat chickens (broilers) and laying hens (layers). **Table 1** provides a summary of recommended minimum levels of selected

Nutrient requirements for laying chickens consuming between 80 and 120 g/hen/day are as follows: 12.50–18.80% crude protein, 2.71–4.06% calcium, 0.21–0.31% nonphytate phosphorus, 0.13–0.19% mg/kg potassium, 29.00–

Broilers of ages between 0 and 8 weeks old require the ranges of nutrients as follows: 18–23% crude protein; 0.80–1.00% calcium; 0.30–0.45% nonphytate phosphorus; 0.30% potassium; 8.00 mg/kg copper; 40.00 mg/kg zinc;

Broiler breeders require the following nutrients ranges: 19.5 g/day crude protein, 4.0 g/day calcium, 350.0 mg/day

Turkey poults at 0–12 weeks old require the following ranges of nutrients: 22.0–28.0% crude protein, 0.85–1.20% calcium, 0.42–0.60% nonphytate phosphorus, 6.00–8.00 mg/kg copper, 50.00–70.00 mg/kg zinc, and 0.12–0.17%

Turkeys 12–24 weeks old require the following ranges of nutrients: 14.00–19.00% crude protein, 0.55–0.75% calcium,

Turkey tom breeders require the following ranges of nutrients: 12.00% crude protein, 0.50% calcium, 0.25%

Turkey hen breeders require the following ranges of nutrients: 14.00% crude protein, 0.25% calcium, 0.35%

**Table 1.** Summary of recommended minimum levels of some nutrients for different classes of poultry.

0.28–0.38% nonphytate phosphorus, 6.00 mg/kg copper, 40.00 mg/kg zinc, and 0.12% sodium.

nonphytate phosphorus, 6.00 mg/kg copper, 40.00 mg/kg zinc, and 0.12% sodium.

nonphytate phosphorus, 8.00 mg/kg copper, 65.00 mg/kg zinc, and 0.12% sodium.

Considerable improvement has occurred in livestock nutrition and feeding over the past two decades. Globally, livestock production is growing faster than any other sector, and by 2020, livestock is predicted to become the most important agricultural sector in terms of added value [5]. In a research conducted [6], it was also reported that the feeding of genetically engineered (GE) crops to livestock for the past 15 years has shown compositional equivalence and comparable levels of safety between GE crops and their conventional counterparts. Previous researchers [7] stated that recently production demands on the livestock industry have been centralized against the use of antibiotics as growth promoters due to growing concern over microbial antibiotic resistance. Thus, with many countries reporting increased incidences of antibiotic-resistant bacteria, laws and regulations are being updated to end in-feed antibiotic use in the animal production industry. This calls for suitable alternatives to be established for inclusion in livestock feed. Many reports have shown evidence that approved probiotics and nanoparticles may be better alternatives for animal growth promotion and antimicrobials. Researchers [7], however, explained that despite the expansion of antibiotic resistance in bacteria, antibiotics have not yet been rendered totally ineffective against them. And that the delivery and efficacy of antibiotics could, however, be enhanced by nanoparticle carriers, thereby potentially decreasing the dosage of antibiotics required for treatment.

Recent advances in livestock nutrition, especially in monogastrics, have focused on three main aspects: (i) developing the understanding of nutrient requirements of livestock, (ii) determining the supply and availability of nutrients in feed ingredients, and (iii) formulating least-cost diets that bring nutrient requirements and nutrient supply together efficiently.

## **2. Nutrient requirements for livestock**

Nutrient requirement tables provide a summary of recommended minimum levels of nutrients for different livestock species. Livestock should be fed differently to meet body requirement based on their species, age, and purpose of production. The recommendations only serve as guidelines used for choosing dietary nutrient (energy, protein, essential amino acids, essential fatty acids, minerals, vitamins) concentrations in practical diets. Most nutrients are obtained from digestion of feedstuffs but few such as minerals, vitamins, and some essential amino acids are often supplied as synthetic supplements particularly in monogastrics.

#### **2.1. Formulation of diets for poultry**

Poultry raised under intensive system should be fed balanced diet based on species, age, and purpose of production. The major classes of chickens are meat chickens (broilers) and laying hens (layers). **Table 1** provides a summary of recommended minimum levels of selected

and performance [2]. Feed quality and quantity combined with low producer prices have often forced farmers and feed producers to remain at low levels of animal feed production, compensated by large numbers of animals. It is evident that high global population growth, accompanied by high future projections of demand for livestock products, stresses the need for higher productivity per animal as well as increases in the number of animals. Inadequate feed quality and quantity impedes increased animal production. As the world population is expected to increase from 6 to about 8.3 billion in 2030 at an average growth rate of 1.1% per year, it is essential to be prepared to produce sufficient food for the increased population based on locally available feed resources especially in the developing countries [3]. These authors [3] also stated that there are opportunities and challenges for researchers to increase animal productivity in terms of quantity and quality, through the application of appropriate technologies in production systems, nutrition, and feeding of livestock. Feed is the most important input in all livestock production systems in terms of cost, and the availability of low priced, high-quality feeds is critical if livestock production is to remain competitive and continue to grow to meet demand for animal protein. A researcher [4] mentioned that conventional methods of livestock improvements (genetics and breeding, livestock nutrition and livestock disease management) have been used in the past and served the purpose of increasing livestock productivity. However, these options can no longer sustain higher production; consequently, new intensive techniques including biotechnology are now required to augment productivity. Modern biotechnology has the potential to provide new opportunities for achieving enhanced livestock productivity in a way that alleviates poverty, improve food

148 Animal Husbandry and Nutrition

security and nutrition, and promote sustainable use of natural resources.

thereby potentially decreasing the dosage of antibiotics required for treatment.

diets that bring nutrient requirements and nutrient supply together efficiently.

Recent advances in livestock nutrition, especially in monogastrics, have focused on three main aspects: (i) developing the understanding of nutrient requirements of livestock, (ii) determining the supply and availability of nutrients in feed ingredients, and (iii) formulating least-cost

Considerable improvement has occurred in livestock nutrition and feeding over the past two decades. Globally, livestock production is growing faster than any other sector, and by 2020, livestock is predicted to become the most important agricultural sector in terms of added value [5]. In a research conducted [6], it was also reported that the feeding of genetically engineered (GE) crops to livestock for the past 15 years has shown compositional equivalence and comparable levels of safety between GE crops and their conventional counterparts. Previous researchers [7] stated that recently production demands on the livestock industry have been centralized against the use of antibiotics as growth promoters due to growing concern over microbial antibiotic resistance. Thus, with many countries reporting increased incidences of antibiotic-resistant bacteria, laws and regulations are being updated to end in-feed antibiotic use in the animal production industry. This calls for suitable alternatives to be established for inclusion in livestock feed. Many reports have shown evidence that approved probiotics and nanoparticles may be better alternatives for animal growth promotion and antimicrobials. Researchers [7], however, explained that despite the expansion of antibiotic resistance in bacteria, antibiotics have not yet been rendered totally ineffective against them. And that the delivery and efficacy of antibiotics could, however, be enhanced by nanoparticle carriers, Nutrient requirements for laying chickens consuming between 80 and 120 g/hen/day are as follows: 12.50–18.80% crude protein, 2.71–4.06% calcium, 0.21–0.31% nonphytate phosphorus, 0.13–0.19% mg/kg potassium, 29.00– 44.00 mg/kg zinc, and 0.13–0.19% sodium.

• Broiler chickens

Broilers of ages between 0 and 8 weeks old require the ranges of nutrients as follows: 18–23% crude protein; 0.80–1.00% calcium; 0.30–0.45% nonphytate phosphorus; 0.30% potassium; 8.00 mg/kg copper; 40.00 mg/kg zinc; 0.123–0.20% sodium.

• Broiler breeders

Broiler breeders require the following nutrients ranges: 19.5 g/day crude protein, 4.0 g/day calcium, 350.0 mg/day nonphytate phosphorus, and 150 mg/day sodium.

• Turkey poults

Turkey poults at 0–12 weeks old require the following ranges of nutrients: 22.0–28.0% crude protein, 0.85–1.20% calcium, 0.42–0.60% nonphytate phosphorus, 6.00–8.00 mg/kg copper, 50.00–70.00 mg/kg zinc, and 0.12–0.17% sodium.

• Turkeys 12–24 weeks old

Turkeys 12–24 weeks old require the following ranges of nutrients: 14.00–19.00% crude protein, 0.55–0.75% calcium, 0.28–0.38% nonphytate phosphorus, 6.00 mg/kg copper, 40.00 mg/kg zinc, and 0.12% sodium.

• Turkey tom breeders

Turkey tom breeders require the following ranges of nutrients: 12.00% crude protein, 0.50% calcium, 0.25% nonphytate phosphorus, 6.00 mg/kg copper, 40.00 mg/kg zinc, and 0.12% sodium.

• Turkey hen breeders

Turkey hen breeders require the following ranges of nutrients: 14.00% crude protein, 0.25% calcium, 0.35% nonphytate phosphorus, 8.00 mg/kg copper, 65.00 mg/kg zinc, and 0.12% sodium.

**Table 1.** Summary of recommended minimum levels of some nutrients for different classes of poultry.

<sup>•</sup> Laying chickens

nutrients for layers, broilers, broiler breeders, turkey poults, turkey growers, turkey tom breeders, and turkey hen breeders. In poultry, particularly in chickens, since each specific genotype has its own requirements, most commercial feed formulations are carried out based on minimum requirements recommended by the breeding companies from which they were obtained.

**2.3. Formulation of diets for fish**

Fish farmers need to make use of well-balanced, less expensive feeds as well as good fish farming management practices in order to achieve profitable production [10]. Species-specific feed formulations, which address the nutritional requirements of the different life stages of fish, are required in fish farming. Also, each specific genotype has its own nutrient requirements that meet the requirement for the different life stages. The fish larvae production and nutrition are usually undertaken by specialist breeding companies. Most commercial fish diets or feeds are formulated based on minimum requirements recommended by the breeding

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**Life stage/size class Range of values of crude protein (CP%)**

Amino acids Requirement for all life stages (% aa)

Lipids Requirement for all life stages is 8–10% lipids

Carbohydrates (CHO) Requirement for all life stages is 12% CHO

Essential fatty acids (minimum %)

Arachidonic acid (20:4n-6) 0.5 Eicosapentaenoic acid (EPA) (20:5n-3) 1.0 Docosahexaenoic acid (22:6n-3) 0.5

Crude fiber, % max. 3.0 Gross energy, min. kJ/g 15.5

Fry 45–50 Fingerling 45 Juvenile 43 Grower 42 Broodstock 35–40

Arginine 2.0 Histidine 0.7 Isoleucine 0.8 Leucine 1.4 Lysine 1.8 Methionine 1.0 Phenyalanine 1.2 Threonine 0.8 Tryptophan 0.2 Valine 1.3

#### **2.2. Formulation of diets for pigs**

There are numerous feed ingredients that provide nutrients that pigs require for normal performance. Pigs do not require specific ingredients in their diets, but instead they require energy and nutrients such as amino acids, minerals, and vitamins. They should be fed diets that are balanced with respect to amino acids, containing adequate levels and ratios of the 10 essential amino acids required by pigs for maintenance, growth, reproduction, and lactation. The 10 essential amino acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. In a review article [8], it was explained that in pigs, amino acids are reported to be the chemical components of protein and are generally supplied to the pig from the crude protein in the diet. Failure to supplement low protein diet or feedstuff with sufficient amounts of good quality protein source was observed [8], which results in poor growth, insufficient feed utilization, increased carcass fatness, general unthriftiness, and or reduced reproductive performance. This researcher [8] also mentioned that in pigs, diet crude fiber should not exceed 10–15% of the diet as feed intake may be depressed. Growing and lactating pigs should be fed *ad libitum* while others could be limitedly fed. Presented in **Table 2** are some amino acid requirements in pigs.


nd, not determined; source: [9].

**Table 2.** Amino acid (%) requirements for pigs.

#### **2.3. Formulation of diets for fish**

nutrients for layers, broilers, broiler breeders, turkey poults, turkey growers, turkey tom breeders, and turkey hen breeders. In poultry, particularly in chickens, since each specific genotype has its own requirements, most commercial feed formulations are carried out based on minimum requirements recommended by the breeding companies from which

There are numerous feed ingredients that provide nutrients that pigs require for normal performance. Pigs do not require specific ingredients in their diets, but instead they require energy and nutrients such as amino acids, minerals, and vitamins. They should be fed diets that are balanced with respect to amino acids, containing adequate levels and ratios of the 10 essential amino acids required by pigs for maintenance, growth, reproduction, and lactation. The 10 essential amino acids are arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. In a review article [8], it was explained that in pigs, amino acids are reported to be the chemical components of protein and are generally supplied to the pig from the crude protein in the diet. Failure to supplement low protein diet or feedstuff with sufficient amounts of good quality protein source was observed [8], which results in poor growth, insufficient feed utilization, increased carcass fatness, general unthriftiness, and or reduced reproductive performance. This researcher [8] also mentioned that in pigs, diet crude fiber should not exceed 10–15% of the diet as feed intake may be depressed. Growing and lactating pigs should be fed *ad libitum* while others could be limitedly fed. Presented in **Table 2** are some amino acid

**Amino acid Growers Pregnancy Lactation** Arginine nd 0.15 0.41 Histidine nd nd 0.37 Isoleucine nd 0.42 0.46 Lysine 1.10 0.43 0.55 Methionine 0.26 0.12 0.30–0.36 Methionine/cystine 0.57 0.06 nd Phenylalanine nd nd nd Threonine 0.60–0.70 0.41 0.42 Tryptophan 0.18–0.20 nd 0.12 Valine nd 0.32 0.53–0.68

they were obtained.

150 Animal Husbandry and Nutrition

requirements in pigs.

nd, not determined; source: [9].

**Table 2.** Amino acid (%) requirements for pigs.

**2.2. Formulation of diets for pigs**

Fish farmers need to make use of well-balanced, less expensive feeds as well as good fish farming management practices in order to achieve profitable production [10]. Species-specific feed formulations, which address the nutritional requirements of the different life stages of fish, are required in fish farming. Also, each specific genotype has its own nutrient requirements that meet the requirement for the different life stages. The fish larvae production and nutrition are usually undertaken by specialist breeding companies. Most commercial fish diets or feeds are formulated based on minimum requirements recommended by the breeding



companies that supply the fry or fingerlings. Fish require nutrients such as crude protein, essential amino acids, essential fatty acids, lipids, carbohydrates, crude fiber, minerals, and vitamins [11]. **Table 3** presents the summary of dietary nutrient requirements and utilization

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Some of the ingredients required in early fry to brooder stages are as follows: fish meal of between 30 and 68%, corn meal of 0–4%, poultry by-product meal of 2–8%, ground wheat of 17–22%, fish oil of 9–12%, vitamin premix of 1.5%, and mineral premix of 0.5%. Sources:

Some of the feed parameters and proximate composition requirements between early fry and brooder stages are as follows: 3–8% of body weight, 6 months maximum shelf life of feed, addition of probiotics to improve the feed conversion efficiency, 2–5 mm pellet size (mash for early fry), 35–48% crude protein, 8–21% crude lipid, 9–12% ash, less than 3–6% crude fiber,

Ruminants have distinct advantage over monogastrics in being able to convert organic materials that are not suitable for human consumption into products that are of high nutritional value such as meat, milk, and by-products [13–15]. They also provide fertilizer from the faecal and undigested residues. The aim in the feeding of ruminants thus should be to feed as much forage as possible that could satisfy most of the nutrient requirements of the animal. The quantity and quality of roughage made available to the ruminant will then determine the

In young stock, the rumen will not be developed and it will take a few months until the rumen is fully developed and starts functioning. Until then, the young ruminant is similar to a simple-stomached animal nutritionally. In young stock, essential amino acids should be provided in required quantity in the ration. The B-complex vitamins, vitamins A and D, and minerals should be provided usually from the milk. Colostrum should be given at days 1–3 after birth as antibodies (gamma globulins) are transferred from the dam to

Ruminants have a forestomach composed of fermentation compartments, which contain large amounts of microorganisms (bacteria, protozoa, fungi). These break down the cellulose in fibrous plant material into a form that can be digested in the animal's stomach and intestines. There is a symbiosis between ruminants and microorganisms, as the microorganisms need

of rainbow trout (*Oncorhynchus mykiss*) (fish) at different life stages or size classes.

*2.3.2. Feed parameters and proximate composition for different life stages of fish*

12–13% nitrogen-free extract, and 17–21 kJ/g gross energy. Sources: [10, 11].

*2.3.1. Ingredient composition for different life stages of fish*

**2.4. The feeding of ruminants: cattle, sheep, and goats**

amount and type of supplement or concentrate to be fed.

*2.4.1. Feeding of young ruminants*

*2.4.2. Feeding of adult ruminants*

its young.

[10, 11].

Requirements were measured in fingerling and juvenile fish. Values for other life-history stages are estimates. Data source: [12].

**Table 3.** Dietary nutrient requirements of rainbow trout (*Oncorhynchus mykiss*) (requirements are expressed for dry feed).

companies that supply the fry or fingerlings. Fish require nutrients such as crude protein, essential amino acids, essential fatty acids, lipids, carbohydrates, crude fiber, minerals, and vitamins [11]. **Table 3** presents the summary of dietary nutrient requirements and utilization of rainbow trout (*Oncorhynchus mykiss*) (fish) at different life stages or size classes.

#### *2.3.1. Ingredient composition for different life stages of fish*

**Life stage/size class Range of values of crude protein (CP%)**

Minerals Requirement for all life stages

Vitamins min. (IU/kg) Requirement for all life stages

Vitamins, min. (mg/kg) Requirement for all life stages

Requirements were measured in fingerling and juvenile fish. Values for other life-history stages are estimates. Data

**Table 3.** Dietary nutrient requirements of rainbow trout (*Oncorhynchus mykiss*) (requirements are expressed for

Digestible energy, min. kJ/g 15.5 Protein:energy ratio, mg/kJ 25.0

Calcium, max. 1.0 Phosphorus, min. 0.8 Magnesium, min. 0.05 Sodium, min. 0.06

Potassium 0.7 Iron 60.0 Copper 3.0 Manganese 13.0 Zinc 30.0 Selenium 0.3 Iodine 1.1

Vitamin A 2500 Vitamin D 2000–2400

Vitamin E 25–100 Vitamin K 1.0 Thiamine 10.0 Riboflavin 5.0 Pyridoxine 6.0 Pantothenic acid 20.0 Niacin 10.0 Folic acid 2.0 Vitamin B 12 0.02 Choline 800.0 Inositol 300.0 Biotin 0.15 Ascorbic acid 40.0

Macroelements (%)

152 Animal Husbandry and Nutrition

source: [12].

dry feed).

Microelements, min. (mg/kg)

Some of the ingredients required in early fry to brooder stages are as follows: fish meal of between 30 and 68%, corn meal of 0–4%, poultry by-product meal of 2–8%, ground wheat of 17–22%, fish oil of 9–12%, vitamin premix of 1.5%, and mineral premix of 0.5%. Sources: [10, 11].

#### *2.3.2. Feed parameters and proximate composition for different life stages of fish*

Some of the feed parameters and proximate composition requirements between early fry and brooder stages are as follows: 3–8% of body weight, 6 months maximum shelf life of feed, addition of probiotics to improve the feed conversion efficiency, 2–5 mm pellet size (mash for early fry), 35–48% crude protein, 8–21% crude lipid, 9–12% ash, less than 3–6% crude fiber, 12–13% nitrogen-free extract, and 17–21 kJ/g gross energy. Sources: [10, 11].

#### **2.4. The feeding of ruminants: cattle, sheep, and goats**

Ruminants have distinct advantage over monogastrics in being able to convert organic materials that are not suitable for human consumption into products that are of high nutritional value such as meat, milk, and by-products [13–15]. They also provide fertilizer from the faecal and undigested residues. The aim in the feeding of ruminants thus should be to feed as much forage as possible that could satisfy most of the nutrient requirements of the animal. The quantity and quality of roughage made available to the ruminant will then determine the amount and type of supplement or concentrate to be fed.

#### *2.4.1. Feeding of young ruminants*

In young stock, the rumen will not be developed and it will take a few months until the rumen is fully developed and starts functioning. Until then, the young ruminant is similar to a simple-stomached animal nutritionally. In young stock, essential amino acids should be provided in required quantity in the ration. The B-complex vitamins, vitamins A and D, and minerals should be provided usually from the milk. Colostrum should be given at days 1–3 after birth as antibodies (gamma globulins) are transferred from the dam to its young.

#### *2.4.2. Feeding of adult ruminants*

Ruminants have a forestomach composed of fermentation compartments, which contain large amounts of microorganisms (bacteria, protozoa, fungi). These break down the cellulose in fibrous plant material into a form that can be digested in the animal's stomach and intestines. There is a symbiosis between ruminants and microorganisms, as the microorganisms need the energy and nutrients in forage for their own nutrition, and the microorganisms are finally broken down as protein source for the host ruminant. Thus, ruminants need lesser grains and concentrate diets than monogastrics such as pigs and poultry, which do not have a forestomach full of microorganisms, which act as protein source.

the digestible energy from fibrous carbohydrates is converted to volatile fatty acids (VFA) within the rumen. The conversion of carbohydrates to VFA is dependent on the microbes present in the ruminant digestive tract. The level of 8% crude protein of diets is required to provide the minimum ammonia levels required by microorganisms for optimum rumen

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Tables of values of nutrients (CP, fat, minerals, vitamins, etc.) required by ruminants are never given because these values are calculated based on how rapidly the nutrients degrade in the rumen (rate of digestion) and how rapidly the feed passes through the rumen i.e., rate of passage [17]. The rate of digestion is related to the properties of the feed, while rate of passage increases with increasing dry matter intake (DMI), body weight of animal, etc. These values are usually not constant; however, effort is being made to calculate more approximate values. The protein requirement of ruminants can be divided into two groups: rumen degradable protein (RDP) or by pass proteins, which is degraded in the rumen by the rumen microbes e.g., groundnut cake, fish meal, soybean meal, rape seed cake, etc. [18]. These degraded proteins are then broken down into amino acids and urea. However, rapid fermentation of proteins in the rumen results largely to feed wastage (except in high milk production), since most of the ammonia by-products liberated are excreted as urea through urine. Rumen undegradable proteins (RUP) are not easily degraded by rumen microbes e.g., nonprotein nitrogen (NPN) compounds such as urea, uric acid, biuret (usually present in fermented forages) and other treated nitrogen sources, which normally escape the rumen fermentation. Shown in **Table 4** are some nutrient supply input requirements and the limits of neutral detergent fiber (NDF)

Livestock nutrition can be categorized into diets for nonruminants (monogastrics) and ruminants. Most nonruminants are omnivorous, having simple digestive system commonly with nonfunctional caecum. However, the digestive system in ruminants has the four roughage

Energy sources normally constitute the highest proportion (about 50–60%) of livestock diets, followed by plant protein sources (about (10–20%), next is the fiber and animal protein sources (10–15%), and the lowest rates of inclusions usually occur in the minerals and additives as feed ingredients. Globally, maize (corn) is the most commonly used energy source, and soybean meal or cake is a common plant protein source, while fishmeal is the major animal protein

**3.1. Commonly used conventional and alternative feedstuffs and/or agroindustrial** 

and nonfibrous carbohydrates (NFC) requirements in ruminant diets.

diet digestion chambers, rumen, reticulum, omasum, and abomasum.

**3. Livestock feed availability and nutrition**

activity [16].

**by-products**

*2.4.3.1. Formulation of diet in ruminants*

#### *2.4.3. Ruminant nutrition*

In ruminant nutrition, one must know the amount of energy required by an animal for a specific production function, if it is desired to obtain the most efficient utilization of a feedstuff. During food metabolism, energy in the diet is broken down from gross energy into net energy for maintenance and for production. To meet the energy requirements in ruminants, the energy value of feeds is most important but one also needs to have a balance of other nutrients such as proteins, amino acids, fats, minerals, and vitamins as shown in **Table 4**. The deficiency in any one of the nutrients may impair metabolism. To minimize the possibilities of nutritional deficiencies, various feeding systems have been formulated to assist nutritionists in selecting ration components. These systems involve (i) practical application of the basic concepts of energy systems, (ii) metabolic processes whereby energy is released from specific nutrients, and (iii) the roles played by volatile fatty acids in ruminant nutrition. It is important to know that in general, as the fiber level of ruminant rations decreases, the concentration of acetic acid in the rumen contents also decreases. The fiber fraction of feeds are usually broken down into acetic, propionic, and butyric acids, and about 60% of


**Table 4.** Some nutrient supply input requirements and the limits of neutral detergent fiber (NDF) and nonfibrous carbohydrate (NFC) requirements in ruminant diets (%).

the digestible energy from fibrous carbohydrates is converted to volatile fatty acids (VFA) within the rumen. The conversion of carbohydrates to VFA is dependent on the microbes present in the ruminant digestive tract. The level of 8% crude protein of diets is required to provide the minimum ammonia levels required by microorganisms for optimum rumen activity [16].

#### *2.4.3.1. Formulation of diet in ruminants*

the energy and nutrients in forage for their own nutrition, and the microorganisms are finally broken down as protein source for the host ruminant. Thus, ruminants need lesser grains and concentrate diets than monogastrics such as pigs and poultry, which do not have a forestomach

In ruminant nutrition, one must know the amount of energy required by an animal for a specific production function, if it is desired to obtain the most efficient utilization of a feedstuff. During food metabolism, energy in the diet is broken down from gross energy into net energy for maintenance and for production. To meet the energy requirements in ruminants, the energy value of feeds is most important but one also needs to have a balance of other nutrients such as proteins, amino acids, fats, minerals, and vitamins as shown in **Table 4**. The deficiency in any one of the nutrients may impair metabolism. To minimize the possibilities of nutritional deficiencies, various feeding systems have been formulated to assist nutritionists in selecting ration components. These systems involve (i) practical application of the basic concepts of energy systems, (ii) metabolic processes whereby energy is released from specific nutrients, and (iii) the roles played by volatile fatty acids in ruminant nutrition. It is important to know that in general, as the fiber level of ruminant rations decreases, the concentration of acetic acid in the rumen contents also decreases. The fiber fraction of feeds are usually broken down into acetic, propionic, and butyric acids, and about 60% of

full of microorganisms, which act as protein source.

• Dry matter • Fat

• Lignin • Vitamins: A, D, E

• Processing factor (e.g., drying, ensiling, pellets production, urea treatment, multi-nutrients-blocks

• Neutral detergent fiber (NDF): 15–19% of DM of minimum forage NDF, 25–33% of DM of minimum

• Nonfibrous carbohydrates (NFC): 36–44% of DM of

• Crude protein—rumen degradable protein (RDP),

carbohydrate (NFC) requirements in ruminant diets (%).

in diets

rumen undegradable protein (RUP)

production, etc.)

NDF in diets • Acid detergent fiber

maximum NFC\*

Starch as source of NFC.

\*

Source: [17].

• Feed category/class (e.g., forages, concentrates, etc.) • Major minerals: Ca, P, K, Mg, Cl, Na

• Minor minerals: S, Co, Cu, I, Fe, Mn, Se, Zn

tryptophan, valine

• Feed additives

**Table 4.** Some nutrient supply input requirements and the limits of neutral detergent fiber (NDF) and nonfibrous

• Amino acids: methionine, lysine, arginine, histidine, isoleucine, leucine, cystine, phenylalanine, threonine,

• Digestibility coefficients of: CP, NDF, fat, NFC

*2.4.3. Ruminant nutrition*

154 Animal Husbandry and Nutrition

Tables of values of nutrients (CP, fat, minerals, vitamins, etc.) required by ruminants are never given because these values are calculated based on how rapidly the nutrients degrade in the rumen (rate of digestion) and how rapidly the feed passes through the rumen i.e., rate of passage [17]. The rate of digestion is related to the properties of the feed, while rate of passage increases with increasing dry matter intake (DMI), body weight of animal, etc. These values are usually not constant; however, effort is being made to calculate more approximate values. The protein requirement of ruminants can be divided into two groups: rumen degradable protein (RDP) or by pass proteins, which is degraded in the rumen by the rumen microbes e.g., groundnut cake, fish meal, soybean meal, rape seed cake, etc. [18]. These degraded proteins are then broken down into amino acids and urea. However, rapid fermentation of proteins in the rumen results largely to feed wastage (except in high milk production), since most of the ammonia by-products liberated are excreted as urea through urine. Rumen undegradable proteins (RUP) are not easily degraded by rumen microbes e.g., nonprotein nitrogen (NPN) compounds such as urea, uric acid, biuret (usually present in fermented forages) and other treated nitrogen sources, which normally escape the rumen fermentation. Shown in **Table 4** are some nutrient supply input requirements and the limits of neutral detergent fiber (NDF) and nonfibrous carbohydrates (NFC) requirements in ruminant diets.

## **3. Livestock feed availability and nutrition**

Livestock nutrition can be categorized into diets for nonruminants (monogastrics) and ruminants. Most nonruminants are omnivorous, having simple digestive system commonly with nonfunctional caecum. However, the digestive system in ruminants has the four roughage diet digestion chambers, rumen, reticulum, omasum, and abomasum.

#### **3.1. Commonly used conventional and alternative feedstuffs and/or agroindustrial by-products**

Energy sources normally constitute the highest proportion (about 50–60%) of livestock diets, followed by plant protein sources (about (10–20%), next is the fiber and animal protein sources (10–15%), and the lowest rates of inclusions usually occur in the minerals and additives as feed ingredients. Globally, maize (corn) is the most commonly used energy source, and soybean meal or cake is a common plant protein source, while fishmeal is the major animal protein ingredient used in livestock rations. These three feed ingredients are known to be the conventional livestock feed ingredients, and they usually constitute a part of livestock concentrate feeds. They have been facing market competition with human food demands, especially in the developing countries, and this trend has been tagged as "feed-food competition" [19]. To cope


with the feed-food competition, it has been necessary to explore the use of locally available, cheaper alternative feedstuffs for use in livestock feed formulations. A wide range of alternative feedstuffs are being used in livestock feeding globally, and these could be categorized into alternative energy, fiber, plant protein, animal protein sources, and feed additives as shown in **Table 5**. **Table 6** presents the proximate analysis of some commonly used livestock

**Ingredients (%) DM CP EE CF NFE Ash Source** Groundnut cake 90.0 45.3 11.0 5.0 27.5 1.2 [20] Palm kernel cake 94.0 14–21 5–17 13–23 48.0 3–12 [23, 24] Cotton seed cake 86–93 26–36 6.7 7.1 44.5 5.8 [10, 20] Fish meal 95.0 35.0 8.6 17.6 45.0 9.1 [20] Blood meal 89.5 76–80 1.2 1.5 47.1 1.3 [20] Poultry manure 92.6 16.8 2.5 10.0 50.2 13.1 [25, 26] Snail 86–91 65–67 7.9 3.06 17.2 7.8 [27] House fly larva nd 60.0 20.0 nd nd nd [26, 28] Leaf-meal (duck weed) 92.3 24.8 5.7 12.1 54.5 2.0 [20]

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The aim in formulating least cost rations, particularly on large commercial farms, is to undertake a precision feeding in order to lower cost and to maximize economic efficiency. In the past, there was a great tendency to over formulate diets when the exact requirements, especially for critical nutrients such as amino acids and phosphorus for monogastrics, were uncertain. This practice is currently known to be wasteful and also lead to the excretion of excess nutrients in manure, ultimately serving as source of environmental

After defining the nutritional needs of a group of livestock, next step would be to match these needs with the use of combination of ingredients and supplements to arrive in a balanced diet that provides appropriate quantities of biologically available nutrients, particularly for nonruminants. Thus, given the range of possible feedstuffs' proximate composition (as shown in **Table 6**), and the targeted dietary nutrient levels expected, a lot of calculations are then carried out to arrive at least-cost diets. However, over the years, feed formulation has evolved from a simple balancing of a few feedstuffs for a limited number of nutrients to a linear pro-

gramming system that operates with the use of computers [29].

feed ingredients.

nd, not determined.

pollution [29].

**4. Formulation of least cost rations**

**Table 6.** Proximate analysis of some commonly used livestock feed ingredients.

\* Serves as both conventional and alternative feedstuff.

**Table 5.** Conventional and the alternative feedstuffs commonly used in nonruminant and ruminant concentrate diet formulations.



**Table 6.** Proximate analysis of some commonly used livestock feed ingredients.

with the feed-food competition, it has been necessary to explore the use of locally available, cheaper alternative feedstuffs for use in livestock feed formulations. A wide range of alternative feedstuffs are being used in livestock feeding globally, and these could be categorized into alternative energy, fiber, plant protein, animal protein sources, and feed additives as shown in **Table 5**. **Table 6** presents the proximate analysis of some commonly used livestock feed ingredients.

## **4. Formulation of least cost rations**

ingredient used in livestock rations. These three feed ingredients are known to be the conventional livestock feed ingredients, and they usually constitute a part of livestock concentrate feeds. They have been facing market competition with human food demands, especially in the developing countries, and this trend has been tagged as "feed-food competition" [19]. To cope

**Conventional feedstuffs Alternative feedstuffs Range of inclusion** 

meal or peel meal, palm oil slurry, sesame seed meal, forage plants

Palm kernel cake, cotton seed cake, pigeon pea meal, cowpea vines, groundnut haulms, soybean haulms, potato vines

Blood meal, poultry offal meal, hydrolyzed feather meal, dried poultry manure meal, snail meat meal, insect fly, pupal and larval

**Table 5.** Conventional and the alternative feedstuffs commonly used in nonruminant and ruminant concentrate diet

**Ingredients (%) DM CP EE CF NFE Ash Source** Wheat bran 88.0 14–19 6.5 10.6–16.0 59.5 4.0 [10, 20] Maize bran 93.0 10–15 4.4 11.6 70.8 3.2 [10] Rice bran 91.0 12–13 2.4–3.4 12.3 63.0 0.9 [20] Maize 87.0 9.9 4.4 2–3 70.0 4.5 [21] Cassava root meal 88.3 1.5–3.5 3.4 3.7 91.0 1.1 [20] Cassava peel meal 33.5 6.5 1.3 16.6 68.5 5.9 [22]

Maize, vegetable oils Sorghum, cassava root meal or peel meal, yam peels, potato root

Wheat bran, maize bran Rice bran/husk, maize husk 10–15

meals, earthworms, crystalline amino acid sources

Oyster shells Periwinkle shells 2–5 Bone meal Limestone 2–3 Dicalcium phosphate Malt dust 1–2

Vitamin premix 1 Common salt 0.25–0.50

Energy source

156 Animal Husbandry and Nutrition

Fiber sources

Plant protein sources Soybean meal, groundnut cake, Palm kernel cake

Animal protein sources Fish meal, blood meal \*

Mineral sources

Feed additives

Others (probiotics, prebiotics

formulations.

\*

\*

Serves as both conventional and alternative feedstuff.

**rates (% of DM)**

50–60

10–20

5–10

0.25–0.50

The aim in formulating least cost rations, particularly on large commercial farms, is to undertake a precision feeding in order to lower cost and to maximize economic efficiency. In the past, there was a great tendency to over formulate diets when the exact requirements, especially for critical nutrients such as amino acids and phosphorus for monogastrics, were uncertain. This practice is currently known to be wasteful and also lead to the excretion of excess nutrients in manure, ultimately serving as source of environmental pollution [29].

After defining the nutritional needs of a group of livestock, next step would be to match these needs with the use of combination of ingredients and supplements to arrive in a balanced diet that provides appropriate quantities of biologically available nutrients, particularly for nonruminants. Thus, given the range of possible feedstuffs' proximate composition (as shown in **Table 6**), and the targeted dietary nutrient levels expected, a lot of calculations are then carried out to arrive at least-cost diets. However, over the years, feed formulation has evolved from a simple balancing of a few feedstuffs for a limited number of nutrients to a linear programming system that operates with the use of computers [29].


when transgenic forage crops are first fed to ruminants, then the animal products to be consumed by humans from these ruminants are not themselves transgenic. This implies that food products derived from animals fed with transgenic forage crops are safer than when directly modified crops are consumed by humans. Also, in another research [30], it was demonstrated that the inclusion of genetically modified corn silage in dairy cows diets did not affect feed intake or milk production. The corn silage diet fed to the dairy cows was engineered with substantial improvements in their nutrient (proteins, amino acids, oils, fatty acids, starches, sugars, fiber, vitamins, minerals, enzymes) contents. The feed intake or milk production was not negatively affected, and there was absence of transgenic DNA in the milk harvested from these experimental cows. Thus, designer ingredients or plants (e.g., high oil maize) with genetic modification are made to enhance nutrition. There could also be designer ingredients (e.g., low-phytate maize) or forage crops engineered to reduce the level of antinutritive compounds, which occur in livestock feed ingredients. A researcher [5] reported that feeds derived from genetically modified (GM) plants (a quarter of which are now grown in developing countries), such as grain, silage, and hay, have contributed to an increase in livestock growth rates and milk yield. Also, genetically modified crops with improved amino acid profiles can be used to decrease nitrogen excretion in pigs and poultry. The author [5] explained that increasing the levels of amino acids in grains means that the essential amino acid require-

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ments of pigs and poultry can be met by diets that are lower in protein content.

to be more homogenous and of better quality.

Other biotechnological applications of different classes of feed additives outlined in **Table 7** are the use of crystalline amino acids, antioxidants, antifungals, antibiotics, and different classes of antibiotic replacers. Feed additives may be added to the diet to enhance the effectiveness of nutrients, and they also exert their effects in the gut or on the gut cell walls of the animal [31]. They are used for the purpose of promoting animal growth through their effect in increasing feed quality and palatability. Besides, they are mixed with the feed in nontherapeutic quantities and thus protecting the animal against all sorts of harmful environmental stresses. Low levels of additives in animal feed may contribute to increased production of animal protein for human consumption and thereby decrease the cost of animal product. The use of avoparcin, zinc bacitracin, spiramycin, virginiamycin, and tylosin phosphate as animal feed additives was banned in the European Union in 1998 and in 2006 [29]. The US, starting January, 2017, also enforced a ban on the use of antimicrobials (antibiotics and antifungals) to promote food animal growth [32]. Envisaging a total ban on in-feed antibiotic use, a multitude of compounds (individually and in combinations) are being tested to serve as alternatives [29]. Probiotics are defined as feed supplements that are added to the diet of farm animals to improve intestinal microbial balance [33]. Thus, in contrast to the use of antibiotics as nutritional modifiers, which destroy bacteria, the inclusion of probiotics in feeds is designed to encourage certain strains of bacteria in the gut at the expense of less desirable gut microorganisms [4]. This researcher [4] also mentioned that probiotics could produce vitamins of the B complex and digestive enzymes, and the stimulation of intestinal mucosa immunity, by increasing protection against toxins produced by pathogenic microorganisms. Thus in ruminants, probiotics are effective in controlling the diseases of the gastrointestinal tract of young animals. It was found that in adult ruminants, yeasts could be used as probiotics to improve rumen fermentation [33]. The use of these feed additives may help to make animal products

NB: The use of avoparcin, zinc bacitracin, spiramycin, virginiamycin, and tylosin phosphate as animal feed additives was banned in the European Union in 1998 and in 2006. The US, starting January, 2017, enforced a ban on the use of antimicrobials (antibiotics and antifungals) to promote food animal growth. Sources: [29, 32].

**Table 7.** Biotechnological and allied applications that are employed in livestock nutrition.

## **5. Some biotechnological and allied applications employed in livestock nutrition**

Modern biotechnology has the potential to provide new methods for achieving enhanced livestock productivity in ways that could alleviate poverty, promote food security and nutrition, and also promote sustainable use of natural resources [4]. The applications of biotechnology in animal nutrition were reported [29] and are as summarized in **Table 7**. The author mentioned that there could be the formation of new ingredients such as single-cell protein and yeast protein, and the aim is to manufacture microbial proteins as new feed sources for animal feeding. These could also be included in the ration of livestock in order to upgrade the crude protein content of the ration.

Secondly, as outlined in **Table 7**, there could be the application of designer ingredients that could be applied in designing genetically engineered plants and forage crops, which are genetically modified using recombinant DNA technology with the objective of introducing or enhancing a desirable characteristic in the plant or seed used. This author [4] explained that transgenic forage crops are aimed at bringing about some benefits to consumers. Thus, when transgenic forage crops are first fed to ruminants, then the animal products to be consumed by humans from these ruminants are not themselves transgenic. This implies that food products derived from animals fed with transgenic forage crops are safer than when directly modified crops are consumed by humans. Also, in another research [30], it was demonstrated that the inclusion of genetically modified corn silage in dairy cows diets did not affect feed intake or milk production. The corn silage diet fed to the dairy cows was engineered with substantial improvements in their nutrient (proteins, amino acids, oils, fatty acids, starches, sugars, fiber, vitamins, minerals, enzymes) contents. The feed intake or milk production was not negatively affected, and there was absence of transgenic DNA in the milk harvested from these experimental cows. Thus, designer ingredients or plants (e.g., high oil maize) with genetic modification are made to enhance nutrition. There could also be designer ingredients (e.g., low-phytate maize) or forage crops engineered to reduce the level of antinutritive compounds, which occur in livestock feed ingredients. A researcher [5] reported that feeds derived from genetically modified (GM) plants (a quarter of which are now grown in developing countries), such as grain, silage, and hay, have contributed to an increase in livestock growth rates and milk yield. Also, genetically modified crops with improved amino acid profiles can be used to decrease nitrogen excretion in pigs and poultry. The author [5] explained that increasing the levels of amino acids in grains means that the essential amino acid requirements of pigs and poultry can be met by diets that are lower in protein content.

Other biotechnological applications of different classes of feed additives outlined in **Table 7** are the use of crystalline amino acids, antioxidants, antifungals, antibiotics, and different classes of antibiotic replacers. Feed additives may be added to the diet to enhance the effectiveness of nutrients, and they also exert their effects in the gut or on the gut cell walls of the animal [31]. They are used for the purpose of promoting animal growth through their effect in increasing feed quality and palatability. Besides, they are mixed with the feed in nontherapeutic quantities and thus protecting the animal against all sorts of harmful environmental stresses. Low levels of additives in animal feed may contribute to increased production of animal protein for human consumption and thereby decrease the cost of animal product. The use of avoparcin, zinc bacitracin, spiramycin, virginiamycin, and tylosin phosphate as animal feed additives was banned in the European Union in 1998 and in 2006 [29]. The US, starting January, 2017, also enforced a ban on the use of antimicrobials (antibiotics and antifungals) to promote food animal growth [32]. Envisaging a total ban on in-feed antibiotic use, a multitude of compounds (individually and in combinations) are being tested to serve as alternatives [29].

**5. Some biotechnological and allied applications employed in** 

antimicrobials (antibiotics and antifungals) to promote food animal growth. Sources: [29, 32].

**Table 7.** Biotechnological and allied applications that are employed in livestock nutrition.

(ii) Prebiotics Oligosaccharides Renders harmful bacteria inactive

**Application Examples Functions**

Methionine, lysine, threonine,

bacitracin, avoparcin, tylosin,

butylated hydroxyl anisole (BHA),

(c) Antifungals Aflatoxin To control mold (e.g., *Aspergillus flavus*, *A.* 

(i) Probiotics In-feed microbials Source of beneficial microbial species such as

NB: The use of avoparcin, zinc bacitracin, spiramycin, virginiamycin, and tylosin phosphate as animal feed additives was banned in the European Union in 1998 and in 2006. The US, starting January, 2017, enforced a ban on the use of

To serve as new feed sources in the form of microbial proteins for livestock feeding

Play vital role in improving protein utilization

To prevent auto-oxidation of fats and oils in the

*parasiticus*) growth in feed, to bind and reduce

To control gram-positive, harmful bacterial species in the gut, improve production efficiency, used as a prophylactic measure

*Lactobacilli* species and *Streptococci* species

the negative effects of mycotoxins

against necrotic enteritis

other feedstuffs. Enhance nutrition

Low phytate maize, high-oil maize Reduce the levels of antinutrients in forages and

diet

(yeast protein)

tryptophan

ethoxyquin

spiramycin

(b) Antioxidants Butylated hydroxy toluene (BHT),

(d) Antibiotics Avilamycin, virginiamycin, zinc

1. Microbial proteins Single-cell protein, multicellular

2. Genetically engineered forage crops

158 Animal Husbandry and Nutrition

3. Feed additives (a) Crystalline amino acids

Modern biotechnology has the potential to provide new methods for achieving enhanced livestock productivity in ways that could alleviate poverty, promote food security and nutrition, and also promote sustainable use of natural resources [4]. The applications of biotechnology in animal nutrition were reported [29] and are as summarized in **Table 7**. The author mentioned that there could be the formation of new ingredients such as single-cell protein and yeast protein, and the aim is to manufacture microbial proteins as new feed sources for animal feeding. These could also be included in the ration of livestock in order to upgrade the

Secondly, as outlined in **Table 7**, there could be the application of designer ingredients that could be applied in designing genetically engineered plants and forage crops, which are genetically modified using recombinant DNA technology with the objective of introducing or enhancing a desirable characteristic in the plant or seed used. This author [4] explained that transgenic forage crops are aimed at bringing about some benefits to consumers. Thus,

**livestock nutrition**

(e) Antibiotic replacers

crude protein content of the ration.

Probiotics are defined as feed supplements that are added to the diet of farm animals to improve intestinal microbial balance [33]. Thus, in contrast to the use of antibiotics as nutritional modifiers, which destroy bacteria, the inclusion of probiotics in feeds is designed to encourage certain strains of bacteria in the gut at the expense of less desirable gut microorganisms [4]. This researcher [4] also mentioned that probiotics could produce vitamins of the B complex and digestive enzymes, and the stimulation of intestinal mucosa immunity, by increasing protection against toxins produced by pathogenic microorganisms. Thus in ruminants, probiotics are effective in controlling the diseases of the gastrointestinal tract of young animals. It was found that in adult ruminants, yeasts could be used as probiotics to improve rumen fermentation [33]. The use of these feed additives may help to make animal products to be more homogenous and of better quality.

## **6. Practical application of biotechnology in monogastrics (poultry, pigs, and fish) and ruminants (cattle, sheep, and goats)**

Biotechnology is offering a lot of opportunities for increasing agricultural productivity and for protecting the environment through the reduced use of agrochemicals [34]. Techniques of modern biology such as genetic manipulation of rumen microbes, and chemical and biological treatment of low-quality animal feeds for improved nutritive value among others have become a reality in the past few decades and are finding their ways into present research and development programs. These go along side with fleeting coverage of issues concerning the potential environmental hazards of genetic engineering and other biotechnologies, and the need for their ethical evaluation and for an international regulatory mechanism [34]. Practical application of biotechnology in monogastrics (poultry, pigs, and fish) and in ruminants (cattle, sheep, and goats) is hereby discussed below.

extract up to 25% of energy maintenance requirements from fermentation products. Also, dietary fiber improves pig intestinal health by promoting the growth of lactic acid bacteria,

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In another journal article [37], it was reported that in growing pigs, the effects of four dietary levels of microbial phytase (Natuphos) enzyme on the apparent and true digestibility of Ca, P, CP, and AA in dehulled soybean meal were assessed. In the study, the researchers observed that supplemental microbial phytase did not improve the utilization of amino acid provided by soybean meal but was an effective means of improving calcium and phosphorus utiliza-

It was observed that in pigs, feeding recombinant DNA produced crops and newly expressed proteins in genetically modified (GM) plants showed no biologically relevant effects on feed intake, digestibility, or animal health [35]. Also, there were no unintended effects on the performance and fertility of animals. The food products obtained from the pigs fed with GM

In a journal review article [38], it was reported that the use of probiotics in feed for fish and its inclusion in intensive aquaculture to promote healthy gut is growing. These researchers stated the need for alternative measures that will perform closely and effectively to the use of antibiotics after it was banned in the European Union (EU) in 2006. They stated that several definitions of probiotics mainly for aquaculture were considered. Among them is the definition that probiotics is described as "any microbial cell provided via the diet or rearing water that benefits the host fish, fish farmer, and fish consumer, which is achieved, in part at least, by improving the microbial balance of the fish." The authors regarded the direct benefits to the host fish as immunostimulants, improved disease resistance, reduced stress response, and improved gastrointestinal morphology. The benefits to the fish farmers and consumers include improved fish appetite, growth performance, feed utilization, improvement of carcass quality, flesh quality, and reduced malformations. It was explained that combining probiotics with prebiotics could improve the survival of the bacteria and enhance their effects in the large intestine [38]. Thus, probiotic and prebiotic effects might be additive or even synergistic (prebiotic is a nondigestible carbohydrate that helps to render harmful bacteria inactive).

Globally, food-producing animals consume 70–90% of genetically engineered (GE) crop biomass. Furthermore, many experimental studies have revealed that the performance and health of GE-fed animals are comparable with those fed isogenic non-GE crop lines [39].

In a mini review article [40], it was reported that probiotic live cells with different beneficial characteristics have been extensively studied and explored commercially in many different products in the world. Their benefits to young ruminants have been supported in several scientific articles. These benefits include enhanced development of the rumen microflora, improved digestion, and nitrogen flow toward lower digestive tract and improved meat and

which suppress proliferation of pathogenic bacteria in the intestines.

tion by the growing swine fed soybean meal-based diets.

plants were of good chemical composition and quality.

**6.3. Practical application of biotechnology in fish feeding**

**6.4. Practical application of biotechnology in ruminant feeding**

#### **6.1. Practical application of biotechnology in poultry feeding**

Nonnutritive feed additives such as the enzymes xylanases, β-glucanases, and phytates are used to overcome antinutritional effects in some grains and to improve overall nutrient availability and feed value. Antioxidants such as butylated hydroxyl toluene (BHT), butylated hydroxyl anisole (BHA), and ethoxyquin are used in poultry feeds to prevent auto-oxidation of fats and oils in poultry diets. Antifungals such as aflatoxins are added to poultry feed ingredients such as grains, groundnut cake, and cottonseed cake to control fungi growth in feed and to bind and reduce the negative effects of mycotoxins. Probiotics are used in poultry to encourage the growth of certain strains of bacteria in the gut at the expense of other less desirable microorganisms. Prebiotics (oligosaccharides) may function to bind harmful bacteria in the digestive system of poultry. In laying hens and broilers, research findings [35] showed that feeding recombinant DNA-produced crops and newly expressed proteins in genetically modified plants did not show chemical and physical properties different from those fed with native plants.

#### **6.2. Practical application of biotechnology in pig feeding**

In a research review article [36], it was reported that the quest to widen the narrow range of feed ingredients available to pig producers has prompted research on the use of low cost, unconventional feedstuffs, which are typically fibrous and abundant. Maize cob, a by-product of a major cereal grown worldwide, has potential to be used as a pig feed ingredient. Maize cob is usually either dumped or burnt for fuel. However, the major hindrance in the use of maize cobs in pig diets is their lignocellulosic nature (45–55% cellulose, 25–35% hemicellulose, and 20–30% lignin), which is not easily digestible by pigs' digestive enzymes. These researchers [36] explained that the high fiber in maize cobs (930 g neutral detergent fiber/ kg DM; 573 g acid detergent fiber/kg DM) increases the rate of passage and sequestration of nutrients in the fiber, thereby reducing their digestion. The application of simple techniques such as grinding, heat treatment such as sun-drying, and fermentation can modify the structure of the fibrous components in the maize cobs and improve their utilization. Pigs could extract up to 25% of energy maintenance requirements from fermentation products. Also, dietary fiber improves pig intestinal health by promoting the growth of lactic acid bacteria, which suppress proliferation of pathogenic bacteria in the intestines.

In another journal article [37], it was reported that in growing pigs, the effects of four dietary levels of microbial phytase (Natuphos) enzyme on the apparent and true digestibility of Ca, P, CP, and AA in dehulled soybean meal were assessed. In the study, the researchers observed that supplemental microbial phytase did not improve the utilization of amino acid provided by soybean meal but was an effective means of improving calcium and phosphorus utilization by the growing swine fed soybean meal-based diets.

It was observed that in pigs, feeding recombinant DNA produced crops and newly expressed proteins in genetically modified (GM) plants showed no biologically relevant effects on feed intake, digestibility, or animal health [35]. Also, there were no unintended effects on the performance and fertility of animals. The food products obtained from the pigs fed with GM plants were of good chemical composition and quality.

#### **6.3. Practical application of biotechnology in fish feeding**

**6. Practical application of biotechnology in monogastrics (poultry,** 

Biotechnology is offering a lot of opportunities for increasing agricultural productivity and for protecting the environment through the reduced use of agrochemicals [34]. Techniques of modern biology such as genetic manipulation of rumen microbes, and chemical and biological treatment of low-quality animal feeds for improved nutritive value among others have become a reality in the past few decades and are finding their ways into present research and development programs. These go along side with fleeting coverage of issues concerning the potential environmental hazards of genetic engineering and other biotechnologies, and the need for their ethical evaluation and for an international regulatory mechanism [34]. Practical application of biotechnology in monogastrics (poultry, pigs, and fish)

Nonnutritive feed additives such as the enzymes xylanases, β-glucanases, and phytates are used to overcome antinutritional effects in some grains and to improve overall nutrient availability and feed value. Antioxidants such as butylated hydroxyl toluene (BHT), butylated hydroxyl anisole (BHA), and ethoxyquin are used in poultry feeds to prevent auto-oxidation of fats and oils in poultry diets. Antifungals such as aflatoxins are added to poultry feed ingredients such as grains, groundnut cake, and cottonseed cake to control fungi growth in feed and to bind and reduce the negative effects of mycotoxins. Probiotics are used in poultry to encourage the growth of certain strains of bacteria in the gut at the expense of other less desirable microorganisms. Prebiotics (oligosaccharides) may function to bind harmful bacteria in the digestive system of poultry. In laying hens and broilers, research findings [35] showed that feeding recombinant DNA-produced crops and newly expressed proteins in genetically modified plants did not

show chemical and physical properties different from those fed with native plants.

In a research review article [36], it was reported that the quest to widen the narrow range of feed ingredients available to pig producers has prompted research on the use of low cost, unconventional feedstuffs, which are typically fibrous and abundant. Maize cob, a by-product of a major cereal grown worldwide, has potential to be used as a pig feed ingredient. Maize cob is usually either dumped or burnt for fuel. However, the major hindrance in the use of maize cobs in pig diets is their lignocellulosic nature (45–55% cellulose, 25–35% hemicellulose, and 20–30% lignin), which is not easily digestible by pigs' digestive enzymes. These researchers [36] explained that the high fiber in maize cobs (930 g neutral detergent fiber/ kg DM; 573 g acid detergent fiber/kg DM) increases the rate of passage and sequestration of nutrients in the fiber, thereby reducing their digestion. The application of simple techniques such as grinding, heat treatment such as sun-drying, and fermentation can modify the structure of the fibrous components in the maize cobs and improve their utilization. Pigs could

**pigs, and fish) and ruminants (cattle, sheep, and goats)**

160 Animal Husbandry and Nutrition

and in ruminants (cattle, sheep, and goats) is hereby discussed below.

**6.1. Practical application of biotechnology in poultry feeding**

**6.2. Practical application of biotechnology in pig feeding**

In a journal review article [38], it was reported that the use of probiotics in feed for fish and its inclusion in intensive aquaculture to promote healthy gut is growing. These researchers stated the need for alternative measures that will perform closely and effectively to the use of antibiotics after it was banned in the European Union (EU) in 2006. They stated that several definitions of probiotics mainly for aquaculture were considered. Among them is the definition that probiotics is described as "any microbial cell provided via the diet or rearing water that benefits the host fish, fish farmer, and fish consumer, which is achieved, in part at least, by improving the microbial balance of the fish." The authors regarded the direct benefits to the host fish as immunostimulants, improved disease resistance, reduced stress response, and improved gastrointestinal morphology. The benefits to the fish farmers and consumers include improved fish appetite, growth performance, feed utilization, improvement of carcass quality, flesh quality, and reduced malformations. It was explained that combining probiotics with prebiotics could improve the survival of the bacteria and enhance their effects in the large intestine [38]. Thus, probiotic and prebiotic effects might be additive or even synergistic (prebiotic is a nondigestible carbohydrate that helps to render harmful bacteria inactive).

#### **6.4. Practical application of biotechnology in ruminant feeding**

Globally, food-producing animals consume 70–90% of genetically engineered (GE) crop biomass. Furthermore, many experimental studies have revealed that the performance and health of GE-fed animals are comparable with those fed isogenic non-GE crop lines [39].

In a mini review article [40], it was reported that probiotic live cells with different beneficial characteristics have been extensively studied and explored commercially in many different products in the world. Their benefits to young ruminants have been supported in several scientific articles. These benefits include enhanced development of the rumen microflora, improved digestion, and nitrogen flow toward lower digestive tract and improved meat and milk production during the adult stage of the ruminant. The author reported that in order to attain higher profit margin in intensive small ruminant production, farmers are now shifting from traditional to high input feeding systems. He explained that in order to harvest real benefits from small ruminants, which are raised on nutrient-rich diets, feed additives like probiotics are needed to be used to enhance the efficiencies of nutrient utilization in growing ruminants. Thus, the more feed an animal consumes each day, the greater would be the opportunity for increasing its daily production. Probiotic supplementation was found to increase feed intake and to influence performance of ruminants [40]. Also, the use of probiotics in a healthy animal stimulated nonspecific immune response and enhanced the system of immune protection. The probiotic that enhanced immunoglobulin level may have more positive effect on growth performance, production, and ability to resist diseases. Examples of probiotics suggested were those containing *Lactobacillus plantarum* (which breakdown carbohydrates into glucose) and *Aspergillus oryzae* (which produce enzymes that are involved in the digestion of carbohydrates and fiber) [40]. Some other researchers [41] observed that the addition of probiotic containing yeast in supplemental diet enhanced growth performance and immune response of Zandi lambs. Another study was conducted that involved a 765-day trial [42]. This trial included two lactations, using nine primiparous, and nine multiparous dairy cows. The experimental cows were fed diets containing whole crop silage, kernels, and whole crop cobs from GE corn and its isogenic non-GE counterpart. There were no significant differences in the gene expression profiles of the cows fed either the transgenic or the near-isogenic rations [42]. Similarly, dairy cows, beef cattle, and other ruminants were fed recombinant DNA-produced crops and newly expressed proteins in genetically modified plants (GMP) [35]. There were no unintended effects in composition and contamination of genetically modified plants compared with isogenic counterparts. Rather, there were lower mycotoxin concentrations in GMP with *Bacillus thuringiensis* (Bt) [35].

10-fold the maximum recommended dosage. Studies on the effect of the microbial additive on the microflora of the digestive tract are also required when claim is made concerning an

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**Consumer safety assessment**: certain toxicological tests are required to be performed to exclude the possibility that when the probiotic product or microbial additive is accumulated in the target animal, it will not form a consumer risk. The test includes both genotoxicity studies (a metaphase cytogenetic assay and other *in vivo* and *in vitro* studies) and oral toxicity test

Nanotechnology is described as the study of materials at the nanoscale, with at least one dimension generally ranging between 1 and 100 nm (10−9 to 10−7 m) [7]. Nanomaterials are best referred to as particles. There are three basic systems of nanoparticles in their applications; that is, nanoparticles can serve as a whole functional unit, or as a delivery vehicle for materials conjugated to their surface, or as encapsulated within. The application of nanotechnology in animal production is new as production in livestock industry has been centered on the use of antibiotics as growth promoters [7]. However, there has been much anxiety globally over microbial antibiotic resistance, and laws and regulations are being updated to ban in-feed antibiotic use in the livestock production industry. This has thus set in motion the search for alternatives for animal growth promoters and antimicrobials for inclusion in animal diets. Nanoparticles may present a feasible alternative to antibiotics and may help bar pathogens from entering animal production sites. Metal nanoparticles with net positive charges are drawn to negatively charged bacterial membranes, resulting in leakage and bacterial lysis [44]. There has been the discovery of the use of nanoparticles for nutrient delivery into livestock feeds. Copper is regularly added to feeds for its ability to promote animal growth and performance in addition to its antimicrobial properties [45]. In another research [46], it was demonstrated that nanoform copper could better improve piglet energy and crude fat digestion through the augmentation of lipase and phospholipase A activity in the small intestine compared to a basal diet

done to ascertain whether antibiotics in feed can be completely replaced by nano-antimicrobials. Also, despite the expansion of antibiotic resistance in bacteria, antibiotics have not yet been rendered totally ineffective. However, their delivery and efficacy may be enhanced by nanoparticle carriers, and thus substantially decreasing the dosage of antibiotics required for treatment. Thus, it was stated that the inclusion of nutrient supplements in livestock feed, regardless of particle size, may benefit the producer if there is still consumer demand for the final product [7]. These authors [7] further explained that if for example, meat and eggs obtained from an animal fed nanoparticle supplements are

). However, further investigations need to be

**7. The application of nanotechnology in livestock nutrition and** 

effect on the intestinal microflora.

(a 90-day in-feed or drinking water).

supplemented with copper sulfate (CuSo4

**feeding**

#### **6.5. The European Union requirements for the assessment of probiotics or microbial feed additive usage**

**The following guidelines of usage should be followed**: the identity of the product (proposed proprietary name) should be stated. There should be characterization of the active agents (nomenclature, biological origin, genetic modification, compliance with released directive for genetically modified organisms (GMOs), toxin production, virulence factors, antibiotic production and antibiotic resistance, and other relevant properties). Then, the conditions for the usage of the microbial feed additive should be given [43].

**Safety guidelines under the conditions for use**: there should be performed a detailed safety assessment.

**Studies on target species**: studies should be carried out on target species or animals of different categories to determine the safety margin for each species. The aim of this trial is to evaluate for the target animal the risk of an accidental overdosing that could originate during feed production (mixing heterogeneity). This trial shall be conducted at a dosage being at least 10-fold the maximum recommended dosage. Studies on the effect of the microbial additive on the microflora of the digestive tract are also required when claim is made concerning an effect on the intestinal microflora.

**Consumer safety assessment**: certain toxicological tests are required to be performed to exclude the possibility that when the probiotic product or microbial additive is accumulated in the target animal, it will not form a consumer risk. The test includes both genotoxicity studies (a metaphase cytogenetic assay and other *in vivo* and *in vitro* studies) and oral toxicity test (a 90-day in-feed or drinking water).

## **7. The application of nanotechnology in livestock nutrition and feeding**

milk production during the adult stage of the ruminant. The author reported that in order to attain higher profit margin in intensive small ruminant production, farmers are now shifting from traditional to high input feeding systems. He explained that in order to harvest real benefits from small ruminants, which are raised on nutrient-rich diets, feed additives like probiotics are needed to be used to enhance the efficiencies of nutrient utilization in growing ruminants. Thus, the more feed an animal consumes each day, the greater would be the opportunity for increasing its daily production. Probiotic supplementation was found to increase feed intake and to influence performance of ruminants [40]. Also, the use of probiotics in a healthy animal stimulated nonspecific immune response and enhanced the system of immune protection. The probiotic that enhanced immunoglobulin level may have more positive effect on growth performance, production, and ability to resist diseases. Examples of probiotics suggested were those containing *Lactobacillus plantarum* (which breakdown carbohydrates into glucose) and *Aspergillus oryzae* (which produce enzymes that are involved in the digestion of carbohydrates and fiber) [40]. Some other researchers [41] observed that the addition of probiotic containing yeast in supplemental diet enhanced growth performance and immune response of Zandi lambs. Another study was conducted that involved a 765-day trial [42]. This trial included two lactations, using nine primiparous, and nine multiparous dairy cows. The experimental cows were fed diets containing whole crop silage, kernels, and whole crop cobs from GE corn and its isogenic non-GE counterpart. There were no significant differences in the gene expression profiles of the cows fed either the transgenic or the near-isogenic rations [42]. Similarly, dairy cows, beef cattle, and other ruminants were fed recombinant DNA-produced crops and newly expressed proteins in genetically modified plants (GMP) [35]. There were no unintended effects in composition and contamination of genetically modified plants compared with isogenic counterparts. Rather, there were lower

mycotoxin concentrations in GMP with *Bacillus thuringiensis* (Bt) [35].

usage of the microbial feed additive should be given [43].

**feed additive usage**

162 Animal Husbandry and Nutrition

assessment.

**6.5. The European Union requirements for the assessment of probiotics or microbial** 

**The following guidelines of usage should be followed**: the identity of the product (proposed proprietary name) should be stated. There should be characterization of the active agents (nomenclature, biological origin, genetic modification, compliance with released directive for genetically modified organisms (GMOs), toxin production, virulence factors, antibiotic production and antibiotic resistance, and other relevant properties). Then, the conditions for the

**Safety guidelines under the conditions for use**: there should be performed a detailed safety

**Studies on target species**: studies should be carried out on target species or animals of different categories to determine the safety margin for each species. The aim of this trial is to evaluate for the target animal the risk of an accidental overdosing that could originate during feed production (mixing heterogeneity). This trial shall be conducted at a dosage being at least Nanotechnology is described as the study of materials at the nanoscale, with at least one dimension generally ranging between 1 and 100 nm (10−9 to 10−7 m) [7]. Nanomaterials are best referred to as particles. There are three basic systems of nanoparticles in their applications; that is, nanoparticles can serve as a whole functional unit, or as a delivery vehicle for materials conjugated to their surface, or as encapsulated within. The application of nanotechnology in animal production is new as production in livestock industry has been centered on the use of antibiotics as growth promoters [7]. However, there has been much anxiety globally over microbial antibiotic resistance, and laws and regulations are being updated to ban in-feed antibiotic use in the livestock production industry. This has thus set in motion the search for alternatives for animal growth promoters and antimicrobials for inclusion in animal diets. Nanoparticles may present a feasible alternative to antibiotics and may help bar pathogens from entering animal production sites. Metal nanoparticles with net positive charges are drawn to negatively charged bacterial membranes, resulting in leakage and bacterial lysis [44]. There has been the discovery of the use of nanoparticles for nutrient delivery into livestock feeds. Copper is regularly added to feeds for its ability to promote animal growth and performance in addition to its antimicrobial properties [45]. In another research [46], it was demonstrated that nanoform copper could better improve piglet energy and crude fat digestion through the augmentation of lipase and phospholipase A activity in the small intestine compared to a basal diet supplemented with copper sulfate (CuSo4 ). However, further investigations need to be done to ascertain whether antibiotics in feed can be completely replaced by nano-antimicrobials. Also, despite the expansion of antibiotic resistance in bacteria, antibiotics have not yet been rendered totally ineffective. However, their delivery and efficacy may be enhanced by nanoparticle carriers, and thus substantially decreasing the dosage of antibiotics required for treatment. Thus, it was stated that the inclusion of nutrient supplements in livestock feed, regardless of particle size, may benefit the producer if there is still consumer demand for the final product [7]. These authors [7] further explained that if for example, meat and eggs obtained from an animal fed nanoparticle supplements are enhanced and are indiscernible from the original product, then they are likely to still be favorable to consumers. These researchers mentioned that it is, however, important to understand the role of the nanoparticle as an additive in a given biological system and the by-products from that system and to ensure that it is safe for consumption before its application in livestock production.

and the development of antibiotic resistance in livestock and in humans should be kept at minimum levels. These could be checked through continuous enforcement of guidelines in the use of feed additives and microbials. Further expectations about the future improvement in livestock feeding could involve the application of nanoparticles in livestock feeds and feeding to enhance animal nutrition, growth, and performance. The biosafety of the use of nanotechnology, however, needs to be ascertained. Possible risk control in the application of microbials and nanotechnology could include continuous monitoring and control of biological and environmental safety, in terms of guarding against the re-emergence of livestock and

Current and Future Improvements in Livestock Nutrition and Feed Resources

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165

The author gratefully acknowledges useful suggestions given by Prof. David F. Apata at the

Department of Animal Production and Health, Ladoke Akintola University of Technology,

[1] Food and Agricultural Organization (FAO). The state of food and agriculture. 1989.

[2] Kaasschieter GA, de Jong R, Schiere JB, Zwart D. Towards a sustainable livestock production in developing countries and the importance of animal health strategy therein.

[3] Wanapat M, Kang S, Polyorach S. Development of feeding systems and strategies of supplementation to enhance rumen fermentation and ruminant production in the tropics. Journal of Animal Science and Biotechnology. 2013;**4**(32):1-11. Available from: http://

[4] Asmare B. Biotechnological advances for animal nutrition and feed improvement. World Journal of Agricultural Research. 2014;**2**(3):115-118. Available from: http://pubs.sciepub.

Veterinary Quarterly. 1992;**14**(2):66-75. DOI: 10.1080/01652176.1992.9694333

Available from: www.fao.org/docrep/017/t0162e/t0162e.pdf

human diseases and antibiotic resistance through the livestock feed industry.

**Acknowledgements**

**Author details**

Grace Opadoyin Tona

Ogbomoso, Nigeria

**References**

planning stage of this write-up.

Address all correspondence to: gotona@lautech.edu.ng

www.jasbsci.com/content/4/1/32

com/wjar/2/3/5

#### **7.1. Future prospects**

As nanotechnology continues to develop and gain more attention, its application would grow wider in the livestock industry [7]. Thus, nanoparticles may have to be used alongside the use of antibiotics until it gains more understanding and global acceptance.

## **8. Conclusion**

In conclusion, continuous provision of adequate quantity and quality of nutritious feeds for livestock is necessary to sustain the livestock industry. This is not negotiable now that human population is growing exponentially in the twenty-first century. The adoption of new biotechnological applications and biosafety in livestock nutrition and feeding systems is necessary in order to promote improvements in current and future global livestock production. The main cost of livestock production is on the production of concentrate feeds. Alternative feed resources should be properly utilized, and low nutrient quality feeds should be improved upon by the use of various technologies, for better utilization by livestock. There could be the optimizing of production of high-quality forages such as genetically engineered forages with high nutrient contents and genetically manipulated for more digestible cell wall components. Generally, focus could be directed at meeting the nutritional requirements of livestock through biotechnological applications. In the developing countries, particularly during the dry season when forage is scarce, there could be the substitution of forage with nutrient detergent fiber (NDF-)rich feeds and feedstuffs. These may include crop residues, agroindustrial by-products and other feedstuffs that are of little or no value in human feeding. There could be the development of carefully balanced partial or total mixed rations.

Meeting the nutritional need and varied dietary preferences of the growing global population is also needed. This could be addressed through continuous development of better quality feeds for quality livestock products and by-products. The adoption of new biotechnological applications and bio-safety in livestock nutrition and feeding systems is necessary in order to promote improvements in current and future global livestock production. There should be the development and use of biologically safe animal feeds for the production of economically viable and safe animal products. Therefore, the production of feed ingredients that would be affordable for livestock producers with minimum use of chemical additives and use of locally available feed resources is paramount.

Future improvements in livestock feed resources could be based on the application of biotechnology such as use of safe antibiotic replacers. Probiotics and prebiotics could be employed to improve animal performance. The risks that may be involved in the use of antibiotics and the development of antibiotic resistance in livestock and in humans should be kept at minimum levels. These could be checked through continuous enforcement of guidelines in the use of feed additives and microbials. Further expectations about the future improvement in livestock feeding could involve the application of nanoparticles in livestock feeds and feeding to enhance animal nutrition, growth, and performance. The biosafety of the use of nanotechnology, however, needs to be ascertained. Possible risk control in the application of microbials and nanotechnology could include continuous monitoring and control of biological and environmental safety, in terms of guarding against the re-emergence of livestock and human diseases and antibiotic resistance through the livestock feed industry.

## **Acknowledgements**

enhanced and are indiscernible from the original product, then they are likely to still be favorable to consumers. These researchers mentioned that it is, however, important to understand the role of the nanoparticle as an additive in a given biological system and the by-products from that system and to ensure that it is safe for consumption before its

As nanotechnology continues to develop and gain more attention, its application would grow wider in the livestock industry [7]. Thus, nanoparticles may have to be used alongside the use

In conclusion, continuous provision of adequate quantity and quality of nutritious feeds for livestock is necessary to sustain the livestock industry. This is not negotiable now that human population is growing exponentially in the twenty-first century. The adoption of new biotechnological applications and biosafety in livestock nutrition and feeding systems is necessary in order to promote improvements in current and future global livestock production. The main cost of livestock production is on the production of concentrate feeds. Alternative feed resources should be properly utilized, and low nutrient quality feeds should be improved upon by the use of various technologies, for better utilization by livestock. There could be the optimizing of production of high-quality forages such as genetically engineered forages with high nutrient contents and genetically manipulated for more digestible cell wall components. Generally, focus could be directed at meeting the nutritional requirements of livestock through biotechnological applications. In the developing countries, particularly during the dry season when forage is scarce, there could be the substitution of forage with nutrient detergent fiber (NDF-)rich feeds and feedstuffs. These may include crop residues, agroindustrial by-products and other feedstuffs that are of little or no value in human feeding. There could be the development of carefully balanced partial or total mixed rations.

Meeting the nutritional need and varied dietary preferences of the growing global population is also needed. This could be addressed through continuous development of better quality feeds for quality livestock products and by-products. The adoption of new biotechnological applications and bio-safety in livestock nutrition and feeding systems is necessary in order to promote improvements in current and future global livestock production. There should be the development and use of biologically safe animal feeds for the production of economically viable and safe animal products. Therefore, the production of feed ingredients that would be affordable for livestock producers with minimum use of chemical additives and use of locally available feed resources is paramount. Future improvements in livestock feed resources could be based on the application of biotechnology such as use of safe antibiotic replacers. Probiotics and prebiotics could be employed to improve animal performance. The risks that may be involved in the use of antibiotics

of antibiotics until it gains more understanding and global acceptance.

application in livestock production.

**7.1. Future prospects**

164 Animal Husbandry and Nutrition

**8. Conclusion**

The author gratefully acknowledges useful suggestions given by Prof. David F. Apata at the planning stage of this write-up.

## **Author details**

Grace Opadoyin Tona

Address all correspondence to: gotona@lautech.edu.ng

Department of Animal Production and Health, Ladoke Akintola University of Technology, Ogbomoso, Nigeria

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iiste.org

168 Animal Husbandry and Nutrition

dairyscience.org/issues

antibiotic-resistance.html

from: https://www.feedipedia.org

Articles/Fuller%2019

2015;**3**(2):132. DOI: 10.4172/2329-8901.1000132


**Chapter 8**

**Provisional chapter**

) and the production

), and pregnancy (*k*p)

) are known, the energy losses by gas and heat

), and pregnancy (NEp). NE is, in fact, what is used by the

**Respirometry and Ruminant Nutrition**

**Respirometry and Ruminant Nutrition**

DOI: 10.5772/intechopen.73009

Ricardo Reis e Silva, Ana Luiza Costa Cruz Borges,

Ricardo Reis e Silva, Ana Luiza Costa Cruz Borges,

André Santos Souza, Paolo Antonio Dutra Vivenza,

André Santos Souza, Paolo Antonio Dutra Vivenza,

Juliana Sávia da Silva, Helena Ferrreira Lage, Alexandre Lima Ferreira, Lúcio Carlos Gonçalves,

Juliana Sávia da Silva, Helena Ferrreira Lage, Alexandre Lima Ferreira, Lúcio Carlos Gonçalves,

Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution,

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use,

distribution, and reproduction in any medium, provided the original work is properly cited.

and reproduction in any medium, provided the original work is properly cited.

The gaseous exchange between an organism and the environment is measured by respi-

can be calculated. Energy metabolism and methane production have been studied in the Calorimetry and Metabolism Laboratory of the Federal University of Minas Gerais, located in Belo Horizonte, Minas Gerais, Brazil. Animals used are mainly Zebu cattle and their crossbreeds that represent most beef and dairy cattle breed grazed on tropical pastures. System calibration and routine work are addressed in this text. The results obtained on respirometric chambers are expressed in net energy (NE), which can be net energy for maintenance (NEm),

animal for maintenance and each productive function. The values of *k* (conversion efficiency

are determined. Thanks to the peculiarity of the respirometric technique, the same animal can be evaluated several times, in different physiological states and planes of nutrition. **Keywords:** bovine, calorimetry, energy metabolism, gases, nutrient requirements

rometry or indirect calorimetry. Once the oxygen consumption (O2

of ME into NE) for maintenance (*k*m), milk (*k*L), weight gain or growth (*k*<sup>g</sup>

) and methane (CH4

Eloisa Oliveira Simões Saliba, Iran Borges,

Eloisa Oliveira Simões Saliba, Iran Borges,

Pedro Henrique de Araujo Carvalho,

Pedro Henrique de Araujo Carvalho,

Warley Efrem Campos and Norberto Mario Rodriguez

**Abstract**

Warley Efrem Campos and Norberto Mario Rodriguez

http://dx.doi.org/10.5772/intechopen.73009

of carbon dioxide (CO2

lactation (NEL), weight gain (NEg

**Provisional chapter**

## **Respirometry and Ruminant Nutrition**

Ricardo Reis e Silva, Ana Luiza Costa Cruz Borges,

**Respirometry and Ruminant Nutrition**

DOI: 10.5772/intechopen.73009

Ricardo Reis e Silva, Ana Luiza Costa Cruz Borges, Pedro Henrique de Araujo Carvalho, André Santos Souza, Paolo Antonio Dutra Vivenza, Juliana Sávia da Silva, Helena Ferrreira Lage, Alexandre Lima Ferreira, Lúcio Carlos Gonçalves, Eloisa Oliveira Simões Saliba, Iran Borges, Warley Efrem Campos and Norberto Mario Rodriguez Pedro Henrique de Araujo Carvalho, André Santos Souza, Paolo Antonio Dutra Vivenza, Juliana Sávia da Silva, Helena Ferrreira Lage, Alexandre Lima Ferreira, Lúcio Carlos Gonçalves, Eloisa Oliveira Simões Saliba, Iran Borges, Warley Efrem Campos and Norberto Mario Rodriguez Additional information is available at the end of the chapter

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/intechopen.73009

#### **Abstract**

The gaseous exchange between an organism and the environment is measured by respirometry or indirect calorimetry. Once the oxygen consumption (O2 ) and the production of carbon dioxide (CO2 ) and methane (CH4 ) are known, the energy losses by gas and heat can be calculated. Energy metabolism and methane production have been studied in the Calorimetry and Metabolism Laboratory of the Federal University of Minas Gerais, located in Belo Horizonte, Minas Gerais, Brazil. Animals used are mainly Zebu cattle and their crossbreeds that represent most beef and dairy cattle breed grazed on tropical pastures. System calibration and routine work are addressed in this text. The results obtained on respirometric chambers are expressed in net energy (NE), which can be net energy for maintenance (NEm), lactation (NEL), weight gain (NEg ), and pregnancy (NEp). NE is, in fact, what is used by the animal for maintenance and each productive function. The values of *k* (conversion efficiency of ME into NE) for maintenance (*k*m), milk (*k*L), weight gain or growth (*k*<sup>g</sup> ), and pregnancy (*k*p) are determined. Thanks to the peculiarity of the respirometric technique, the same animal can be evaluated several times, in different physiological states and planes of nutrition.

**Keywords:** bovine, calorimetry, energy metabolism, gases, nutrient requirements

Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons

## **1. Introduction**

Calorimetry is the process of measuring heat production in the body; it can be direct or indirect. In the first case, produced heat is measured by increasing ambient temperatures. Indirect calorimetry measures heat produced by the animal through the quantification of metabolism products, for example, the gas exchanges with the environment [2].

the animal died. In the next century, John Priestly (1733–1804) found evidence of the diversity of gases that compose atmospheric air (such as carbon dioxide and nitrogen) and observed that different chemical reactions could produce gases capable of sustaining life [3].Although such researchers have contributed brilliantly to the understanding of bioenergetics, the scientist Antonie Lavoisier (1743–1794) deserves special attention for the great importance of his discoveries. He discovered the existence and importance of the gas he named "*oxigène*" (oxygen). For Lavoisier, breathing was defined as a slow combustion process. His studies led to the creation of indirect calorimetry (which allows the evaluation of metabolic rates through oxygen consumption, changes according to exercise and diet), as well as direct calorimetry: when a mouse is surrounded by ice, heat production of the animal can be evaluated by the

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 173

A fundamental advance in calorimetry development was the postulation of the first law of thermodynamics by the German Julius Robert von Mayer (1814–1878) in 1842, based on observations made by the Swiss chemist Germain Henry Hess (1802–1850). The first law, known as the "mass preservation law," tells us that energy can be transferred or transformed, but it cannot be destroyed or created. Later, in his work on the equivalence between work and heat, James Prescott Joule (1818–1889) eventually corroborated the concept proposed by Mayer in

Still, in the nineteenth century, Berthelot (1827–1907) developed the adiabatic calorimetric pump. Its creation obeyed the principle of thermodynamics that energy is only transferred; therefore, the energy released in heat form during the combustion of an organic substance would be equivalent to the available gross energy in case of a food or loss by the organism, in case of excreta.

The development of bioenergetics concepts exploring the interrelationship between gas exchange and heat production had a significant advance with the work of Carl Von Voit, who used an open circuit respirometry apparatus developed by Max Von Pettenkofer (1818–1901). Other researchers (all Von Voit students) such as Henry Armsby, Wilbur Atwater, Oskar Kellner, and Max Rubner, using similar equipment, have developed work on energy metabolism [5].

Kellner and Köhler (1900), cited by [6], developed the "starch equivalent" concept, using a system based on foods net energy, in which foods energy value presented a relation to starch energy content, which has been used for many years in Europe and Russia, also serving as the basis for the development of later feeding systems. At the same time, Atwater and Bryant developed the physiological fuel values system to determine the metabolizable energy values of carbohydrates, fats and proteins—this energy value is corrected for the energy value of the excreted urea. Armsby (1903, 1907), also using respirometric calorimetry, developed the concept of net energy and defined the metabolizable energy (ME) as the net energy (or retained

It is noteworthy that the system proposed by Armsby at the beginning of the twentieth contains many of the principles used for the development of current net energy systems, such as [7, 6].

Another important advance in modern calorimetry, however, would only occur in 1965, with the publication of Brouwer's equation [8]. The equation (Eq. 1) allowed the calculation of the

energy, RE) plus the food heat increment (HI) (ME = RE + HI).

formation of water in the liquid state [4].

relation to energy conservation [5].

heat production.

The Animal Metabolism and Calorimetry Laboratory (LAMACA), located at the Veterinary School of Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil, is a pioneer in the construction of respirometric chambers in Latin America (**Figure 1**). The first experiment started in 2006 with small ruminants and since 2008, this kind of research has been carried out to evaluate the energy metabolism and the production of methane by cattle. The results obtained are expressed in net energy (NE), which can be net energy for maintenance (NEm), net energy for milk production (NEL), net energy for weight gain (NEg ), and net energy for gestation (NEp). We can determine what was truly used by the animal in described productive functions. Conversion factors of total digestible nutrients (TDN) for digestible energy (DE) and metabolizable energy (ME) are calculated and the latter for each physiological function or NE. The *k* values are determined (conversion efficiency of ME in NE) for maintenance (*k*m), milk yield (*k*L), weight gain or growth (*k*<sup>g</sup> ) and gestation (*k*p).

In this chapter, basic concepts of indirect calorimetry or respirometry are presented; some notes about the use of this methodology in the research into metabolism and nutrition of cattle in the laboratory are also included.

**Figure 1.** Respirometric chamber's design at LAMACA.

## **2. Calorimetry: concepts and basic principals**

Several researches throughout history have energy as the focus of their study. In one of the first works, Leonardo Da Vinci, in his publication "Codex Atlanticus" postulated that where flame does not live no animal that breathes cannot live. Subsequently, Robert Boyle (1627– 1691) concluded that both combustion and life necessitated a substance present in the air. The same observation relating "fire x life" was made by his contemporary, the scientist John Mayow (1643–1691), who built the first semi-quantitative "respirometer" and observed that by placing a candle and a mouse under a single flask, soon after the candle flame went out, the animal died. In the next century, John Priestly (1733–1804) found evidence of the diversity of gases that compose atmospheric air (such as carbon dioxide and nitrogen) and observed that different chemical reactions could produce gases capable of sustaining life [3].Although such researchers have contributed brilliantly to the understanding of bioenergetics, the scientist Antonie Lavoisier (1743–1794) deserves special attention for the great importance of his discoveries. He discovered the existence and importance of the gas he named "*oxigène*" (oxygen). For Lavoisier, breathing was defined as a slow combustion process. His studies led to the creation of indirect calorimetry (which allows the evaluation of metabolic rates through oxygen consumption, changes according to exercise and diet), as well as direct calorimetry: when a mouse is surrounded by ice, heat production of the animal can be evaluated by the formation of water in the liquid state [4].

**1. Introduction**

172 Animal Husbandry and Nutrition

Calorimetry is the process of measuring heat production in the body; it can be direct or indirect. In the first case, produced heat is measured by increasing ambient temperatures. Indirect calorimetry measures heat produced by the animal through the quantification of metabolism

The Animal Metabolism and Calorimetry Laboratory (LAMACA), located at the Veterinary School of Federal University of Minas Gerais, Belo Horizonte, Minas Gerais, Brazil, is a pioneer in the construction of respirometric chambers in Latin America (**Figure 1**). The first experiment started in 2006 with small ruminants and since 2008, this kind of research has been carried out to evaluate the energy metabolism and the production of methane by cattle. The results obtained are expressed in net energy (NE), which can be net energy for mainte-

energy for gestation (NEp). We can determine what was truly used by the animal in described productive functions. Conversion factors of total digestible nutrients (TDN) for digestible energy (DE) and metabolizable energy (ME) are calculated and the latter for each physiological function or NE. The *k* values are determined (conversion efficiency of ME in NE) for main-

In this chapter, basic concepts of indirect calorimetry or respirometry are presented; some notes about the use of this methodology in the research into metabolism and nutrition of cattle

Several researches throughout history have energy as the focus of their study. In one of the first works, Leonardo Da Vinci, in his publication "Codex Atlanticus" postulated that where flame does not live no animal that breathes cannot live. Subsequently, Robert Boyle (1627– 1691) concluded that both combustion and life necessitated a substance present in the air. The same observation relating "fire x life" was made by his contemporary, the scientist John Mayow (1643–1691), who built the first semi-quantitative "respirometer" and observed that by placing a candle and a mouse under a single flask, soon after the candle flame went out,

) and gestation (*k*p).

), and net

nance (NEm), net energy for milk production (NEL), net energy for weight gain (NEg

products, for example, the gas exchanges with the environment [2].

tenance (*k*m), milk yield (*k*L), weight gain or growth (*k*<sup>g</sup>

**2. Calorimetry: concepts and basic principals**

**Figure 1.** Respirometric chamber's design at LAMACA.

in the laboratory are also included.

A fundamental advance in calorimetry development was the postulation of the first law of thermodynamics by the German Julius Robert von Mayer (1814–1878) in 1842, based on observations made by the Swiss chemist Germain Henry Hess (1802–1850). The first law, known as the "mass preservation law," tells us that energy can be transferred or transformed, but it cannot be destroyed or created. Later, in his work on the equivalence between work and heat, James Prescott Joule (1818–1889) eventually corroborated the concept proposed by Mayer in relation to energy conservation [5].

Still, in the nineteenth century, Berthelot (1827–1907) developed the adiabatic calorimetric pump. Its creation obeyed the principle of thermodynamics that energy is only transferred; therefore, the energy released in heat form during the combustion of an organic substance would be equivalent to the available gross energy in case of a food or loss by the organism, in case of excreta.

The development of bioenergetics concepts exploring the interrelationship between gas exchange and heat production had a significant advance with the work of Carl Von Voit, who used an open circuit respirometry apparatus developed by Max Von Pettenkofer (1818–1901). Other researchers (all Von Voit students) such as Henry Armsby, Wilbur Atwater, Oskar Kellner, and Max Rubner, using similar equipment, have developed work on energy metabolism [5].

Kellner and Köhler (1900), cited by [6], developed the "starch equivalent" concept, using a system based on foods net energy, in which foods energy value presented a relation to starch energy content, which has been used for many years in Europe and Russia, also serving as the basis for the development of later feeding systems. At the same time, Atwater and Bryant developed the physiological fuel values system to determine the metabolizable energy values of carbohydrates, fats and proteins—this energy value is corrected for the energy value of the excreted urea. Armsby (1903, 1907), also using respirometric calorimetry, developed the concept of net energy and defined the metabolizable energy (ME) as the net energy (or retained energy, RE) plus the food heat increment (HI) (ME = RE + HI).

It is noteworthy that the system proposed by Armsby at the beginning of the twentieth contains many of the principles used for the development of current net energy systems, such as [7, 6].

Another important advance in modern calorimetry, however, would only occur in 1965, with the publication of Brouwer's equation [8]. The equation (Eq. 1) allowed the calculation of the heat production.

Heat production

$$HP = \left< 3.866 \times O\_2 \right> + \left< 1.2 \times CO\_2 \right> - \left< 0.518 \times CH\_4 \right> - (1.431 \times N) \tag{1}$$

Air temperature and circulation inside the chamber are controlled. Air renewal is regulated by a mass flowmeter (model SABLE Flow-kit 500H). The flow rate is between 0.5 and 1 L/kg body weight/minute. The air leaving the chamber is piped to an outside area, and samples are pumped to gas analyzers. These are in the bypass system, that is, all are interconnected, allowing the passage of a single sample through all the analyzers. The gas analyzers used in this experiment come from the company SABLE SYSTEMS®, with the following models

Gas reading in the analyzers occurs in 5 min cycles. At the beginning of each cycle, the circuit is automatically moved by the equipment to a piping, which is connected to an outside area outside and an air sample is collected. The external air sample (atmospheric), called "baseline," circulates throughout the circuit until the gaseous material is analyzed. The system is then shifted to a closed sampling loop and the air is sampled from the chamber interior and analyzed. The baseline and the gas sample pass continuously through the system for 5 min. The data reading occurs in the last 30 s (the first 4 min 30 s were for ensuring that there were no residuals from the samples). Animal oxygen consumption, methane, and carbon dioxide production are calculated by the difference between external air concentrations and the chamber air. Due to the gaseous nature of the material, the control of temperature, pressure, and humidity of the system is very important, since these factors are responsible for changes in the volumes of each gas evaluated in relation to the temperature and pressure normal conditions. The chamber is constructed of steel and has two opposing openings, one that allows the entrance and exit of the animal (larger door, 2 m length and 2.2 m height) and one for feeding, with minimum air displacement, in the

windows, sealed, which allow the visualization of the animal and the interior of the chamber, as well as another animal, placed parallel to the chamber, in a cage. The internal volume of the

Due to the complexity of this system, it is necessary to determine a correction factor for the whole system [9], in order to have a correlation between reading and actual gas concentrations.

Gas analyzer calibration shall be performed whenever the equipment is used. Gases are injected in a constant flow and known concentrations. After stabilization, the read value is an adjustment to the actual value. Pure nitrogen is used to calibrate the analyzer for zero

because they are diluted in nitrogen (5 and 1%, respectively). Stabilization is inversely proportional to the gas aliquot directed to the devices. LAMACA uses 0.2 L/min flow [10], which

 analyzer calibration. The results for methane, carbon dioxide production, and oxygen consumption, as well as the animal heat production, were compared. All tests had best results

analyzer, and MA-1 CH<sup>4</sup>

(1 m long and 0.75 m high). On the sides, there are acrylic

, CO2

and CH4

, and methane analyzers.

have a known concentration

air concentration as constant.

in nitrogen) were evaluated to carry out

analyzer.

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 175

analyzer, CA-2A CO2

being used: TA-1B O<sup>2</sup>

front part, with an area of 0.75 m<sup>2</sup>

**4. Daily analyzer calibration**

concentration, while atmospheric air is used to calibrate the O2

with atmospheric air; then, we chose it for all analyses, with O2

requires approximately 5 min for values stabilization.

Atmospheric air or standard gas (21% diluted O<sup>2</sup>

concentration is 20.946%. The CO<sup>2</sup>

camera is 22.391 L.

Atmospheric air O2

the O2

where HP is the heat production; O<sup>2</sup> is the O2 volume, L; CO2 is the CO2 volume, L; CH4 is the CH4 volume, L; N is the urinary nitrogen.

The food, feces, and urine crude energy are determined by caloric pump. Brouwer's equation allows the calculation of heat production by an animal, after evaluation of produced gases over time. A range of possibilities open up in the study of energy metabolism of animals, including food assessment and determination of nutrient requirements.

## **3. Open circuit respirometry system**

LAMACA's respirometric chambers operate in open circuit system (**Figure 2**). The animal is housed in a chamber with a sealing that does not allow any gas exchange with the outside air, except by a proper air circulation system. Air tubing is coupled to a pump, which performs the renewal of air inside the chamber in a constant flow during the measurement, regulated by a mass flow meter, which corrects the airflow as a function of temperature, pressure, and humidity. According to [8], the flow control system represents a major limitation of this method, since the accuracy of this measurement is indispensable for the proper functioning of the system.

The air inside the chamber is continuously renewed by the constant input of external air. The input of fresh air into the chamber is possible due to the negative pressure created by the pump that promotes the suction of the internal air, thus allowing the entrance of external air. There is a renewal of the inside air that can be used for sampling and later evaluation by the gas analyzers. The internal negative pressure guarantees safety in the data acquisition because it prevents leakage of the air, which could constitute a source of errors in the analysis of the sampled gas.

**Figure 2.** Respirometric chambers for large animal (left) and small animal (right), presented by its designer, professor Norberto Mário Rodriguez.

Air temperature and circulation inside the chamber are controlled. Air renewal is regulated by a mass flowmeter (model SABLE Flow-kit 500H). The flow rate is between 0.5 and 1 L/kg body weight/minute. The air leaving the chamber is piped to an outside area, and samples are pumped to gas analyzers. These are in the bypass system, that is, all are interconnected, allowing the passage of a single sample through all the analyzers. The gas analyzers used in this experiment come from the company SABLE SYSTEMS®, with the following models being used: TA-1B O<sup>2</sup> analyzer, CA-2A CO2 analyzer, and MA-1 CH<sup>4</sup> analyzer.

Gas reading in the analyzers occurs in 5 min cycles. At the beginning of each cycle, the circuit is automatically moved by the equipment to a piping, which is connected to an outside area outside and an air sample is collected. The external air sample (atmospheric), called "baseline," circulates throughout the circuit until the gaseous material is analyzed. The system is then shifted to a closed sampling loop and the air is sampled from the chamber interior and analyzed. The baseline and the gas sample pass continuously through the system for 5 min. The data reading occurs in the last 30 s (the first 4 min 30 s were for ensuring that there were no residuals from the samples). Animal oxygen consumption, methane, and carbon dioxide production are calculated by the difference between external air concentrations and the chamber air. Due to the gaseous nature of the material, the control of temperature, pressure, and humidity of the system is very important, since these factors are responsible for changes in the volumes of each gas evaluated in relation to the temperature and pressure normal conditions. The chamber is constructed of steel and has two opposing openings, one that allows the entrance and exit of the animal (larger door, 2 m length and 2.2 m height) and one for feeding, with minimum air displacement, in the front part, with an area of 0.75 m<sup>2</sup> (1 m long and 0.75 m high). On the sides, there are acrylic windows, sealed, which allow the visualization of the animal and the interior of the chamber, as well as another animal, placed parallel to the chamber, in a cage. The internal volume of the camera is 22.391 L.

Due to the complexity of this system, it is necessary to determine a correction factor for the whole system [9], in order to have a correlation between reading and actual gas concentrations.

## **4. Daily analyzer calibration**

Heat production

174 Animal Husbandry and Nutrition

of the sampled gas.

Norberto Mário Rodriguez.

CH4

where HP is the heat production; O<sup>2</sup>

volume, L; N is the urinary nitrogen.

**3. Open circuit respirometry system**

*HP* = (3.866 × *O*2) + (1.2 × *CO*2) − (0.518 × *CH*4) − (1.431 × *N*) (1)

The food, feces, and urine crude energy are determined by caloric pump. Brouwer's equation allows the calculation of heat production by an animal, after evaluation of produced gases over time. A range of possibilities open up in the study of energy metabolism of animals,

LAMACA's respirometric chambers operate in open circuit system (**Figure 2**). The animal is housed in a chamber with a sealing that does not allow any gas exchange with the outside air, except by a proper air circulation system. Air tubing is coupled to a pump, which performs the renewal of air inside the chamber in a constant flow during the measurement, regulated by a mass flow meter, which corrects the airflow as a function of temperature, pressure, and humidity. According to [8], the flow control system represents a major limitation of this method, since the accuracy of this measurement is indispensable for the proper functioning of the system.

The air inside the chamber is continuously renewed by the constant input of external air. The input of fresh air into the chamber is possible due to the negative pressure created by the pump that promotes the suction of the internal air, thus allowing the entrance of external air. There is a renewal of the inside air that can be used for sampling and later evaluation by the gas analyzers. The internal negative pressure guarantees safety in the data acquisition because it prevents leakage of the air, which could constitute a source of errors in the analysis

**Figure 2.** Respirometric chambers for large animal (left) and small animal (right), presented by its designer, professor

volume, L; CO2

is the CO2

volume, L; CH4

is the

is the O2

including food assessment and determination of nutrient requirements.

Gas analyzer calibration shall be performed whenever the equipment is used. Gases are injected in a constant flow and known concentrations. After stabilization, the read value is an adjustment to the actual value. Pure nitrogen is used to calibrate the analyzer for zero concentration, while atmospheric air is used to calibrate the O2 , CO2 , and methane analyzers. Atmospheric air O2 concentration is 20.946%. The CO<sup>2</sup> and CH4 have a known concentration because they are diluted in nitrogen (5 and 1%, respectively). Stabilization is inversely proportional to the gas aliquot directed to the devices. LAMACA uses 0.2 L/min flow [10], which requires approximately 5 min for values stabilization.

Atmospheric air or standard gas (21% diluted O<sup>2</sup> in nitrogen) were evaluated to carry out the O2 analyzer calibration. The results for methane, carbon dioxide production, and oxygen consumption, as well as the animal heat production, were compared. All tests had best results with atmospheric air; then, we chose it for all analyses, with O2 air concentration as constant.

## **5. Correct factor determination**

Before starting any work, a correct factor must be determined to eliminate CO2 and O2 concentration effect, according to [8]. To determine the correction factors, the first activity to be performed is to check the chamber's sealing conditions, ensuring that no air is exchanged with the outside, except by the pump system.

After the injection flow determination, the manometers are assembled to the cylinders that are weighted in a 0.1 g accuracy balance. After this, all the cylinders are connected to the chamber by specific piping. Each one contains a flow meter for injection flows determination. The calibration process is started. When all the analyzers are calibrated, the readings are started. Desired injection flow for each gas is reached after the first reading cycle. The used injection time is approximately 4 h. The cylinder registers are closed and temperature and pressure inside the chamber are recorded hourly, after gas injection time is completed. All cylinders are weighed again. The cylinders with water condensation should be weighed the next day. After the initial and final cylinders weighing, we know how much gas was injected (g). One mole of any gas has 22.4 liters volume in normal temperature and pressure conditions. Each injected gas volume (L) can be calculated by dividing the weight (g) of the injected values of 1.2506,

injection process. At the beginning of the injection, gas concentration will increase. At the

The first point for measuring injected volumes of each gas by the analyzer is the determination of the initial, final, and average concentrations of methane, carbon dioxide, and oxygen in atmospheric air and in the air leaving the chamber. The air volume present inside the humidity-free chamber and in normal conditions is determined. Dry air volume in the initial normal conditions (Vsi) and the dry air volume in final normal conditions (Vsf), according to

where Vs is the dry air size inside the chamber at normal conditions in the beginning or by the end of measurement (L); V is the inside chamber size; T is the beginning or end temperature

<sup>+</sup> *<sup>V</sup>*CO2*<sup>i</sup>*

concentration in air leaving the chamber (%); Vt is the total size in air through in the system (flow L × minutes); Ce is the gas average concentration at atmospheric air that is entering the

Cf is the gas final concentration at last reading (%); Vsf is the gas final size inside chamber

<sup>+</sup> *<sup>V</sup>*N2*<sup>i</sup>*

is the injected CO<sup>2</sup>

concentration inside the chamber after the complete

concentration stabilizes at minimum values.

stabilization is considered for the correction

O)/760) (4)

<sup>O</sup> is the beginning or end

was calculated according

is the injected N<sup>2</sup>

(L);

)]} <sup>+</sup> {[*Cf* <sup>×</sup> *Vsf*/100]–[*Ci* <sup>×</sup> *Vsi*/100]}] (5)

; Vinj is the injected gas size (L); Cs is the average gas

(L); VN2i

value starts to

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 177

1.9647, and 0.7162, respectively, for nitrogen, carbon dioxide, and methane.

end of the injection, gas concentration reaches maximum value. Then, the CO<sup>2</sup>

*VSi or Vsf* <sup>=</sup> (*VC*) <sup>×</sup> (273/(<sup>273</sup> <sup>+</sup> *<sup>T</sup>*)) <sup>×</sup> ((*<sup>P</sup>* <sup>−</sup> *<sup>P</sup>*H2

(°C); P is the beginning or end environment pressure (mmHg); PH2

partial pressure (mmHg); the correction factor for methane and CO2

(*Ce*/100) ×[*Vt*–(*V*CH4*<sup>i</sup>*

or CO2

(L); VCO2i

{

is the injected CH<sup>4</sup>

The next step is the evaluation of CO2

factor calculation.

Vsi and Vsf

to Eq. (4).

and CO2

chamber (%); VCH4i

correct factor.

*<sup>F</sup>* <sup>=</sup> (*Vinj*)/[(*Cs* <sup>×</sup> *Vt*/100)–

where F is the correct factor for CH4

CH4

[9], are calculated as follows:

reduce. Further values are discarded after CO2

Time from the beginning of gas injection and CO<sup>2</sup>

The correct factor determination and use of the large animal chamber at LAMACA is described here. In this system, the pump that performs the air renewal was later allocated to the chamber generating a slight pressure inside the chamber, so that the external environment is well ventilated.

A negative pressure will be generated inside the chamber, which can be verified using a differential column manometer. This should be connected one point to the chamber at the endpoint and the other at an outside point. After a short time of operation of the flow, a gap can be seen between the two columns, indicating a considerable resistance for the external air to enter the chamber through another path than the pipe itself for its renewal. The total displacement of the water column (WC) is given by the sum of the elevation (*E*) of this on the side connected to the chamber and the lowering (L) on the side open to the environment. Usually, in a well-planned system, this total displacement reaches 0.5 cm.

After verification of the system seal, the quantity of each injected gas is calculated. The gases used were CH4 , CO2 , and N2 , with purity higher than 99.99%. These three gases were injected simultaneously, and the injection of methane and carbon dioxide resulted in an increase in their concentration inside the chamber, simulating what happens when the animal is housed. In turn, nitrogen injection resulted in all gases dilution, such as oxygen, which was reduced inside the chamber simulating the consumption by the animal. An important point of this step is determining the injected gas flow and air renewal flow. The determination of these values considers the achieved standard value. The established value was 200 L/min. Injected flow used for each gas (CH4 , CO2 , and N2 ) aim to reach 0.04, 0.50, and 20.50% to CH<sup>4</sup> , CO2 , and O2 , respectively. Calculations are as follows:

Methane and carbon dioxide flow

$$Fi = \left( (\Box d \times Fr) - (\Box a \times Fr) \right) / \left( \mathbb{P} / 100 \right) \tag{2}$$

where Fi is the injection flow (L/min); Cd is the desired gas concentration (%); Fr is the renewed air flow used (L/min); Ca is the atmospheric air concentration (%); P is the gas purity (%).

Nitrogen flow

$$\text{Fi} = \left( \left( \left( \text{Ca}\,\text{O}\_2 \times \text{Fr} \right) / \text{Cd}\,\text{O}\_2 \right) - \text{Fr} \right) / \left( \text{P} / 100 \right) \tag{3}$$

where Fi is the injection flow (L/min); CaO<sup>2</sup> is the oxygen atmospheric concentration (%); CdO2 is the oxygen concentration desired (%); Fr is the renewed air flow used (L/min); P is the gas purity (%).

After the injection flow determination, the manometers are assembled to the cylinders that are weighted in a 0.1 g accuracy balance. After this, all the cylinders are connected to the chamber by specific piping. Each one contains a flow meter for injection flows determination. The calibration process is started. When all the analyzers are calibrated, the readings are started. Desired injection flow for each gas is reached after the first reading cycle. The used injection time is approximately 4 h. The cylinder registers are closed and temperature and pressure inside the chamber are recorded hourly, after gas injection time is completed. All cylinders are weighed again. The cylinders with water condensation should be weighed the next day. After the initial and final cylinders weighing, we know how much gas was injected (g). One mole of any gas has 22.4 liters volume in normal temperature and pressure conditions. Each injected gas volume (L) can be calculated by dividing the weight (g) of the injected values of 1.2506, 1.9647, and 0.7162, respectively, for nitrogen, carbon dioxide, and methane.

The next step is the evaluation of CO2 concentration inside the chamber after the complete injection process. At the beginning of the injection, gas concentration will increase. At the end of the injection, gas concentration reaches maximum value. Then, the CO<sup>2</sup> value starts to reduce. Further values are discarded after CO2 concentration stabilizes at minimum values. Time from the beginning of gas injection and CO<sup>2</sup> stabilization is considered for the correction factor calculation.

The first point for measuring injected volumes of each gas by the analyzer is the determination of the initial, final, and average concentrations of methane, carbon dioxide, and oxygen in atmospheric air and in the air leaving the chamber. The air volume present inside the humidity-free chamber and in normal conditions is determined. Dry air volume in the initial normal conditions (Vsi) and the dry air volume in final normal conditions (Vsf), according to [9], are calculated as follows:

Vsi and Vsf

**5. Correct factor determination**

is well ventilated.

176 Animal Husbandry and Nutrition

used were CH4

used for each gas (CH4

Nitrogen flow

the gas purity (%).

CdO2

, CO2

, and N2

, CO2

respectively. Calculations are as follows:

where Fi is the injection flow (L/min); CaO<sup>2</sup>

Methane and carbon dioxide flow

with the outside, except by the pump system.

in a well-planned system, this total displacement reaches 0.5 cm.

, and N2

Before starting any work, a correct factor must be determined to eliminate CO2

centration effect, according to [8]. To determine the correction factors, the first activity to be performed is to check the chamber's sealing conditions, ensuring that no air is exchanged

The correct factor determination and use of the large animal chamber at LAMACA is described here. In this system, the pump that performs the air renewal was later allocated to the chamber generating a slight pressure inside the chamber, so that the external environment

A negative pressure will be generated inside the chamber, which can be verified using a differential column manometer. This should be connected one point to the chamber at the endpoint and the other at an outside point. After a short time of operation of the flow, a gap can be seen between the two columns, indicating a considerable resistance for the external air to enter the chamber through another path than the pipe itself for its renewal. The total displacement of the water column (WC) is given by the sum of the elevation (*E*) of this on the side connected to the chamber and the lowering (L) on the side open to the environment. Usually,

After verification of the system seal, the quantity of each injected gas is calculated. The gases

simultaneously, and the injection of methane and carbon dioxide resulted in an increase in their concentration inside the chamber, simulating what happens when the animal is housed. In turn, nitrogen injection resulted in all gases dilution, such as oxygen, which was reduced inside the chamber simulating the consumption by the animal. An important point of this step is determining the injected gas flow and air renewal flow. The determination of these values considers the achieved standard value. The established value was 200 L/min. Injected flow

*Fi* = ((*Cd* × *Fr*) − (*Ca* × *Fr*))/(*P*/100) (2)

where Fi is the injection flow (L/min); Cd is the desired gas concentration (%); Fr is the renewed air flow used (L/min); Ca is the atmospheric air concentration (%); P is the gas purity (%).

*Fi* = (((*Ca O*<sup>2</sup> × *Fr*)/*Cd O*2) − *Fr*)/(*P*/100) (3)

is the oxygen concentration desired (%); Fr is the renewed air flow used (L/min); P is

, with purity higher than 99.99%. These three gases were injected

) aim to reach 0.04, 0.50, and 20.50% to CH<sup>4</sup>

is the oxygen atmospheric concentration (%);

and O2

, CO2

, and O2 ,

con-

$$\text{VSi or Vsf} = \text{(VCi} \times \text{(273/(273 + T))} \times \left( (P - P\_{H\_2O}) / 760 \right) \tag{4}$$

where Vs is the dry air size inside the chamber at normal conditions in the beginning or by the end of measurement (L); V is the inside chamber size; T is the beginning or end temperature (°C); P is the beginning or end environment pressure (mmHg); PH2 <sup>O</sup> is the beginning or end partial pressure (mmHg); the correction factor for methane and CO2 was calculated according to Eq. (4).

CH4 and CO2 correct factor.

$$F = (V\_{\rm inj}) / \left[ \text{(Cs} \times \text{Vt} / 100 \text{)} - \left\{ \text{(Ce/100)} \times \left[ \text{Vt} - \left( V\_{\text{CH}\_4} + V\_{\text{CO}\_3} + V\_{\text{N}\_3} \right) \right] \right\} + \left\{ \left[ \text{C} \circ \text{V} \circ \text{V} \circ \text{100} \right] - \left[ \text{Ci} \times \text{Vsi} / 100 \right] \right\} \right] \tag{5}$$

where F is the correct factor for CH4 or CO2 ; Vinj is the injected gas size (L); Cs is the average gas concentration in air leaving the chamber (%); Vt is the total size in air through in the system (flow L × minutes); Ce is the gas average concentration at atmospheric air that is entering the chamber (%); VCH4i is the injected CH<sup>4</sup> (L); VCO2i is the injected CO<sup>2</sup> (L); VN2i is the injected N<sup>2</sup> (L); Cf is the gas final concentration at last reading (%); Vsf is the gas final size inside chamber corrected for normal conditions (L); Ci is the gas initial concentration at first reading (%); Vsi is the initial air size in chamber corrected for normal conditions (L).

Then, the calculations are performed to determine the correction factor for oxygen. The oxygen correction factor is a function of the carbon dioxide concentration (FO2 × CO2 ). In the analysis systems used—paramagnetic sensor for oxygen and infrared for methane and carbon dioxide—there is interference of the concentration of CO2 in the reading of O2 concentration (Eq. 6). A gas mixture containing known CO2 , O2 , and N2 concentrations has its concentrations measured several times in normal conditions and with the use of the CO2 absorber, located before the analyzers. Several repetitions are observed with the CO<sup>2</sup> concentrations, so the effect of CO2 (present or not) on O2 concentration (with and without the use of absorber) can be known.

O2 and CO2 correction factor

$$\text{FO}\_2 \times \text{CO}\_2 = \left\langle \text{CO}\_2 \, ab - \text{CO}\_2 \, ab \right\rangle / \text{C}\_{\text{CO}\_2} \tag{6}$$

monitoring of blood parameters that may indicate if something is wrong. Zebu and their crossbreeds—the focus of our research line—are more temperamental than taurine animals. Sometimes, they get angry and they always stay alert to external movements and sounds. The training we adopt is based on the principles of rational taming [10]. All animals are gradually presented to the experimental conditions that they will be subjected to. isolation, pain, sudden noise or fear situations make them stressed and should be avoided. Observation is done on each individual animal, and daily behavior is assessed as experimentation methodologies are introduced. Daily baths and brushings are used; and there is daily contact with undergraduate and graduate students, teachers and employees (**Figure 3**), always with a lot of care and patience. The basic principles are respect and communication in a language that the animal can understand. Fear, intimidation, or pain is never used. Nelore, Guzerá, Gyr and F1 – Holstein × Gyr animals were very afraid at the beginning of the work, but when they were presented to daily management, facilities and devices, they became calm and quiet.

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 179

**Figure 3.** Animals used in experiments during rational taming (source: Personal archive).

An apparent digestibility assay is performed immediately before every measurement in the respirometry chamber. Total stool is collected for 5 days and urine for 24 h. Then, the animal is confined for 24 h in the respirometry chamber. Temperature, pressure, and humidity are constant, with an automatic air conditioning. This way, the chamber is subjected to a continuous

**7. Experimental routine**

where FO2 × CO2 is the O2 correction factor in function of CO2 ; CO2 ab is the O2 concentration with absorber (%); CO2 sab is the O2 concentration without absorber (%); CCO2 is the CO2 concentration utilized (%).

Eq. 7 determines the correct factor for oxygen.

$$\begin{array}{rcl} F = \left( \left( \text{C}a/100 \right) \times \text{Vt} - \left( V\_{\text{CH}\_2} + \text{VCO}\_2 \text{O}\_2 \text{ i} + V\_{\text{N}\_2} \right) \right) - \left( \left( \left( \text{C}f + \text{FO}\_2 \text{O}\_2 \text{i} \right) \right) \times \text{Vst} \right) \\ \times \text{CO}\_2 \times \text{CfCO}\_2 \text{j} \right) / 100 - \left( \left( \text{Ci} + \left( \text{FO}\_2 \times \text{CO}\_2 \times \text{iCCO}\_2 \text{j} \right) \right) \times \text{Vst} \right) / 100 \end{array}$$

where F is the O2 correction factor; Ca is the O2 average concentration at atmospheric air coming inside the chamber (%); Vt is the air total size through the system (flow, L × min); VCH4i is the CH4 (L) injected; VCO2i is the CO2 (L) injected; VN2i is the N2 (L) injected; Cf is the O<sup>2</sup> final concentration, at last reading (%); FO<sup>2</sup> × CO2 is the O2 concentration correct factor in function of CO2 ; CfCO2 is the CO2 final concentration, at last reading (%); Vsf is the chamber air size correction for normal conditions (L); Ci is the O2 initial concentration, at first reading (%); CiCO2 is the CO2 initial concentration, at first reading (%); Vsi is the chamber air initial size correction for normal conditions (L).

#### **6. Animal adaptation and taming**

After system calibration, measures can begin. Small ruminant respirometric chambers methodology in LAMACA was published by [9]. Working with bovines, the system calibration process is hard since the chamber is big and so air circulation is complicated. Besides this, the species peculiarities have showed us that the adaption period must be longer, until the animal appears so calm that its behavior is similar inside and outside of the chamber. Since 2008, when investigations with bovines began on this lab, procedures have been adopted in order to get a similar inside and outside chamber dry matter intake, under normal conditions. This work is based on animal welfare assurance, with animal behavioral assessments and

**Figure 3.** Animals used in experiments during rational taming (source: Personal archive).

monitoring of blood parameters that may indicate if something is wrong. Zebu and their crossbreeds—the focus of our research line—are more temperamental than taurine animals. Sometimes, they get angry and they always stay alert to external movements and sounds. The training we adopt is based on the principles of rational taming [10]. All animals are gradually presented to the experimental conditions that they will be subjected to. isolation, pain, sudden noise or fear situations make them stressed and should be avoided. Observation is done on each individual animal, and daily behavior is assessed as experimentation methodologies are introduced. Daily baths and brushings are used; and there is daily contact with undergraduate and graduate students, teachers and employees (**Figure 3**), always with a lot of care and patience. The basic principles are respect and communication in a language that the animal can understand. Fear, intimidation, or pain is never used. Nelore, Guzerá, Gyr and F1 – Holstein × Gyr animals were very afraid at the beginning of the work, but when they were presented to daily management, facilities and devices, they became calm and quiet.

## **7. Experimental routine**

corrected for normal conditions (L); Ci is the gas initial concentration at first reading (%); Vsi

Then, the calculations are performed to determine the correction factor for oxygen. The oxygen

systems used—paramagnetic sensor for oxygen and infrared for methane and carbon diox-

, and N2

correction factor in function of CO2

ing inside the chamber (%); Vt is the air total size through the system (flow, L × min); VCH4i

(L) injected; VN2i

After system calibration, measures can begin. Small ruminant respirometric chambers methodology in LAMACA was published by [9]. Working with bovines, the system calibration process is hard since the chamber is big and so air circulation is complicated. Besides this, the species peculiarities have showed us that the adaption period must be longer, until the animal appears so calm that its behavior is similar inside and outside of the chamber. Since 2008, when investigations with bovines began on this lab, procedures have been adopted in order to get a similar inside and outside chamber dry matter intake, under normal conditions. This work is based on animal welfare assurance, with animal behavioral assessments and

is the O2

in the reading of O2

concentration (with and without the use of absorber) can be known.

concentration without absorber (%); CCO2

× *CO*<sup>2</sup> × *CfCO*2)) × *Vsf*)/100 − ((*Ci* + (*FO*<sup>2</sup> × *CO*<sup>2</sup> × *CiCO*2)) × *Vsi*)/100) (7)

initial concentration, at first reading (%); Vsi is the chamber air initial size

is the N2

final concentration, at last reading (%); Vsf is the chamber air size

+ *VCO*<sup>2</sup> *O*<sup>2</sup> *i* + *VN*2*<sup>i</sup>*

concentrations has its concentrations mea-

; CO2 ab is the O2

))) − (((*Cf* + (*FO*<sup>2</sup>

average concentration at atmospheric air com-

(L) injected; Cf is the O<sup>2</sup>

concentration correct factor in function

initial concentration, at first reading (%);

). In the analysis

(6)

con-

is

final

concentration

is the CO2

concentration (Eq. 6).

absorber, located before

concentrations, so the effect of

is the initial air size in chamber corrected for normal conditions (L).

sured several times in normal conditions and with the use of the CO2

the analyzers. Several repetitions are observed with the CO<sup>2</sup>

*FO*<sup>2</sup> × *CO*<sup>2</sup> = (*CO*<sup>2</sup> *ab* − *CO*<sup>2</sup> *sab*)/*CCO*<sup>2</sup>

correction factor; Ca is the O2

ide—there is interference of the concentration of CO2

A gas mixture containing known CO2

correction factor

is the O2

Eq. 7 determines the correct factor for oxygen.

*<sup>F</sup>* <sup>=</sup> ((*Ca*/100) <sup>×</sup> *Vt* <sup>−</sup> (*VCH*4*<sup>i</sup>*

(L) injected; VCO2i is the CO2

concentration, at last reading (%); FO<sup>2</sup> × CO2

correction for normal conditions (L); Ci is the O2

is the CO2

correction for normal conditions (L).

**6. Animal adaptation and taming**

with absorber (%); CO2 sab is the O2

(present or not) on O2

CO2

O2

and CO2

178 Animal Husbandry and Nutrition

where FO2 × CO2

where F is the O2

; CfCO2

is the CO2

the CH4

of CO2

CiCO2

centration utilized (%).

correction factor is a function of the carbon dioxide concentration (FO2 × CO2

, O2

An apparent digestibility assay is performed immediately before every measurement in the respirometry chamber. Total stool is collected for 5 days and urine for 24 h. Then, the animal is confined for 24 h in the respirometry chamber. Temperature, pressure, and humidity are constant, with an automatic air conditioning. This way, the chamber is subjected to a continuous flow of air so that the inlet points of the atmospheric air and the internal air outlet of the chamber are located on opposite sides. This results in a constant renewal of internal air, avoiding CO2 concentration greater than 1% [11], cited by [9]. During the 24 h of measurements, analyzers (Sable brand) monitor carbon dioxide, oxygen, and methane concentrations every 5 min, alternately. Total air circulating throughout the chamber, air flow (in L/min) used, multiplied by the total measurement time (min) gives gas quantities entering and leaving the chamber. Therefore, by difference, carbon dioxide and methane output and consumed oxygen are used to determine animal heat production. The analyzers used in these experiments require a daily calibration to ensure read reliability. Calibration consists of adjusting the analyzer reading at the end of each 5 min cycle for each gas concentration range. At the end of each cycle, analyzers of each gas shows gas concentration similar to the cylinder concentration. In the CO2 case, the concentration should range from 4.990 to 5.007 and for CH<sup>4</sup> , the allowed range is from 0.997 to 1.003. In the case of N<sup>2</sup> , all devices must have close to zero values with at least two decimal places. They can differ from each other only in the third decimal. For O<sup>2</sup> , the reading indicated by the analyzer should be between 20.9450 and 20.9510. If the analyzers have performed right readings after three rounds (each round corresponds to the four 5 min cycles for each gas—N2 , CO2 , CH4 , and O2 ) without adjustments, the equipment is calibrated.

we stop readings and the animal is removed from the chamber. Sorts are weighed. Knowing dry matter intake inside the chamber allows the calculation of the caloric increment required for energy partition. It is essential that the animals maintain the feed intake observed in the

The second measurement is with a fasting animal. The animal is placed in the chamber after 48 h of fasting solid food and staying there until the next day (72 h). Water must be *ad libitum*

Gross energy intake and feces gross energy are determined in an adiabatic calorimetric pump for digestible energy calculation. Metabolizable energy is calculated considering urine and methane. The quantification of energy losses in the form of methane will be done in the respirometric chamber. For each liter of methane, a value corresponding to 9.47 kcal should be attributed [7]. The metabolizability (q) of the diet will be calculated by the relation between metabolizable energy and gross energy ingested [7]. The efficiency of using metabolizable

In one study with cross-breed milk cattle, [12] evaluated heat production in fasting bulls fed different diets corresponding to 1, 1.5, and 2 times (1×, 1.5×, and 2×) the dry matter intake (DMI)

differ between animals at 1× and 1.5× the maintenance diet, providing mean values of 22.25

higher production (*P* < 0.001) than the animals in the 1× group, under fasted and fed conditions. Fasting heat production (FHP) was greater (*P* < 0.001) for the two × group (133.3 kcal/kg LW0.75), compared with the other groups (112.1 and 107.9 kcal/kg LW0.75, respectively), among

occurred with reduced intake are in line with the results obtained by [13], who indicated that the rates of oxygen consumption by organs like the liver and kidneys, per gram of tissue or as a function of their mass, decreased in response to feeding at the maintenance level. The effect of diet on maintenance metabolism has been associated with variations in the tissue metabolic rate. The causes of these variations are associated with changes in the energy rates and costs of blood flow, of the entrance of oxygen into the liver and in nutrient transference

A linear increase (*P* < 0.001) in FHP was seen in the present study with increased intake of DM. The highest values of FHP found, for the highest levels of feeding, reflect the increase in energy demands as a function of the productive condition of the animal. Calculating how much of this increase is due to the maintenance or weight-gain diet becomes an issue of

and 39.03 L/kg PV0.75 for the animals under fasted and fed conditions, respectively. CO2

, and *k*p) is the relation between the net energy and

consumption and CO2

consumption as a function of

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 181

produc-

production that

consumption with values of 26.77

consumption (L/kg LW0.75) under fasted and fed conditions did not

consumption, was greater for the 2× animals, which showed 21.2% and 37.6%

**9. Energy partition, net energy requirement, and energy efficiency**

, *k*l

and 30.35 L/kg LW0.75, which represented a 36.4% increase in O<sup>2</sup>

eating. The 2× treatment provided the greatest (*P* < 0.001) O<sup>2</sup>

those in which the FHP did not differ. The lowest O<sup>2</sup>

apparent digestibility assay.

energy for different functions (*k*m, *k*<sup>g</sup>

metabolizable energy.

tion, similar to O2

for weight maintenance. O2

in the intestinal lumen [14].

all the time.

Measurements start immediately after calibration. Mass flowmeter flow is adjusted according to the animal's live weight, as well as after ensuring air circulation and cooling systems are operating normally. Residual gas present inside the chamber must be added to the total volume of produced gases (carbon and methane) and consumed oxygen. Vsi and Vsf are determined by discounting animal volume multiplied by gases concentration at the beginning and at the end of the measurement, respectively. By subtracting the final and initial values, gas accumulated in the chamber (for carbon and methane) and consumed oxygen are obtained. These values are added to the values obtained previously, resulting in the final values of produced carbon dioxide, methane, and consumed oxygen, which are used to determine the animal heat production. Heat production measurements are carried out with fed animals at production levels in accordance with the established treatment (weight maintenance, intermediate and *ad libitum*), at the various physiological stages or after 48-h solid food fasting. The difference between the values of fed and fasting animal will be the caloric increment. Diet net and metabolizable energy content can be found [4].

Fasting heat production (FHP, kcal) corresponds to net energy requirements for maintenance. In the fed animal, it corresponds to the sum of the energy necessary for maintenance plus the caloric increment of feed consumed. PC is calculated by using an equation (Eq. 1) of [7]. Some authors mention high values for the estimation of the NEm requirement from heat production in fasting.

### **8. Chamber measurements**

At the first time, the animals pass through the chamber receiving the same diet provided in the digestibility assay. The power supply must only be provided when the equipment is ready to start reading. The chamber door will be closed and the reading will begin. Next day, we stop readings and the animal is removed from the chamber. Sorts are weighed. Knowing dry matter intake inside the chamber allows the calculation of the caloric increment required for energy partition. It is essential that the animals maintain the feed intake observed in the apparent digestibility assay.

The second measurement is with a fasting animal. The animal is placed in the chamber after 48 h of fasting solid food and staying there until the next day (72 h). Water must be *ad libitum* all the time.

## **9. Energy partition, net energy requirement, and energy efficiency**

flow of air so that the inlet points of the atmospheric air and the internal air outlet of the chamber are located on opposite sides. This results in a constant renewal of internal air, avoiding

the concentration should range from 4.990 to 5.007 and for CH<sup>4</sup>

decimal places. They can differ from each other only in the third decimal. For O<sup>2</sup>

indicated by the analyzer should be between 20.9450 and 20.9510. If the analyzers have performed right readings after three rounds (each round corresponds to the four 5 min cycles for

Measurements start immediately after calibration. Mass flowmeter flow is adjusted according to the animal's live weight, as well as after ensuring air circulation and cooling systems are operating normally. Residual gas present inside the chamber must be added to the total volume of produced gases (carbon and methane) and consumed oxygen. Vsi and Vsf are determined by discounting animal volume multiplied by gases concentration at the beginning and at the end of the measurement, respectively. By subtracting the final and initial values, gas accumulated in the chamber (for carbon and methane) and consumed oxygen are obtained. These values are added to the values obtained previously, resulting in the final values of produced carbon dioxide, methane, and consumed oxygen, which are used to determine the animal heat production. Heat production measurements are carried out with fed animals at production levels in accordance with the established treatment (weight maintenance, intermediate and *ad libitum*), at the various physiological stages or after 48-h solid food fasting. The difference between the values of fed and fasting animal will be the caloric increment. Diet net

Fasting heat production (FHP, kcal) corresponds to net energy requirements for maintenance. In the fed animal, it corresponds to the sum of the energy necessary for maintenance plus the caloric increment of feed consumed. PC is calculated by using an equation (Eq. 1) of [7]. Some authors mention high values for the estimation of the NEm requirement from heat production

At the first time, the animals pass through the chamber receiving the same diet provided in the digestibility assay. The power supply must only be provided when the equipment is ready to start reading. The chamber door will be closed and the reading will begin. Next day,

0.997 to 1.003. In the case of N<sup>2</sup>

, CO2

, CH4

, and O2

and metabolizable energy content can be found [4].

each gas—N2

in fasting.

**8. Chamber measurements**

 concentration greater than 1% [11], cited by [9]. During the 24 h of measurements, analyzers (Sable brand) monitor carbon dioxide, oxygen, and methane concentrations every 5 min, alternately. Total air circulating throughout the chamber, air flow (in L/min) used, multiplied by the total measurement time (min) gives gas quantities entering and leaving the chamber. Therefore, by difference, carbon dioxide and methane output and consumed oxygen are used to determine animal heat production. The analyzers used in these experiments require a daily calibration to ensure read reliability. Calibration consists of adjusting the analyzer reading at the end of each 5 min cycle for each gas concentration range. At the end of each cycle, analyzers of each gas shows gas concentration similar to the cylinder concentration. In the CO2

case,

, the reading

, the allowed range is from

, all devices must have close to zero values with at least two

) without adjustments, the equipment is calibrated.

CO2

180 Animal Husbandry and Nutrition

Gross energy intake and feces gross energy are determined in an adiabatic calorimetric pump for digestible energy calculation. Metabolizable energy is calculated considering urine and methane. The quantification of energy losses in the form of methane will be done in the respirometric chamber. For each liter of methane, a value corresponding to 9.47 kcal should be attributed [7]. The metabolizability (q) of the diet will be calculated by the relation between metabolizable energy and gross energy ingested [7]. The efficiency of using metabolizable energy for different functions (*k*m, *k*<sup>g</sup> , *k*l , and *k*p) is the relation between the net energy and metabolizable energy.

In one study with cross-breed milk cattle, [12] evaluated heat production in fasting bulls fed different diets corresponding to 1, 1.5, and 2 times (1×, 1.5×, and 2×) the dry matter intake (DMI) for weight maintenance. O2 consumption (L/kg LW0.75) under fasted and fed conditions did not differ between animals at 1× and 1.5× the maintenance diet, providing mean values of 22.25 and 30.35 L/kg LW0.75, which represented a 36.4% increase in O<sup>2</sup> consumption as a function of eating. The 2× treatment provided the greatest (*P* < 0.001) O<sup>2</sup> consumption with values of 26.77 and 39.03 L/kg PV0.75 for the animals under fasted and fed conditions, respectively. CO2 production, similar to O2 consumption, was greater for the 2× animals, which showed 21.2% and 37.6% higher production (*P* < 0.001) than the animals in the 1× group, under fasted and fed conditions.

Fasting heat production (FHP) was greater (*P* < 0.001) for the two × group (133.3 kcal/kg LW0.75), compared with the other groups (112.1 and 107.9 kcal/kg LW0.75, respectively), among those in which the FHP did not differ. The lowest O<sup>2</sup> consumption and CO2 production that occurred with reduced intake are in line with the results obtained by [13], who indicated that the rates of oxygen consumption by organs like the liver and kidneys, per gram of tissue or as a function of their mass, decreased in response to feeding at the maintenance level. The effect of diet on maintenance metabolism has been associated with variations in the tissue metabolic rate. The causes of these variations are associated with changes in the energy rates and costs of blood flow, of the entrance of oxygen into the liver and in nutrient transference in the intestinal lumen [14].

A linear increase (*P* < 0.001) in FHP was seen in the present study with increased intake of DM. The highest values of FHP found, for the highest levels of feeding, reflect the increase in energy demands as a function of the productive condition of the animal. Calculating how much of this increase is due to the maintenance or weight-gain diet becomes an issue of semantics, as [15] reports, as the curvilinear relationship between retained energy and food intake may be explained by considering a decrease in the efficiency of use of the food supplied above the constant maintenance level. It may also be explained by considering a constant efficiency and a progressive increase in the components analogous to the maintenance diet.

**11. Energy efficiency use: relationship between metabolizable and** 

are used for growth and weight gain, *k*<sup>l</sup>

**12. Some results obtained with respirometry**

of metabolizable energy for gain (*k*<sup>g</sup>

From energy partition in the animal, we can obtain values that indicate the efficiency of the animal in using the energy for maintenance and/or production. The terms that make this evaluation possible are known as the metabolizability (q) and energy efficiency of use (*k*). [7] defines "q" (the quality factor) as the portion of metabolizable energy contained in the gross energy ingested, and the constant "*k*", as the portion of the metabolizable energy retained as net energy directed to maintenance, weight gain, fetus and fetal attachments and milk. When the animal is fed at maintenance level, the letter "m" (qm and *k*m) is added to such constants. Likewise, the

*k*m was defined by [23] cited by [5], as the linear regression slope between negative energy retention, that is, energy loss, and ingested metabolizable energy. The efficiency of the use

of the linear regression between positive retained energy and metabolizable energy intake. When evaluating the nutritional requirements through the respirometric technique, the efficiencies of retention of the metabolizable energy are calculated as a function of the relation between the retained energy, that is, net energy, and the metabolizable energy, being *k*<sup>m</sup> = 1 – (PCalimentado − PCjejum)/MEI, where MEI corresponds to the ingested metabolizable energy

The efficiency of using the metabolizable energy for maintenance is greater than that directed to the productive processes [1]. The various body functions of mammalian animals of the same species are more efficient in retention of metabolizable energy for maintenance, followed by lactation, weight gains, and reproduction functions. When comparing different species, the ruminant is known as the holder of the lowest net energy efficiency [25], which makes this field of research promising in the identification of components of the management of production systems that have a greater impact on the nutritional efficiency of these animals. It is important to determine the energy efficiency use since several factors can influence them. The variable "q", for example, changes as a function of intake levels, and there are larger fecal losses with highest intake due to a higher passage rate and potentially digestible material escape. The digestible energy can decrease from 2.1 to 6.2% as energy consumption increases in relation to the maintenance level [26]. Urine energy losses tend to be constant, as well as losses due to methane production, ranging from about 5 to 12% in urine and 3 to 5% for

Gyr, Nelore, Guzerá, Holstein, and F1 Holstein × Gyr animals (**Figure 4**) were evaluated at different physiological stages (growth, adult animal, weight gain, gestation, and lactation) and different nutritional levels (maintenance, intermediate, *ad libitum*). Animal breed, sex, and physiological state were evaluated and presented no significant effect on methane production. Dry matter intake (DMI) explained 87.7% of the variation in methane production;

for milk production and *k*<sup>f</sup>

), according to the same author, was defined as the slope

for gestation.

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 183

**net energy**

terms *k*<sup>g</sup>

[24].

methane [27].

Some author's report increased NEm values when using the FHP [16, 12] constructed the regression equation obtained by the logarithm for heat production (HP) measured in the respirometry chamber, on different diets, as a function of MEI. The values found by the extrapolation for metabolizable energy intake equal to zero corresponded to the "NE<sup>m</sup> 3 " values described in **Figure 6**. It is noted that these "NE<sup>m</sup> 3 " values are less than those obtained by the FHP (NE<sup>m</sup> 2 ) and closer to those obtained in experiments with comparative slaughter. The studies are in an initial phase and need to be expanded since they may indicate the change of methodology adopted in the experiments using respirometry. Similar to NEm, the *k*m found using the "NE<sup>m</sup> 3 " is different from the value obtained using the "NE<sup>m</sup> 2 ."

## **10. Basal metabolism and maintenance**

The metabolizable energy for maintenance is composed of two main components. The first is the basal metabolism, which corresponds to the minimum energy required to support the vital processes in a fasting healthy animal, in the post-absorptive state (48–144 h of fasting after feeding), performing the activity in the thermoneutral environment [17]. The second component associated with the requirement of metabolizable energy for maintenance involves several factors associated with the production of heat originated by the maintenance level, that is, by the heat increment, such as body temperature regulation, voluntary activity, digestion, nutrient absorption and assimilation, fermentation [19, 21].

The difference between basal metabolism and maintenance is that when in maintenance, the animal is not fasting [17]. The metabolizable energy requirement for maintenance (EMm) is defined as metabolizable energy intake (MEI), which corresponds exactly to the heat production, without any loss or gain of body reserves [19, 21]. This will occur when the retained energy equals zero (RE = 0) and the net energy for maintenance, although fundamentally important in net energy systems, cannot be directly determined by experimental techniques. So, it was stipulated that the net energy requirement for maintenance could be obtained by measuring the energy requirements of basal metabolism (EBM), which corresponds to the fasting heat production. At first, the net energy determination through the animal fasting heat production would not be appropriate, since this represents the requirements of ATP at the cellular level added to the heat produced in the formation of ATP by the mobilization of the body reserves. The most appropriate way to obtain the net energy for maintenance would be through the ratio ELm = EMB × *k*<sup>b</sup> , where *k*<sup>b</sup> is the conversion efficiency of body reserves to useful energy in the form of ATP. However, the *k*<sup>b</sup> has minimal variation (as the contribution of body reserves to ATP generation varies very little in fasting animals with similar nutritional plains), thus making the energy required for basal metabolism and fasting heat production have a strong relationship [20, 22]. This justifies the use of fasting heat production as the value adopted for net maintenance energy.

## **11. Energy efficiency use: relationship between metabolizable and net energy**

semantics, as [15] reports, as the curvilinear relationship between retained energy and food intake may be explained by considering a decrease in the efficiency of use of the food supplied above the constant maintenance level. It may also be explained by considering a constant efficiency and a progressive increase in the components analogous to the maintenance diet.

Some author's report increased NEm values when using the FHP [16, 12] constructed the regression equation obtained by the logarithm for heat production (HP) measured in the respirometry chamber, on different diets, as a function of MEI. The values found by the extrapolation for metabolizable energy intake equal to zero corresponded to the

parative slaughter. The studies are in an initial phase and need to be expanded since they may indicate the change of methodology adopted in the experiments using respirometry.

3

The metabolizable energy for maintenance is composed of two main components. The first is the basal metabolism, which corresponds to the minimum energy required to support the vital processes in a fasting healthy animal, in the post-absorptive state (48–144 h of fasting after feeding), performing the activity in the thermoneutral environment [17]. The second component associated with the requirement of metabolizable energy for maintenance involves several factors associated with the production of heat originated by the maintenance level, that is, by the heat increment, such as body temperature regulation, voluntary activity,

The difference between basal metabolism and maintenance is that when in maintenance, the animal is not fasting [17]. The metabolizable energy requirement for maintenance (EMm) is defined as metabolizable energy intake (MEI), which corresponds exactly to the heat production, without any loss or gain of body reserves [19, 21]. This will occur when the retained energy equals zero (RE = 0) and the net energy for maintenance, although fundamentally important in net energy systems, cannot be directly determined by experimental techniques. So, it was stipulated that the net energy requirement for maintenance could be obtained by measuring the energy requirements of basal metabolism (EBM), which corresponds to the fasting heat production. At first, the net energy determination through the animal fasting heat production would not be appropriate, since this represents the requirements of ATP at the cellular level added to the heat produced in the formation of ATP by the mobilization of the body reserves. The most appropriate way to obtain the net energy for maintenance would be

3

" is different from the value obtained using

is the conversion efficiency of body reserves to

has minimal variation (as the contribution

) and closer to those obtained in experiments with com-

" values are less than

" values described in **Figure 6**. It is noted that these "NE<sup>m</sup>

2

digestion, nutrient absorption and assimilation, fermentation [19, 21].

, where *k*<sup>b</sup>

of body reserves to ATP generation varies very little in fasting animals with similar nutritional plains), thus making the energy required for basal metabolism and fasting heat production have a strong relationship [20, 22]. This justifies the use of fasting heat production as the value

"NE<sup>m</sup> 3

the "NE<sup>m</sup>

2 ."

182 Animal Husbandry and Nutrition

those obtained by the FHP (NE<sup>m</sup>

through the ratio ELm = EMB × *k*<sup>b</sup>

adopted for net maintenance energy.

useful energy in the form of ATP. However, the *k*<sup>b</sup>

Similar to NEm, the *k*m found using the "NE<sup>m</sup>

**10. Basal metabolism and maintenance**

From energy partition in the animal, we can obtain values that indicate the efficiency of the animal in using the energy for maintenance and/or production. The terms that make this evaluation possible are known as the metabolizability (q) and energy efficiency of use (*k*). [7] defines "q" (the quality factor) as the portion of metabolizable energy contained in the gross energy ingested, and the constant "*k*", as the portion of the metabolizable energy retained as net energy directed to maintenance, weight gain, fetus and fetal attachments and milk. When the animal is fed at maintenance level, the letter "m" (qm and *k*m) is added to such constants. Likewise, the terms *k*<sup>g</sup> are used for growth and weight gain, *k*<sup>l</sup> for milk production and *k*<sup>f</sup> for gestation.

*k*m was defined by [23] cited by [5], as the linear regression slope between negative energy retention, that is, energy loss, and ingested metabolizable energy. The efficiency of the use of metabolizable energy for gain (*k*<sup>g</sup> ), according to the same author, was defined as the slope of the linear regression between positive retained energy and metabolizable energy intake. When evaluating the nutritional requirements through the respirometric technique, the efficiencies of retention of the metabolizable energy are calculated as a function of the relation between the retained energy, that is, net energy, and the metabolizable energy, being *k*<sup>m</sup> = 1 – (PCalimentado − PCjejum)/MEI, where MEI corresponds to the ingested metabolizable energy [24].

The efficiency of using the metabolizable energy for maintenance is greater than that directed to the productive processes [1]. The various body functions of mammalian animals of the same species are more efficient in retention of metabolizable energy for maintenance, followed by lactation, weight gains, and reproduction functions. When comparing different species, the ruminant is known as the holder of the lowest net energy efficiency [25], which makes this field of research promising in the identification of components of the management of production systems that have a greater impact on the nutritional efficiency of these animals.

It is important to determine the energy efficiency use since several factors can influence them. The variable "q", for example, changes as a function of intake levels, and there are larger fecal losses with highest intake due to a higher passage rate and potentially digestible material escape. The digestible energy can decrease from 2.1 to 6.2% as energy consumption increases in relation to the maintenance level [26]. Urine energy losses tend to be constant, as well as losses due to methane production, ranging from about 5 to 12% in urine and 3 to 5% for methane [27].

## **12. Some results obtained with respirometry**

Gyr, Nelore, Guzerá, Holstein, and F1 Holstein × Gyr animals (**Figure 4**) were evaluated at different physiological stages (growth, adult animal, weight gain, gestation, and lactation) and different nutritional levels (maintenance, intermediate, *ad libitum*). Animal breed, sex, and physiological state were evaluated and presented no significant effect on methane production. Dry matter intake (DMI) explained 87.7% of the variation in methane production;

In low-quality fodder, the addition of nutrients for microorganisms increases the efficiency of microbial growth because it increases the efficiency of the fermenting process in the rumen with a decrease in the methanogenic activity per unit of degraded carbohydrates [29]. However, there is an increase in methane production per animal ranging from 8.4 to 12.3% of

In one study with cross-bred milk cattle, [12] evaluated heat production in fasting bulls fed different diets corresponding to 1, 1.5, and 2 times (1×, 1.5×, and 2×) the DMI for weight maintenance.

consumption, was greater for the 2× animals, which showed 21.2% and 37.6% higher produc-

Fasting heat production (FHP) was greater (*P* < 0.001) for the 2× group (133.3 kcal/kg LW0.75), compared with the other groups (112.1 and 107.9 kcal/kg LW0.75, respectively), among those in

with reduced intake are in line with the results obtained by [13], who indicated that the rates of oxygen consumption by organs like the liver and kidneys, per gram of tissue or as a function of their mass, decreased in response to feeding at the maintenance level. The effect of diet on maintenance metabolism has been associated with variations in the tissue metabolic rate. The causes of these variations are associated with changes in the energy rates and costs of blood flow, of the entrance of oxygen into the liver and in nutrient transference in the intestinal lumen [14].

A linear increase (*P* < 0.001) in FHP was seen in the present study with the increased intake of DM. The highest values of FHP found, for the highest levels of feeding, reflect the increase in energy demands as a function of the productive condition of the animal. Calculating how much of this increase is due to the maintenance or weight-gain diet becomes an issue of semantics. [15] reports that the curvilinear relationship between retained energy and food intake may be explained by considering a decrease in the efficiency of use of the food supplied above maintenance level.

Some authors report increased NEm values when using the FHP. [16, 13] constructed the regression equation obtained by the logarithm for heat production (HP) measured in the res-

those obtained in experiments with comparative slaughter. The studies are in an initial phase, and need to be expanded, since they may indicate the change of methodology adopted in the

The efficiency of converting DE to ME is influenced by several factors, such as the rate of microbial growth in the rumen, production of methane, relationship between energy and protein in the diet, and efficiency of the use of metabolizable protein, among others. [15] reports that the ME/DE relationship is approximately 0.82. [14, 18] suggest a value between 0.81 and 0.80, respectively; whereas [7] uses values from 0.81 to 0.86. Higher relationships, from 0.89 to 0.92, were found by [30]. An analysis of the relationship between DE intake (DEI)

pirometry chamber, on different diets, as a function of MEI. It is noted that the "NE<sup>m</sup>

obtained by this regression are smaller than those obtained by the FHP (NE<sup>m</sup>

experiments using respirometry. Similar to the NEm, the *k*m by using the "NE<sup>m</sup>

2 ."

consumption and CO2

tion (*P* < 0.001) than the animals in the 1× group, under fasted and fed conditions.

 consumption (L/kg LW0.75) under fasted and fed conditions did not differ between animals at 1× and 1.5× the maintenance diet, providing mean values of 22.25 and 30.35 L/kg LW0.75,

consumption as a function of eating. The 2× treatment

production, similar to O2

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 185

production that occurred

3 " values

), and closer to

" is different

2

3

consumption with values of 26.77 and 39.03 L/kg PV0.75

the GEI because it is organic.

which represented a 36.4% increase in O<sup>2</sup>

which the FHP did not differ. The lowest O<sup>2</sup>

from the value obtained by using the "NE<sup>m</sup>

for the animals under fasted and fed conditions, respectively. CO2

provided the greatest (*P* < 0.001) O<sup>2</sup>

O2

**Figure 4.** F1 – Holstein × Gyr (left) and Gyr (right) heifers inside the respirometric chamber of the Metabolism and Calorimetry Laboratory of the Veterinary School of UFMG.

**Figure 5.** Relationship between daily production methane (CH<sup>4</sup> ) and dry matter intake (DMI). The points represent the evaluations considered for the development model (n = 125).

there is no improvement in the predictive model with the inclusion of other predictive variables (**Figure 5**). The same occurred with the GE intake (GEI). These data are published [1].

Several studies have shown that when animal productivity is increased, there is a reduction in the proportion of methane produced per unit of product. According to the United States' Environmental Protection Agency [28], increasing livestock productivity to achieve lower methane emissions per unit of product is the most promising and cost-effective way to reduce emissions. Moderate correlations were obtained (−0.49; *P* = 0.03) in the study by [12], showing that the level of intake relative to maintenance was inversely related to methane production. Increasing the intake by one unit above maintenance resulted in a decrease of 0.73 percentage units of methane production (%GEI).

In low-quality fodder, the addition of nutrients for microorganisms increases the efficiency of microbial growth because it increases the efficiency of the fermenting process in the rumen with a decrease in the methanogenic activity per unit of degraded carbohydrates [29]. However, there is an increase in methane production per animal ranging from 8.4 to 12.3% of the GEI because it is organic.

In one study with cross-bred milk cattle, [12] evaluated heat production in fasting bulls fed different diets corresponding to 1, 1.5, and 2 times (1×, 1.5×, and 2×) the DMI for weight maintenance. O2 consumption (L/kg LW0.75) under fasted and fed conditions did not differ between animals at 1× and 1.5× the maintenance diet, providing mean values of 22.25 and 30.35 L/kg LW0.75, which represented a 36.4% increase in O<sup>2</sup> consumption as a function of eating. The 2× treatment provided the greatest (*P* < 0.001) O<sup>2</sup> consumption with values of 26.77 and 39.03 L/kg PV0.75 for the animals under fasted and fed conditions, respectively. CO2 production, similar to O2 consumption, was greater for the 2× animals, which showed 21.2% and 37.6% higher production (*P* < 0.001) than the animals in the 1× group, under fasted and fed conditions.

Fasting heat production (FHP) was greater (*P* < 0.001) for the 2× group (133.3 kcal/kg LW0.75), compared with the other groups (112.1 and 107.9 kcal/kg LW0.75, respectively), among those in which the FHP did not differ. The lowest O<sup>2</sup> consumption and CO2 production that occurred with reduced intake are in line with the results obtained by [13], who indicated that the rates of oxygen consumption by organs like the liver and kidneys, per gram of tissue or as a function of their mass, decreased in response to feeding at the maintenance level. The effect of diet on maintenance metabolism has been associated with variations in the tissue metabolic rate. The causes of these variations are associated with changes in the energy rates and costs of blood flow, of the entrance of oxygen into the liver and in nutrient transference in the intestinal lumen [14].

A linear increase (*P* < 0.001) in FHP was seen in the present study with the increased intake of DM. The highest values of FHP found, for the highest levels of feeding, reflect the increase in energy demands as a function of the productive condition of the animal. Calculating how much of this increase is due to the maintenance or weight-gain diet becomes an issue of semantics. [15] reports that the curvilinear relationship between retained energy and food intake may be explained by considering a decrease in the efficiency of use of the food supplied above maintenance level.

Some authors report increased NEm values when using the FHP. [16, 13] constructed the regression equation obtained by the logarithm for heat production (HP) measured in the respirometry chamber, on different diets, as a function of MEI. It is noted that the "NE<sup>m</sup> 3 " values obtained by this regression are smaller than those obtained by the FHP (NE<sup>m</sup> 2 ), and closer to those obtained in experiments with comparative slaughter. The studies are in an initial phase, and need to be expanded, since they may indicate the change of methodology adopted in the experiments using respirometry. Similar to the NEm, the *k*m by using the "NE<sup>m</sup> 3 " is different from the value obtained by using the "NE<sup>m</sup> 2 ."

there is no improvement in the predictive model with the inclusion of other predictive variables (**Figure 5**). The same occurred with the GE intake (GEI). These data are published [1].

) and dry matter intake (DMI). The points represent the

**Figure 4.** F1 – Holstein × Gyr (left) and Gyr (right) heifers inside the respirometric chamber of the Metabolism and

Several studies have shown that when animal productivity is increased, there is a reduction in the proportion of methane produced per unit of product. According to the United States' Environmental Protection Agency [28], increasing livestock productivity to achieve lower methane emissions per unit of product is the most promising and cost-effective way to reduce emissions. Moderate correlations were obtained (−0.49; *P* = 0.03) in the study by [12], showing that the level of intake relative to maintenance was inversely related to methane production. Increasing the intake by one unit above maintenance resulted in a decrease of 0.73 percentage

units of methane production (%GEI).

Calorimetry Laboratory of the Veterinary School of UFMG.

184 Animal Husbandry and Nutrition

**Figure 5.** Relationship between daily production methane (CH<sup>4</sup>

evaluations considered for the development model (n = 125).

The efficiency of converting DE to ME is influenced by several factors, such as the rate of microbial growth in the rumen, production of methane, relationship between energy and protein in the diet, and efficiency of the use of metabolizable protein, among others. [15] reports that the ME/DE relationship is approximately 0.82. [14, 18] suggest a value between 0.81 and 0.80, respectively; whereas [7] uses values from 0.81 to 0.86. Higher relationships, from 0.89 to 0.92, were found by [30]. An analysis of the relationship between DE intake (DEI)

Energy requirements for maintenance increased during lactation. It was expected since organs and visceral tissues are adapted to metabolize many nutrients during lactation. Dairy Gyr heifer had lower dry matter intake than the Holstein, probably because Gyr gastrointestinal

Respirometry is an excellent technique that allows the evaluation of the same animal many

Animal nutrition knowledge can be improved by using the respirometric technique that is presented as a technology complementary to comparative slaughter, since it allows the deter-

The determination of the nutritional energy requirements for bovines of different genetic groups and under different feeding conditions allows the appropriate adjustment of the for-

The authors would like to acknowledge support provided by the Research Foundation and Support of the State of Minas Gerais (FAPEMIG), National Council for Scientific and Technological Development (CNPq), INCT Animal Science—CNPq, Agricultural Research Company of the State of Minas Gerais (EPAMIG), Veterinary School of Federal University of Minas Gerais (UFMG), Santa Paula Farm—Curvelo (MG), Canoas Farm—Luz (MG), Conesol

\*, Pedro Henrique de Araujo Carvalho<sup>1</sup>

and

,

Respirometry and Ruminant Nutrition http://dx.doi.org/10.5772/intechopen.73009 187

,

, Juliana Sávia da Silva<sup>2</sup>

, Lúcio Carlos Gonçalves<sup>1</sup>

, Warley Efrem Campos2

,

mination of both methane production as well as the efficiencies of energy use.

Agricultural Farm, Campos Altos (MG) and BR-Nova Nutritional Systems.

Parts of this chapter are taken from the authors' former works [31–33].

, Ana Luiza Costa Cruz Borges<sup>1</sup>

, Paolo Antonio Dutra Vivenza2

, Alexandre Lima Ferreira2

, Iran Borges<sup>1</sup>

1 Animal Science Department of Veterinary School of Federal University of Minas Gerais,

2 Veterinary School of Federal University of Minas Gerais, Belo Horizonte, Brazil

\*Address all correspondence to: analuizavetufmg@gmail.com

tract is smaller. In this way, their NEm is smaller too.

mulation of feeds for each animal category.

**Acknowledgements**

**Author details**

Ricardo Reis e Silva1

André Santos Souza<sup>2</sup>

Helena Ferrreira Lage2

Belo Horizonte, Brazil

Eloisa Oliveira Simões Saliba1

Norberto Mario Rodriguez1

times, from birth through life, at different physiological status.

**14. Conclusions**

**Figure 6.** Relationship between digestible energy intake (DEI) and metabolizable energy intake (MEI) expressed as Mcal/ day.

and ME intake (MEI), determined from the metabolism trials in respirometry chambers, was conducted (**Figure 6**).

The data presented show the high dependence of the MEI variable as a function of DEI. It is important to stress that, considering that in all experiments studied, the methane losses were measured in the respirometry chamber and were not estimated, the ME/DE ratio was always greater than 0.82.

## **13. Maintenance and production nutrient requirements**

Many experiments were already carried out at LAMACA. Nutrient requirements data are still scarce, but some observations can be done. When milk production increases, maintenance requirements in relation to total energy requirement decrease. Energy requirements for maintenance in relation to total energy requirement are 50:50, 32:68, 24:76 on 15, 30, and 45 L of milk/day cows, respectively, according to NRC. Zebu cows (like Gyr) and F1 cows have low to medium milk production. Maintenance requirements can mean a good part of total requirements of these cows. Some papers compared animals with different production potential (milk or weight gain) and showed that there is a positive correlation between production ability and maintenance. Dairy Zebu cows' data is still scarce. [13] compared slaughter technique and respirometry in male F1 – Holstein × Gyr on maintenance, intermediate and *ad libitum* energy intake or 1×, 1.5×, or 2× NEm. *Ad libitum* group had higher NEm (+29%). In this group, the heart, liver, kidneys, and gastrointestinal tract weight were 25, 22, 22, 31% bigger, respectively.

Energy requirement of Gyr, F1 – Holstein × Gyr, and Holstein heifers were studied. Gyr had lower maintenance requirement than Holstein, and F1 was intermediate. Gyr heifers were selected for milk production, but maintenance requirement did not increase at the same proportion. It showed us that Zebu cows require less energy for maintenance, so they can be more economic. We also noticed that younger animals have higher maintenance requirements. Energy requirements for maintenance increased during lactation. It was expected since organs and visceral tissues are adapted to metabolize many nutrients during lactation. Dairy Gyr heifer had lower dry matter intake than the Holstein, probably because Gyr gastrointestinal tract is smaller. In this way, their NEm is smaller too.

## **14. Conclusions**

Respirometry is an excellent technique that allows the evaluation of the same animal many times, from birth through life, at different physiological status.

Animal nutrition knowledge can be improved by using the respirometric technique that is presented as a technology complementary to comparative slaughter, since it allows the determination of both methane production as well as the efficiencies of energy use.

The determination of the nutritional energy requirements for bovines of different genetic groups and under different feeding conditions allows the appropriate adjustment of the formulation of feeds for each animal category.

## **Acknowledgements**

and ME intake (MEI), determined from the metabolism trials in respirometry chambers, was

**Figure 6.** Relationship between digestible energy intake (DEI) and metabolizable energy intake (MEI) expressed as Mcal/

The data presented show the high dependence of the MEI variable as a function of DEI. It is important to stress that, considering that in all experiments studied, the methane losses were measured in the respirometry chamber and were not estimated, the ME/DE ratio was always

Many experiments were already carried out at LAMACA. Nutrient requirements data are still scarce, but some observations can be done. When milk production increases, maintenance requirements in relation to total energy requirement decrease. Energy requirements for maintenance in relation to total energy requirement are 50:50, 32:68, 24:76 on 15, 30, and 45 L of milk/day cows, respectively, according to NRC. Zebu cows (like Gyr) and F1 cows have low to medium milk production. Maintenance requirements can mean a good part of total requirements of these cows. Some papers compared animals with different production potential (milk or weight gain) and showed that there is a positive correlation between production ability and maintenance. Dairy Zebu cows' data is still scarce. [13] compared slaughter technique and respirometry in male F1 – Holstein × Gyr on maintenance, intermediate and *ad libitum* energy intake or 1×, 1.5×, or 2× NEm. *Ad libitum* group had higher NEm (+29%). In this group, the heart, liver, kidneys, and gastrointestinal tract weight were 25, 22, 22, 31% bigger,

Energy requirement of Gyr, F1 – Holstein × Gyr, and Holstein heifers were studied. Gyr had lower maintenance requirement than Holstein, and F1 was intermediate. Gyr heifers were selected for milk production, but maintenance requirement did not increase at the same proportion. It showed us that Zebu cows require less energy for maintenance, so they can be more economic. We also noticed that younger animals have higher maintenance requirements.

**13. Maintenance and production nutrient requirements**

conducted (**Figure 6**).

186 Animal Husbandry and Nutrition

day.

greater than 0.82.

respectively.

The authors would like to acknowledge support provided by the Research Foundation and Support of the State of Minas Gerais (FAPEMIG), National Council for Scientific and Technological Development (CNPq), INCT Animal Science—CNPq, Agricultural Research Company of the State of Minas Gerais (EPAMIG), Veterinary School of Federal University of Minas Gerais (UFMG), Santa Paula Farm—Curvelo (MG), Canoas Farm—Luz (MG), Conesol Agricultural Farm, Campos Altos (MG) and BR-Nova Nutritional Systems.

Parts of this chapter are taken from the authors' former works [31–33].

## **Author details**

Ricardo Reis e Silva1 , Ana Luiza Costa Cruz Borges<sup>1</sup> \*, Pedro Henrique de Araujo Carvalho<sup>1</sup> , André Santos Souza<sup>2</sup> , Paolo Antonio Dutra Vivenza2 , Juliana Sávia da Silva<sup>2</sup> , Helena Ferrreira Lage2 , Alexandre Lima Ferreira2 , Lúcio Carlos Gonçalves<sup>1</sup> , Eloisa Oliveira Simões Saliba1 , Iran Borges<sup>1</sup> , Warley Efrem Campos2 and Norberto Mario Rodriguez1

\*Address all correspondence to: analuizavetufmg@gmail.com

1 Animal Science Department of Veterinary School of Federal University of Minas Gerais, Belo Horizonte, Brazil

2 Veterinary School of Federal University of Minas Gerais, Belo Horizonte, Brazil

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## *Edited by Banu Yücel and Turgay Taşkin*

This book focuses on the animal husbandry and nutrition based on significant evaluations by the authors of the chapters. Many chapters contain general overviews on animal husbandry and nutrition from different countries. Also, the sections created shed light on futuristic overlook with improvements for animal husbandry and feeding sector. Details about rearing and feeding different animal races are also covered herein. It is hoped that this book will serve as a source of knowledge and information on animal husbandry and nutrition sector.

Published in London, UK © 2018 IntechOpen © Watcha / iStock

Animal Husbandry and Nutrition

Animal Husbandry

and Nutrition

*Edited by Banu Yücel and Turgay Taşkin*