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June 8th Reviewed: December 8th Published: This chapter outlines the role of livestock in the production of greenhouse gases GHGs that contributes to climate change. As animal production systems are vulnerable to climate change and are large contributors to potential global warming, it is vital to understand in detail enteric CH4 emission and manure management in different livestock species. Methane emissions from livestock are estimated to be approximately 2.
Other sources of GHG emission from livestock and related activities are fossil fuels used for associated farm activities, N2O emissions from fertilizer use, CH4 release from the ar4_sur_spm of fertilizers and from animal manure, and land-use changes for feed production.
There are several techniques available to quantify CH4 emission, and simulation models offer a scope to predict accurately the GHG emission from a livestock enterprise as a whole. Quantifying GHG emission from livestock may pave the way for understanding the role of livestock to climate change and this will help in designing appropriate mitigation strategies to reduce livestock-related GHGs. Indeed, average global temperatures have risen considerably, and the IPCC [ 1 ] predicts increases of 1.
As animal production systems are vulnerable to climate change and are large contributors to potential global warming through methane CH 4 and nitrous oxide N 2 O production, it is vital to understand in detail enteric CH 4 emission and manure management in different livestock species [ 4 ].
Before targeting GHG reduction strategies from enteric fermentation and manure management, it is important to understand the mechanisms of enteric CH 4 emission in livestock, the factors influencing such emission.
In addition, an understanding of the available prediction models and estimation methodology for quantification of GHGs is aesessment. A thorough understanding of these will in turn pave way for formulation of effective mitigation strategies for minimizing enteric CH 4 emission in livestock [ 5 ]. This chapter will focus on four main areas: FAO estimated that million cattle and buffaloes and million small ruminants are being maintained globally. The population of cattle and buffaloes and small ruminants is expected to be 2.
Furthermore, livestock are an integral element of agriculture that supports asssessment livelihood of more than qr4 billion people across the globe. This increased requirement will be fulfilled either by increasing the livestock numbers or through intensifying the productivity of existing stock. Climate change is seen as a major threat to the survival of many species, ecosystems, and the sustainability of livestock production systems in many parts of the world [ 6 ]. The growing human population will almost doubled the global requirement for livestock products by It is during the same period adverse changes in the climate are also expected.
Recent industrial developments have curtailed the land used for agricultural activities, considerably threatening food security in both developed and developing countries. Hence, livestock production has a key role to play in bringing food security to these countries. We assessmment high-quality research in animal science to meet the increasing demand for livestock products in the changing climate scenario [ 7 ].
There are two sources of GHG emissions from livestock: Methane production appears to be a major issue and largely arises from natural anaerobic ecosystems, and fermentative digestion in ruminant animal [ 10 ].
IPCC Fourth Assessment Report on Global Climate Change – Summary | Sustainable Furnishings Council
Much of the global GHG emissions currently arise from enteric fermentation and manure from grazing animals. The development of management strategies to mitigate CH 4 emissions from ruminant livestock is possible and desirable. Carbon dioxide CO assewsment are also produced in livestock sr4 and are primarily associated with fossil fuel burning during operation of farm machineries in the process of fertilizer production, processing and transportation of refrigerated products, deforestation, desertification, and release of carbon from cultivated soils.
Ruminant animals, such as cattle, sheep, buffaloes, and goats, are unique due to their special digestive systems, which can convert plant materials that are indigestible by humans into nutritious food. In addition to food, these animals also produce hides and fibers that are utilized by humans. This same helpful digestive system, however, produces CH 4a potent GHG that can contribute to global climate change. According to Sejian et al. The principal sources of N 2 O are manure and fertilizers used in the production of feed.
The biggest source of CH 4 is from assess,ent fermentation. The rising demand for livestock products therefore translates into rising emissions of CH 4 and N 2 O. A4 to one study, if current dietary trends increasing global consumption of animal products were to continue, emissions of CH 4 and N 2 O would more than double by from levels [ 14 ]. Worldwide livestock emits around 7. Methane emissions from livestock have two sources, one from enteric fermentation and another from excrement. Reducing the loss of energy in the form of enteric CH 4 is crucial, especially in developing countries like India where feed and fodder availability is already in short supply.
India has approximately million livestock 19th Livestock census, Government of India. Emissions of enteric CH 4 can be elevated when these species are fed fibrous feeds. Estimations of enteric CH 4 emissions from Indian livestock have been calculated using different approaches Table 1.
There is a lack ar4_syr_wpm consistency in the published data; some have reported very high emissions from Indian livestock while others have reported much lower emissions [ 15 ].
This large variation in predicted enteric CH 4 emission from Indian livestock is attributed to the different approaches used for the calculation of emissions. The average of the published data is in the range of 9—10 Tg per year, which appears to be a realistic value. Methane emissions from excrement in India are sr4 because the disposal system generally stored as heap in the open environment does not support the favorable anaerobic conditions required by methanogens.
However, in the developed world where excrement is mainly stored in lagoons, manure is a major source of CH 4 emissions. Pig production is the next major emitter contributing 0. The contribution from other livestock species is negligible. The rumen is the harbor for diverse anaerobic microbe populations that accomplish different functions from degradation of complex carbohydrates to the removal of fermentation metabolites in a syntrophic way [ 26 ].
H 2which is produced in large volumes during enteric fermentation, needs to be removed from the anaerobic vat in order to maintain favorable rumen conditions for both the rumen microbes and host animal. Under normal rumen functioning, metabolic H 2 is used for the reduction of CO 2 to CH 4which in turn is eructated into the atmosphere via the mouth and nostrils.
The microbes of the so-called archaea repot methanogens are the CH 4 producing machinery inside the rumen.
ORCA Database – Institute for Tribal Environmental Professionals
The majority of the rumen methanogens are hydrogenotrophic, which utilize H 2 as a substrate for methanogenesis. Among the various end products of rumen fermentation, H 2 is a central metabolite where its partial pressure in the rumen determines the extent of methanogenesis and the possible extent of oxidation of feedstuffs [ 27 ].
H 2 in the rumen is generally referred as currency of fermentation [ 27 ]. The removal of H 2 from the rumen is a prerequisite for the continuation of rumen fermentation. However, the methanogens constitute only a small fraction of the rumen microbial community, but they are very crucial in H 2 utilization [ 28 ].
Apart from the methanogenesis, other hydrogenotrophic pathways reductive acetogenesis, sulfate and nitrate reduction are also present in the rumen, but the extent of H 2 utilization through these pathways is not clear.
In order to keep the rumen functional and the animal alive, rumen methanogenesis is the primary and thermodynamically efficient way ar4_sy_rspm metabolic H 2 disposal from the rumen, and that is why it is generally regarded as a necessary but wasteful process. Several methods are available for measuring enteric CH 4 production, and the selection of the most appropriate method assessmwnt based on adsessment factors such as cost, level of accuracy, and experimental design [ 2930 ].
By far, the most suitable method to quantify individual ruminant animal CH 4 measurement is by using respiration chamber, or calorimetry. Str respiration chamber models include whole animal chambers, head boxes, or ventilated hoods and face masks. These methods have been effectively used to collect information pertaining to CH 4 emissions in livestock. The predominant use of calorimeters has been in energy balance experiments where CH 4 has been estimated as a part of the procedures followed.
Although syyr are various designs available, open-circuit calorimeter has been the one widely used. The tracer can either be isotopic or nonisotopic. Isotopic tracer techniques generally require simple experimental designs and relatively straightforward calculations [ 31 ].
Livestock as Sources of Greenhouse Gases and Its Significance to Climate Change
Various aspects of in vitro gas production test have been reviewed by Getachew et al. Another in vitro automated pressure transducer method for gas production measurement was developed by Wilkins [ 34 ], and the method was validated by Blummel and Orskov [ 35 ] and Makkar et al. Manure from livestock includes both dung and urine. Manure management plays a key role in amount of CH 4 and N 2 O produced and liberated into the environment. The amount of CH 4 produced in solid-state manure management contribute less when compared to liquid state.
However, dry anaerobic management system provides suitable environment for N 2 O production. Various factors that affect CH 4 and N 2 O production include the amount of manure, the VFA present, the type of feed, the management systems, and the ambient temperature.
In addition, the duration of the storage of waste also influences N 2 O production. Anaerobic digestion processes occur in manure with the help of microbial consortia to produce CH 4 and CO 2 and consists of four phases: The aforementioned four phases are done by four different groups of bacterial consortia, namely, hydrolytic bacteria, acidogenic bacteria, acetogenic bacteria, and methanogenic bacteria, respectively [ 43 ].
CH 4 is also emitted from the collection yard, but it is a minor source. The greatest amount of CH 4 is emitted during storage especially in slurry, the reason being the prevalence of complete anaerobic environment. Solid manure also acts as a source of CH 4 emission. CH 4 is emitted immediately after manure application to the field; however, once the O 2 diffuses into manure, it inhibits CH 4 production [ 44 ].
There are several factors that affect the CH 4 production from manure, which includes temperature, organic matter present, microbe load, pH, moisture, and type of feed.
However, CH 4 emitted from manure depends primarily on i the management system such as solid disposal system, liquid disposal systems, e. The higher the temperature and moisture, the more CH 4 produced. Manure handled in liquid form tends to release more amount of CH 4 when compared to solid or manures thrown into the pasture, which do not decompose anaerobically.
High temperatures with neutral pH and high moisture content enhance CH 4 production [ 45 ]. Nitrous oxide is produced from manure by nitrification, denitrification, leaching, volatilization, and runoff.
Nitrification and denitrification are direct emissions. N 2 O is 16 times more potent than CH 4 and times more potent than CO 2 over a year period [ 46 ]. The emission of N 2 O from manure occurs directly by both nitrification and denitrification of nitrogen contained in the manure. This emission mainly depends on the N and C content of the manure during various types storage and treatment.
The nitrification process strictly needs oxygen, while subsequent denitrification is an anaerobic process. Manure from livestock mixes with the soil or in the tank, lagoons, etc. In this step, the organic N becomes available for plants and microorganisms. Studies show that N 2 O was emitted from animal houses at the rate of 4—5 mg N m -2 d -1with straw as bedding material, whereas when no bedding material was used, little or no N 2 O was emitted from slurry-based cattle or pig building as complete anaerobic condition would have maintained [ 52 ].
Deep litter system with fattening pigs showed much higher emission compared to slurry based pig houses, while mechanical mixing still further increased N 2 O emission [ 53 ]. Covering heaped manure shows reduction in NH 3 emissions but has no effect on N 2 O emission, while other studies showed that both were reduced.