**5. Conventional and nonconventional forage sources**

As expressed before in this chapter, the increasing global population demands for a higher feed production, converting animal feeding production into a natural competitor for human feeding production in the search for arable lands. Consequently, diverse researches have focused into trying different forage sources which were not conventional as animal feeding before but now could be considered as alternative forage sources [38, 39]. Nonconventional forages include a wide variety of perennial plants and agriculture and commercial by-products

*Livestock Health and Farming*

**3.2 Fibrous carbohydrates**

**3.3 Bypass protein**

**4. Feed additives**

decreases microbial protein synthesis through reductions in the abundance of ammonia-utilizing cellulolytic bacteria [14]. Moreover, high NFC concentrations

It has been demonstrated that increases in dry matter intake reduce methane production [15]. Moreover, increases in digestibility is expected in fibrous material whether it is fine ground, as well as augmentations in the passage rate through increases in the turnover rate. Therefore, if turnover rate is increased, the passage rate would also increase. Hence, through augmentations in the passage rate, microorganisms that possess a lower growth rate, such as protozoa and archaea, will defaunate, thus decreasing methane production [16]. Otherwise, digestibility and methane production could be increased by increasing the retention time [17]. Additionally, by increasing the intake above the minimum for maintenance, the animal methane production will arise proportionally. This phenomenon will provoke a reduction in methane production per production unity [18]. Therefore, an animal fed under a pasture basis will produce less methane as part of the GHG produced compared to an animal fed with a high-concentrate or high-fiber proportion diet.

The protein contained in ruminants' feedstuffs could be divided into two groups: degradable rumen protein (DRP) and undegradable rumen protein (URP). The first is degraded in rumen, and it is used as a nitrogen source in the microbial protein synthesis; the second escapes from ruminal degradation and is transported to the lower tract where it is susceptible of being absorbed by the animal in the form of amino acids [19]. In spite of several reasons to name it bypass protein, one of the main characteristics is its low retention time in rumen or, the inverse action, the high passage rate. In the case of high passage rates, microorganisms which possess a low growth rate will tend to defaunate; this is the case of the methanogens. Thus, methanogenesis will be affected and methane production will be reduced. Nowadays, some secondary metabolites are identified as protein protectors, by forming complexes with proteins and avoiding their degradation in rumen. The latter allows proteins to go through the low tract and to be absorbed after liberating

Some strategies are focused on providing feed additives to modify the presence or absence of methanogens, protozoa, or the direct or indirect inhibition of ruminal methanogenesis [21]. By supplementing feed additives, good results are observed in methane production and productive performance. These strategies imply the use of high nutritive quality forages, organic acids, ionophores, probiotics, vegetable extractives, and secondary metabolites from different plants [22]. However, the

• *Ionophores*: Ionophores are additives which possess a proved antimicrobial effect on some ruminal and cultivable strains, especially gram-positive bacteria [23]. Ionophore compounds like monensin and lasalocid have demonstrated to modify rumen fermentation and decrease methane emissions. The latter can be elucidated due to the fact that ionophores, as mentioned earlier, present

complexes due to the acidic pH in the intestine [20].

most used are presented and briefly discussed:

tend to increase VFA production which could cause ruminal acidosis.

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which do not compete with human feeding. Therefore, diverse advantages can be observed when utilizing alternative forages such as (a) a considerable reduction in the feeding source costs; (b) exploitation of nutrients contained in agriculture by-products which otherwise would not be used (these by-products could be high in rapidly digestible carbohydrates or in fiber, both suitable for ruminants); and (c) an increase in the by-product cost which eventually will create economic benefits for producers and the productivity chain supply. Moreover, some agricultural by-products do not need any processing to be offered as animal feeding, hence the desirability of these by-products. Some of the ruminants feeding produced under this basis are:


Some farmers are still not aware of the nutritional value contained in byproducts or in the form to be included into the productivity chain of animal feeding in an efficient way. In this regard, Asia and Africa are heavily focused on attempting to reach this goal. Due to the nature of some agricultural by-products, these tend to decompose in a short time. Hence, some techniques should be used to preserve and increase their shelf life. Therefore, some of the preservation techniques commonly used are listed as follows:


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*Climate Change Mitigation in Livestock Production: Nonconventional Feedstuffs and Alternative…*

their nutritional value and turn this into a more versatile practice.

elaborated to supplement vitamins and minerals, such as zinc and copper [49]. However, recent investigations are using more ingredients to improve

IV. *Supplementation*: Supplementation is extensively used, especially if there is a deficient feed due to poor nutritional quality of some ingredients. By using this technique, some essential nutrients will be delivered to the livestock which otherwise could not be obtained by the animal itself. Nevertheless, the acquisition of ingredients for supplementation is unaffordable for some small producers. On the other hand, there are certain agricultural by-products which could be offered to the livestock and contain certain important nutrients at very low or even null cost. In this way, shrub and tree seeds could be a very good option. *Leucaena*, guamuchil, and ebony seeds are rich in protein and unsaturated lipids; these are being used without any affections in productive performance in small ruminants at very low cost. In this way, shrubs and trees seeds could be a very good option. Leucaena, *Vicia faba*, ebony and other seeds are rich in protein and unsaturated lipids; these are being used without any affections in productive performance in

In the last years, ruminants have been target of several feeding strategies aiming to reduce ruminal methane production and emissions; most of them have been stated earlier in this chapter. However, the use of secondary metabolites arises as a viable and newer alternative in this concern. There is evidence which proves certain secondary metabolites, such as condensed tannins, saponins, and alkaloids, reduce methane production in in vivo and in vitro assays [54]. Generally, the mechanisms

I.**Tannins**: Tannins are water-soluble polyphenol polymers with a high and diverse molecular weight. They can form complexes with proteins, mainly, and metal ions, amino acids, and polysaccharides in a lesser extent. These metabolites are normally synthetized in shrubs, trees, legumes, fruits, cereals, and grains [55]. Tannins are divided into two groups: condensed tannins

*Hydrolysable tannins*: These are complex molecules attached to a polyol group as a central core which are partially or fully esterified with a phenolic group (e.g., gallic acid). The remaining phenolic groups could be later esterified or oxidized to

*Condensed tannins*: These compounds are also known as proanthocyanidins and

II. **Saponins**. According to their chemical structure, they are divided into two groups: steroids and triterpenoids. Steroids are predominantly in

are mainly polymers of the flavan-3-ol units which are bind by interflavonoids C3-C8 and C4-C6 linkages, such as catechin and epicatechin. The methanogenic activity conferred to tannins is mostly due to the condensed tannins; CTs attach to proteins and avoid their degradation in rumen. Additionally, CT decrease methanogenesis through a reduction in fiber digestion [56]. Some studies affirm that CT enhances acetate formation via acetogenesis; this metabolic pathway uses hydrogen

of action of these compounds point out to certain metabolic pathways:

(CTs) and hydrolysable tannins (HTs).

for acetate synthesis and reduces methanogenesis [57].

produce more complexes with HTs [55].

*DOI: http://dx.doi.org/10.5772/intechopen.89433*

small ruminants at a very low cost [50–53].

**6. Plant metabolites**

*Climate Change Mitigation in Livestock Production: Nonconventional Feedstuffs and Alternative… DOI: http://dx.doi.org/10.5772/intechopen.89433*

elaborated to supplement vitamins and minerals, such as zinc and copper [49]. However, recent investigations are using more ingredients to improve their nutritional value and turn this into a more versatile practice.

IV. *Supplementation*: Supplementation is extensively used, especially if there is a deficient feed due to poor nutritional quality of some ingredients. By using this technique, some essential nutrients will be delivered to the livestock which otherwise could not be obtained by the animal itself. Nevertheless, the acquisition of ingredients for supplementation is unaffordable for some small producers. On the other hand, there are certain agricultural by-products which could be offered to the livestock and contain certain important nutrients at very low or even null cost. In this way, shrub and tree seeds could be a very good option. *Leucaena*, guamuchil, and ebony seeds are rich in protein and unsaturated lipids; these are being used without any affections in productive performance in small ruminants at very low cost. In this way, shrubs and trees seeds could be a very good option. Leucaena, *Vicia faba*, ebony and other seeds are rich in protein and unsaturated lipids; these are being used without any affections in productive performance in small ruminants at a very low cost [50–53].
