Livestock is responsible for most of the GHG emissions in the agricultural sector and accounts for almost 6 percent of all anthropogenic GHG emissions.^[42]

Most of these emissions originate from digestive processes in ruminants and there are limits to what can be done to reduce this source. Therefore, it is likely that the largest abatement gains will have to come from changes in consumer patterns toward less or different meat consumption, as well as avoiding the conversion of natural land into livestock pastures.^[43]

It is likely that the largest abatement gains will have to come from changes in consumer patterns toward less or different meat consumption

Increased focus on recycling of nutrients in all stages of the livestock production process, including reducing food loss and waste, can also make significant contributions.^[44]
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Enteric fermentation

Ruminant livestock, such as cattle, buffalo, goats and sheep, produce large amounts of methane as a by-product of the activity of microbes processing cellulose in their digestive tracts, a process commonly referred to as enteric fermentation. It is estimated that up to 30 percent of all anthropogenic methane emissions originate with ruminants.^[45] Livestock are found in a large variety of agricultural systems, from poor smallholders to large industrial farms, and in all climates. They are often an intrinsic part of cultural, economic and food security aspects of rural livelihoods. Livestock provide not only protein in the form of meat and milk, but also power for traction and transport, manure (for fuel and fertilizer), hides and fibers and a means of accumulating savings, especially for poor households. It is estimated that around 59 percent of the 729 million poor people living in rural and marginal areas are livestock farmers.^[46]

The amount of methane that is released into the atmosphere by ruminants is determined by several factors, including level of intake, type and quality of feed, energy consumed, size and growth rate, production level and ambient temperature.^[47] The way these factors influence the animals varies according to breed, and therefore animal genetics is an additional variable.
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More productive system emit less methane

The factors listed above also indicate that methane emissions vary with the productivity of systems, and high productivity systems have much lower emissions per product produced than less intensive systems, as illustrated in figure 3.3.^[48][49] Therefore, reducing poverty and increasing rural livelihood standards through productivity increases is also likely to have a positive effect on GHG emissions.^[50] In that respect, means for reducing emissions from smallholder livestock may partly overlap with initiatives targeting adaptation, as adaptation is to a large degree about bolstering the resilience and robustness of the most vulnerable through improved livelihood conditions and food security (see also Green Technology Book: Solutions for Climate Change Adaptation).

Figure 2.5 Emissions (in gigatons) caused by material production as a share of global emissions, 1995 versus 2015[136]

Notes: green dots indicate countries. FPCM stands for fat- and protein-corrected milk, which is a standardization measure of milk production; GHG is greenhouse gas. Source: FAO (2019)

Cattle are responsible for around 77 percent of enteric methane emissions, followed by buffalo at 14 percent and small ruminants at 9 percent.^[51] Targeting cattle rearing is therefore a high priority mitigation strategy. With the aim of productivity increases in mind, the three main target areas for bringing down emissions from livestock are feeding, animal health and husbandry, and genetics and breeding.
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Feeds and additives that reduce emissions

Not all feeds result in the same levels of methane emissions from enteric fermentation. Shifting to easily digestible grains and adding nitrates to livestock feed may help reduce methane production and also increase productivity though more efficient digestion.^[52] Feed supplements may also help to reduce emissions. Some additives directly inhibit methane generation while others affect the availability of hydrogen and CO2, resulting in less methane production.^[53] The following section gives a few examples of methane-inhibiting feed additives but this is an innovation-intensive field and hundreds of relevant patents can be found in the WIPO GREEN Database of needs and green technologies.

Furthermore, the protein composition of fodder can be modified to reduce methane emissions. Some of these methane-reducing protein sources include synthetic amino acids, algal, fungal or microbial protein and insects.^[54] Feed is one of the main determinators of animal productivity, and hence the emissions per product produced. Improved feed quality can produce the same amount of animal products with lower methane emissions. Therefore, improved pasture management, forage mix and species, ration balancing and targeted feed preparation and preservation are factors that can be addressed.

Animal health and climate mitigation are complementary

Healthy animals are generally also more productive, so targeting factors that are detrimental to animal health and living conditions will also have a positive effect on methane emissions. This includes issues that influence the reproductive rate and productive lifespan of animals, live-weight, milk yield, fertility, etc.

Selective breeding and conservation of indigenous breeds with specific tolerances can optimize the adaptability of livestock to local conditions, again increasing productivity and thereby reducing methane emissions. Having access to a wide genetic pool through artificial insemination can allow farmers to modify their herds’ ability to thrive in local environments and on locally available feeds, and increase their resilience to climate change.^[55] New breeds developed through genetic modification may have special abilities to optimize digestion of feed resulting in lower emissions, improved resistance to common diseases and stronger resilience to environmental factors such as heat and water stress with associated changes in feed. For more on livestock adaptation options, see the Green Technology Book: Solutions for Climate Change Adaptation.
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Replacement of meat and dietary shifts

Changing consumption patterns for meat and other animal-derived products may well be one of the most important factors for limiting emissions from livestock, simply by having fewer of them. And innovation and technology are providing abundant solutions at a rapid pace. However, meat consumption overall is following a growing trend, although in the short term growth is expected to be modest due to high consumer prices and weak income growth.^[56]

Meat consumption grows with income level

Consumption of meat is correlated with household wealth, meaning that generally, the better off a household is, the more meat it consumes – up to a certain point. Even though poverty and malnutrition are still prevalent in many parts of the world, several very large emerging economies are developing rapidly and raising living standards for substantial parts of their populations. Middle-income countries are therefore the main driver behind increased meat demand. In higher-income countries, disposable income is no longer a main factor determining meat consumption, but people in those countries still consume about seven times more meat than people in low-income countries.^[57] Meat consumption is therefore likely to continue increasing. Add to this global population growth and increased longevity. Currently standing at 8 billion people, the world population is projected to reach 9.7 billion in 2050 with more people added to that total until at least 2100, although with large regional variations and some countries already experiencing shrinking populations.^[58] The population growth factor alone is likely to result in increased meat and dairy product consumption.

From ruminants to alternative proteins

Shifting more meat consumption from ruminants to monogastric species, such as pigs, rabbits, poultry and fish, whose digestive processes produce much less methane, can be one pathway toward reducing the climate change footprint of livestock. However, this approach may be offset by some of these animals being more reliant on grain and pulses as fodder, giving rise to other potential environmental impacts.

Alternative proteins, and in particular cultivated meat, are highly processed and thus may themselves have substantial carbon footprints

In some countries, especially the wealthier ones, there are tendencies for stronger consumer awareness of the environmental and climate change footprint of the meat and dairy industry, of animal welfare and of personal health costs, and many consumer groups are motivated to reduce consumption of such products. In India, for example, religion plays a central role in many people’s preference for a vegetarian diet.^[59] For many, such a change in diet will be achieved by the replacement of meat with other protein sources, especially plant-derived ones. Such a shift in dietary habits will also have environmental benefits as meat is resource inefficient due to the nutrient conversion process that animals represent. The carbon footprint argument is gaining importance in the increasingly competitive market for meat and dairy alternatives,^[60] but as alternative proteins, and in particular cultivated meat, are highly processed and thus may themselves have substantial carbon footprints, it is uncertain how much this trend will contribute to mitigating livestock emissions.

Replacing meat with plant- or fungi-based alternatives and producing meat in ways other than raising and killing animals, has gained considerable media attention and capital investments in recent years (figure 3.4).^[61]The Protein Directory, a web-based database of alternative protein companies, contains more than 1,800 listings and is growing fast, although not all companies directly target replacing meat and animal protein.^[62] Replacing live animal-based protein can be achieved in several ways. Cutting-edge technologies include cellular agriculture (or cultivated meat) where meat cells are produced in bioreactors or by in vitro cultivation based on original live animal cells, processing of plant-derived proteins into milk- and meat-like products, precision fermentation, 3D printing, fungi fermentation and microbe cultivation.

It is also possible to genetically modify plants and microflora (yeast) to produce animal proteins which can improve the texture, taste and nutritional value of meat alternatives. The alternative protein technologies experiencing the fastest growth and those companies that have received the greatest amount of investment are the plant-based processes, probably because these are relatively well tested and can enter the market more quickly.^[63] Selling cultivated meat is, to date (mid-2023), only permitted in Singapore and the United States. Nevertheless, there are already more than 150 companies working on developing and scaling up this technology.^[64] Insect-based meat alternatives offer another line of development, which has the advantage of ease of farming and a wide variety of feeding options. Still in development, this option has so far mainly targeted the animal feed and pet food sectors.^[65]

 
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Range management and avoided land use change

Most livestock are reared in mixed crop–livestock systems, often including trees and occupying vast swathes of land area. Livestock is the largest driver of deforestation globally, not least in Latin America where it is dominant.^[66] This process of converting forest and other land cover types into rangelands and mixed forestry and grazing (silvo-pastoral) systems leads to the release of carbon from burning trees and undergrowth that are not being replaced (replanted). Reducing livestock-related deforestation is one of the largest potential mitigation measures to combat livestock GHG emissions. However, grazing areas and rangelands also contain large amounts of sequestered carbon and maintaining healthy and well-managed grazing lands can increase the soil carbon content still further.

Range management in non-equilibrium

In regions of high rainfall variability, such as the arid to semi-arid Sudanian and Sahelian climate zones where livestock grazing is typically based on commons management, the interplay of grazing pressure, rainfall and land degradation has been debated for decades.^[67] The discussion has been fueled not least by ideas inspired by political ideology such as the tragedy of the commons, first published in 1968,^[68][69] and land tenure in general. The basic notion of non-equilibrium rangeland theory is that high rainfall variability is a more important factor for determining soil and vegetation health than livestock grazing pressure. Rangelands have been found to be able to regenerate quickly when abundant rain arrives.^[70] This view opposed often popularized images of advancing deserts and sand dunes and permanent conversion of a given number of hectares annually into irreversibly degraded land.^[71][72] Actually, land cover types such as forests in more stable rainfall regimes can to some degree also be characterized as not being in an equilibrium or climax vegetation state as they are often made up of a patchwork of areas in various stages of regeneration from some kind of disturbance.

The non-equilibrium ideas are important for a clear understanding of range management. For example, a term such as carrying capacity (a non-static measure of the population size that can be sustained in a given land area) becomes much less useful in areas of high rainfall variability as it is based on more stable and predictable environments. This again has implications for rangeland management, as grazing patterns are required that provide more flexibility than can be achieved by rotation between fixed and fenced pastures. This favors traditional seasonal and opportunistic systems of cattle migrations, transhumance, etc.^[73][74]

Regenerating the rangelands

Regenerative grazing is a term that covers various initiatives aiming to maintain productive grazing lands without the use of artificial fertilizers and preserve or increase their soil carbon content.^[75] The practice The system can include improved grazing management such as grazing rotation to ensure optimal regrowth (for example, through sensor and information technology (IT)-based range management tools and solar-powered electric fences), using specific plant species, providing protection against soil erosion and integrating trees into rangelands.^[76] Restoring degraded rangelands through regenerative grazing promotes soil carbon accumulation and can even qualify for carbon credits, thus adding a further economic incentive. However, regenerating degraded rangelands takes time and the permanence of the measures must be continuously verified. Considering the vast areas of land involved, the potential is large.

Restoring degraded rangelands through regenerative grazing promotes soil carbon accumulation and can even qualify for carbon credits

Land used for cultivating livestock fodder can also sequester carbon if managed well. This means that technologies for optimizing grazing and rangeland management can not only reduce loss of soil carbon on degraded lands but can also allow those lands to act as carbon sinks by increasing soil carbon sequestration.

With increased access to satellite-based internet coverage at close to normal consumer prices, the possibility of connecting various sensors becomes more relevant, providing farmers with real-time data on temperature in sheds, herd movements, water quality, feed silo status, etc. Radio frequency identification (RFID) tags have been in widespread use for years and allow for closer monitoring of the health and condition of individual animals.

As discussed above, general livestock productivity improvements are likely to also reduce GHG emissions per product produced, and all technologies that contribute to productivity increases would therefore be relevant. The focus in this chapter is on technologies that are capable of targeting GHG emissions reduction more or less directly, but it should be kept in mind that the field of productivity-improving solutions is much larger and broader than can be covered here. Another technological field is the capture of methane gas from manure. This can range from simple farm-level installations, basically consisting of large rubber bags or coatings, to industrial-scale bioreactors possibly including equipment for gas purification and compression. Collection of manure from individual farms (for example in scaled-up installations) has turned out to be a challenge in certain settings.

It should also be noted that many solutions address both adaptation and mitigation simultaneously. The Green Technology Book collection in the WIPO GREEN Database of needs and technologies contains many more examples of technologies that are relevant for both adaptation and mitigation.
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