*2.2.2 Paneth cells*

*Advances in Poultry Nutrition Research*

the nutrient intake as well as compromised output.

**1.2 Factors to be considered for good gut health**

domination of pathogenic bacteria in the gut.

gut development and immune system.

further leads to improvement in production.

absorption.

immunity and production.

**2. Importance of gut health**

The growth and development of poultry industry is crucial in sustaining the supply of safe, nutritious and good quality protein sources to balance the diet composition of humans. Productive performance of poultry had influenced by the host factors like: genetic background (bird species, type of bird, breed and sex), gut development and maturation (immune system, gut morphology and micro biota acquisition) and stress (environmental factors, type/form of feed, poor management, health interventions, litter management, nutrition). Gut health is a major concern and more complex with more than 640 different species of microbiota, over 20 hormones which digest and absorb the majority of the nutrients accounts 20% of energy utilisation [5]. It infers that factors fatal to gut certainly influences

A healthy gastro intestinal tract (GIT) will be able to efficiently carry out activities viz. protection against insults (infectious and non-infectious), transport of ingested feed and digesta through the entire track, digestion, absorption process, hosting microbiota and excretion of undigested feed. Whereas, it may not be possible with a compromised GIT due to various deviations. Factors like nutrients/feed; microbiota and environment/stress will influence the functionality, integrity and health of gut.

1.Environment factors: improper ventilation and temperature causes poor

2.Bio security: poor management and improper bio security leads to the

gut microbes. Mycotoxins in the feed also damage the gut tissues.

4.Challenging situations like vaccination and disease out breaks.

development and functioning of intestinal epithelium both in catabolism and

3.Nutrition: sudden change in feed, feed composition will affect the balance of

5.Early Nutrition/brooding: making the feed available immediately after the hatch fastens the development of gut. Sub optimal management impairs the

their roles, in modulating bird's ability to be resilient towards the infections on

The immune and non-immune cells in the gut interact and help to provide intestinal protection, tolerance and homeostasis. In general, these components work in coordination with each other to maintain homeostasis as well as to prevent diseases, in turn maximise the utilisation of acquisition of dietary nutrients and

Gut health influences nutrient assimilation, intestinal barrier and integrity, immune response and efficiency, inflammatory balance, susceptibility to enteric

Here in this chapter is an insight into the role of gut health and integrity, through

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**2.1 Gut health**

It plays an important immune defence role in the intestine, particularly relating to production of host defence peptides (HDPs), repair of intestinal epithelium especially during damage/inflammation. Paneth cells are majorly located in small intestine crypts. Along with goblets cells, entero ednocrines these will form tight junction. Tight junctions are nothing but multiprotein complexes, form a continuous intercellular barrier between epithelial cells and regular para cellular

**Figure 1.** *Cross section of small intestine.*

permeability. More number of Paneth cells are presents at small intestine crypts i.e. Crypts of Lienerkuhn. These consist of ER, Golgi network and large granules produce HDPs viz. α-defensins/cryptdins, secretory phospholipase A2 and lysozyme.

Antimicrobial peptides or immune modulators released from the Paneth cells protect the host from enteric pathogens. The glycosidase secreted from the paneth cells named Lysozyme, which hydrolyses peptidoglycan and is one of the major components of the bacterial cell wall. Lysozyme also observed in gastric and small intestinal secretions, as well as in the granules of macrophages and neutrophils and the G2-type, which is identified in the small intestine, liver, and kidney [9]. In the gastrointestinal tract, lysozyme C is expressed in the gastric and pyloric glands, duodenal Brunner's glands, and in the Paneth cells.

#### *2.2.3 Enteroendocrine cells*

Even though they are less in number, compared to other intestinal epithelial cell population (about 1%). In response to chemical/mechanical stimuli these cells secretes a variety of hormones viz. GLP-1, GLP-2, PYY, CCK and serotonin. These play a very important role in birds while regulating hormone secretion, gastrointestinal enzymatic activity, and feeding behaviour.

#### *2.2.4 Lamina propria*

Lamina propria is a loose connective tissue. Consist of dendritic cells, macro phages, heterophills, natural killer cells immune cells like T and B cells and intra epithelial lymphocytes.

#### *2.2.5 Microbiota*

Microbiota forms a protective layer by attaching to the epithelial walls of enterocyte and minimise the options for the colonisation of pathogenic bacteria by competitive exclusion. Microbiota plays an important role in production of Short chain fatty acids, organic acids, vitamins (B group and K), bacteriocins (Antimicrobial property), lower triglycerides finally induce non pathogenic responses which give both nutrition and immunity to the bird [10, 11]. Incontrast some of the pathogenic bacteria like Salmonella and camphylobacter which may circulated to humans while consumption may act as a pool for antibiotic resistance and transmission which is having more public health concern [12].

The chicken gut microbiota (**Figure 2**) includes hundreds of bacterial species dominated at the phylum level by Firmicutes (*Lactobacillus, Clostridium, Ruminoccocus, Turicibacter),* Bacteroidetes *(Flavibacterium, Fusobacterium*), Proteobacteria (*Enterobacter*) and Actinobacteria(*Bifidobacterium*). The microbial communities differ throughout the chickens GIT with particular microbial profiles have been detected in crop, gizzard, ileum, cecum and colon of chickens.

Functional output of microbiota includes production of SCFAs [13–15] added metabolic potential and competitive exclusion of pathogens by decreasing the pH. Lactic acid bacteria (LAB) favour renewal and barrier function of the gastrointestinal epithelium by SCFAs production [16].

Fatty acids produced from microbiota plays an important role. Among the SCFAs acetate is produced more followed by propionate and butyrate. Even though less amount of butyric acid is produced it acts as a source of energy for colonic epithelia and helps in maintaining homeostasis at colonocytes and further helps in good morphometry. Functions like enterocyte growth and proliferation, mucin production, intestinal blood flow, intestinal immune response are influenced by the SCFAs.

**101**

initiated [19].

watery gut contents.

*Microbiota in gut of fowl.*

**Figure 2.**

**2.3 Activities in gut**

bial imbalance in the gut of chicken [18].

*Gut Health and Immunity in Improving Poultry Production*

An imbalanced microbes in the gut is termed as Dysbiosis, this imbalance is majorly due to stress, change in nutrition and infections which alters immune system. It causes a sequential reaction in the GIT, including reduced intestinal barrier function (e.g., thinning of intestinal wall) and poor nutrient digestibility, and therefore, increasing the risk of bacterial translocation and inflammatory responses [17]. The severity of dysbiosis varies depending on situation but it is generally characterised by loose and foamy caecal droppings. Post-mortem examination of affected birds reveals thinning of the gut wall along with gassy and

Proper bacterial balance i.e. at least 85% of total bacteria should be good bacteria is vital for the host, and the impact on gut health often comes from micro-

Anti microbial peptides (AMPs) and Ig A are secreted in the gut by the epithelial cells [12]. Mucus layer protects the epithelium and acts as a first line of defence against infection. Small intestine goblet cells in chicks starts functioning in the late embryonic and post hatch period and can be observed by 17th day of incubation. At that time the produced mucin is of acidic in nature. Whereas, until day 7 after post hatch the same goblet cells produce both acidic and neutral mucin. Later age onwards expansion of goblet cell number towards ileal axis get

of that brings about release a low molecular weight peptides [20].

In micobiota phylum Bacteroidetes (i.e., *Bacteroides fragilis*) associated with production of IL-17 producing T cells [19]. Lactobacillus group of commensal bacteria stimulate intestinal immune system and increase the resistance to diseases, as part

*DOI: http://dx.doi.org/10.5772/intechopen.95989*

**Figure 2.** *Microbiota in gut of fowl.*

*Advances in Poultry Nutrition Research*

*2.2.3 Enteroendocrine cells*

*2.2.4 Lamina propria*

epithelial lymphocytes.

having more public health concern [12].

crop, gizzard, ileum, cecum and colon of chickens.

tinal epithelium by SCFAs production [16].

*2.2.5 Microbiota*

duodenal Brunner's glands, and in the Paneth cells.

testinal enzymatic activity, and feeding behaviour.

permeability. More number of Paneth cells are presents at small intestine crypts i.e. Crypts of Lienerkuhn. These consist of ER, Golgi network and large granules produce HDPs viz. α-defensins/cryptdins, secretory phospholipase A2 and lysozyme. Antimicrobial peptides or immune modulators released from the Paneth cells protect the host from enteric pathogens. The glycosidase secreted from the paneth cells named Lysozyme, which hydrolyses peptidoglycan and is one of the major components of the bacterial cell wall. Lysozyme also observed in gastric and small intestinal secretions, as well as in the granules of macrophages and neutrophils and the G2-type, which is identified in the small intestine, liver, and kidney [9]. In the gastrointestinal tract, lysozyme C is expressed in the gastric and pyloric glands,

Even though they are less in number, compared to other intestinal epithelial cell population (about 1%). In response to chemical/mechanical stimuli these cells secretes a variety of hormones viz. GLP-1, GLP-2, PYY, CCK and serotonin. These play a very important role in birds while regulating hormone secretion, gastroin-

Lamina propria is a loose connective tissue. Consist of dendritic cells, macro phages, heterophills, natural killer cells immune cells like T and B cells and intra

Microbiota forms a protective layer by attaching to the epithelial walls of enterocyte and minimise the options for the colonisation of pathogenic bacteria by competitive exclusion. Microbiota plays an important role in production of Short chain fatty acids, organic acids, vitamins (B group and K), bacteriocins (Antimicrobial property), lower triglycerides finally induce non pathogenic responses which give both nutrition and immunity to the bird [10, 11]. Incontrast some of the pathogenic bacteria like Salmonella and camphylobacter which may circulated to humans while consumption may act as a pool for antibiotic resistance and transmission which is

The chicken gut microbiota (**Figure 2**) includes hundreds of bacterial species dominated at the phylum level by Firmicutes (*Lactobacillus, Clostridium, Ruminoccocus,* 

(*Enterobacter*) and Actinobacteria(*Bifidobacterium*). The microbial communities differ throughout the chickens GIT with particular microbial profiles have been detected in

Functional output of microbiota includes production of SCFAs [13–15] added metabolic potential and competitive exclusion of pathogens by decreasing the pH. Lactic acid bacteria (LAB) favour renewal and barrier function of the gastrointes-

Fatty acids produced from microbiota plays an important role. Among the SCFAs

acetate is produced more followed by propionate and butyrate. Even though less amount of butyric acid is produced it acts as a source of energy for colonic epithelia and helps in maintaining homeostasis at colonocytes and further helps in good morphometry. Functions like enterocyte growth and proliferation, mucin production, intestinal blood flow, intestinal immune response are influenced by the SCFAs.

*Turicibacter),* Bacteroidetes *(Flavibacterium, Fusobacterium*), Proteobacteria

**100**

An imbalanced microbes in the gut is termed as Dysbiosis, this imbalance is majorly due to stress, change in nutrition and infections which alters immune system. It causes a sequential reaction in the GIT, including reduced intestinal barrier function (e.g., thinning of intestinal wall) and poor nutrient digestibility, and therefore, increasing the risk of bacterial translocation and inflammatory responses [17]. The severity of dysbiosis varies depending on situation but it is generally characterised by loose and foamy caecal droppings. Post-mortem examination of affected birds reveals thinning of the gut wall along with gassy and watery gut contents.

Proper bacterial balance i.e. at least 85% of total bacteria should be good bacteria is vital for the host, and the impact on gut health often comes from microbial imbalance in the gut of chicken [18].

In micobiota phylum Bacteroidetes (i.e., *Bacteroides fragilis*) associated with production of IL-17 producing T cells [19]. Lactobacillus group of commensal bacteria stimulate intestinal immune system and increase the resistance to diseases, as part of that brings about release a low molecular weight peptides [20].
