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Grazing can be optimized by finding the right balance among the different users of the land and adapting grazing practices accordingly. Optimal grazing leads to improved grassland^x productivity and delivers adaptation and mitigation benefits. However, the net influence of optimal grazing is variable and highly dependent on baseline grazing practices, plant species, soils and climatic conditions (Smith et al., 2008).

One of the main strategies for increasing the efficiency of grazing management is through rotational grazing^xi, in which the frequency and timing of grazing is adjusted to match the livestock’s needs with the availability of pasture resources. Through targeted temporal grazing exclusions, rotational grazing allows for the maintenance of forages at a relatively earlier growth stage. This enhances the quality and digestibility of the forage, improves the productivity of the system and reduces methane emissions per unit of live weight gain (Eagle et al., 2012). Rotational grazing is more suited to manage pasture systems, where the investment costs for fencing and watering points, additional labour and management that is more intensive are more likely to be recouped.

In colder climates, where animals are housed during cold periods, there are also opportunities for controlling the timing of grazing to avoid grassland degradation and adapt the grazing to the timing of vegetation growth to optimize the intake. For example, early grazing of summer pastures is a major cause of grassland degradation in Northern China (see Case study B2.1 on range management for mitigation and adaptation). Delaying grazing until the grass sprouts have reached a more advanced stage of maturity is an important sustainable grazing practice.

Furthermore, increasing livestock mobility, a traditional strategy of nomadic and transhumant herders in many parts of Africa for matching animal production needs with changing rangeland resources, can significantly enhance the resilience of these livestock systems to climate change (drought in particular). Land tenure reforms to deal with the encroachment of cultivated lands and other land uses that impede livestock mobility will be needed (Morton, 2007).

The most clear-cut mitigation benefits perhaps arise from soil carbon sequestration that results when grazing pressure is reduced as a means of stopping land degradation or rehabilitating degraded lands (Conant and Paustian, 2002). In these cases, enteric emission intensities can also be lowered, because with less grazing pressure animals have a wider choice of forage, and tend to select more nutritious forage, which is associated with more rapid rates of live weight gain (Rolfe, 2010). By restoring degraded grassland, these measures can also enhance soil health and water retention, which increases the resilience of the grazing system to climate variability. However, if grazing pressure is reduced by simply reducing the number of animals, then total output (e.g. milk, meat) per hectare may be lower, except in areas where baseline stocking rates are excessively high (Rolfe, 2010).

Pasture^xii management measures involve the sowing of improved varieties of pasture, typically replacing native grasses with higher yielding and more digestible forages, including perennial fodders, pastures and legumes (Bentley et al., 2008). For example, in tropical grazing systems of Latin America, substantial improvements in soil carbon storage and farm productivity, as well as reductions in enteric emission intensities, are possible by replacing natural cerrado vegetation with deep-rooted pasture species, such as Brachiaria (Thornton and Herrero, 2010). However, there are far fewer opportunities for sowing improved pastures in arid and semi-arid grazing systems.

The intensification of pasture production though fertilization, cutting regimes and irrigation practices may also enhance productivity, soil organic carbon, pasture quality and animal performance (e.g. milk or meat yield). These approaches however, may not always reduce greenhouse gas emissions. Improving pasture quality through nitrogen fertilization may involve trade-offs between lower methane emissions and higher nitrous oxide emissions (Bannink et al., 2010). In addition, after accounting for energy-related emissions and nitrous oxide emissions associated with irrigation, the net greenhouse gas emissions of this practice may be negative on grazing lands (Eagle et al., 2012). Grass quality can also be improved by chemical treatments (e.g. the use of ammonia) and/or mechanical actions (e.g. chopping, grinding, and ensiling). Both synergies and trade-offs can exist between pasture management and biodiversity conservation. Biodiversity conservation can be a constraint to pasture intensification, as fertilization, sowing, irrigation and high stocking rates usually lead to grasslands that have fewer plant species and provide less resources (food, habitat) for animals, and are consequently less rich in biodiversity (Vickery et al., 2001; Kleijn et al., 2009). At the same time, grassland abandonment is also a threat to biodiversity. The highest diversity of wild species is often found in pastures with intermediate levels of management intensity (FAO, 2016a). Certain grassland management practices, such as adjusting the timing and intensity of grazing, setting up buffers to protect wild habitats, introducing supplementary feeding or nutrient management can provide multiple co-benefits for carbon sequestration, land restoration and biodiversity conservation (FAO, 2016b). The role of biodiversity conservation for sustainable agricultural intensification and climate change adaptation is addressed in module B8. 

With increasing variability in climatic conditions (e.g. increasing incidents of drought), there may be an increase in the frequency of periods where forage availability falls short of animal demands. In these situations, supplemental feeding can be an important adaptation strategy.

As discussed in Chapter B8-3 on animal genetic resources, breeding more productive animals is a strategy to enhance productivity and thereby lower methane emission intensities. Research has started on the mitigation benefits of using residual feed intake as a selection tool for low methane-emitting animals, but findings have been inconclusive (Waghorn and Hegarty, 2011).

Crossbreeding programmes can deliver simultaneous adaptation, food security and mitigation benefits. For example, composite cattle breeds developed in recent decades in tropical grasslands of northern Australia have demonstrated greater heat tolerance and disease resistance, and better fitness and reproductive traits compared with pure shorthorn breeds that had previously dominated these harsh regions (Bentley et al., 2008). In general, crossbreeding^xiii  strategies that make use of locally adapted breeds, which are not only tolerant to heat and poor nutrition, but also to parasites and diseases (Hoffmann, 2008), may become more common with climate change.

Adaptation to climate change can also be fostered by switching livestock species. For example, the Samburu of northern Kenya, a traditionally cattle-keeping people, adopted camels as part of their livelihood strategy. This switch allowed them to overcome a decline in their cattle economy, which, from 1960 onwards, had been affected by drought, cattle raiding and animal disease (Sperling, 1987). 

As with all livestock production systems, there are a number of animal and herd management options for land-based systems that can enhance animal productivity, improve feed conversion efficiency and thereby reduce enteric emission intensities. Improving animal husbandry through activities that ensure proper nutrition and appropriate feeding and reproductive strategies, regularly maintaining animal health and using antibiotics responsibly can improve reproduction rates, reduce mortality and lower the slaughter age. All of these measures will increase the amount of output produced for a given level of emissions. The impacts of these measures on adaptation are likely to be neutral.

In addition to enhanced animal health management to maintain and improve animal performance, as discussed in Chapter B2-2.1, the management of disease risks may also become increasingly important because there may be an increase in the emergence of gastro-intestinal parasites due to climate change (Wall and Morgan, 2009). Breeding more disease resilient animals is one approach to addressing this issue.

Most methane emissions from manure derive from swine and beef cattle feedlots and dairy cattle, where production is carried out on a large scale and manure is stored under anaerobic conditions. Greenhouse gas mitigation options include the capture of methane by using biogas collectors to cover manure storage facilities. The captured methane can be flared or used as a source of energy for electric generators, heating or lighting. An example of energy generated in this way to offset carbon dioxide emissions from burning fossil fuels is presented in Box B2.5. The climate change adaptation and mitigation benefits of production systems that integrate food and energy production are considered in module B5, while the management of energy in the context of climate-smart agriculture is addressed in module B9.

Anaerobic digestion technology harnesses microorganisms to degrade organic materials, including manure, in containers where oxygen is absent to produce methane that can be used for heating, cooking or energy production. This technology has been shown to be highly profitable in warm climates (Gerber et al., 2008). Recent developments in energy policy have also enhanced its economic profitability in countries such as Denmark and Germany (AEBIOM, 2009). Manure application practices can also reduce nitrous oxide emissions. Improved livestock diets, as well as feed additives, can substantially reduce methane emissions from enteric fermentation and manure storage (FAO, 2006). Energy-saving practices have also been demonstrated to be effective in reducing the dependence of intensive systems on fossil fuels.

Carbon dioxide emissions associated with feed production, especially soybean, are significant (FAO, 2006). Improved feed conversion ratios have already greatly reduced the amount of feed required per unit of animal product. However, there is significant variation between production units and countries. 

Further progress is expected to be made in this area through improvements in feed management and livestock breeding. Reducing the amount of feed required per unit of output (e.g. beef, milk) has the potential to both reduce greenhouse gas emissions and increase farm profits. Feed efficiency can be increased by developing breeds that grow faster, are more hardy, gain weight more quickly, or produce more milk. Feed efficiency can also be increased by improving herd health through better veterinary services, preventive health programmes and improved water quality.

Shifting to feed resources with a low-carbon footprint is another way to reduce emissions, especially for geographically concentrated pig and poultry production systems. Examples of low-emission feeds include feed crops that have been produced through conservation agriculture or that have been grown in areas that have not been recently extended into forested land or natural pastures. Crop by-products and co-products from the agrifood industry are also examples of low-emission feeds.

Landless systems generally rely on greater amounts of fossil fuel energy than integrated crop-livestock  and grazing systems  (FAO, 2009; Gerber et al., 2011). Energy is used at different stages, such as for advanced cooling technologies (e.g. sprays or fans that cool the animals), water use, and production of a range of feedstuffs. To a large extent, this protects the high-output animals used in landless systems against the direct effects of high temperatures. In these situations, the main question is economic: is the cost of adapting the production environment, including ongoing higher expenditures on inputs, is more or less than the cost of not adapting or changing the animal genetic resources by potentially switching to less productive breeds? Small-scale producers who have adopted high-output breeds but struggle to obtain the capital to purchase the inputs needed to prevent the animals from becoming overheated may find that their problems are exacerbated by climate change. Improving energy use efficiency, i.e. amount of energy used per unit of product, is an effective way to reduce production costs and lower emissions. 

Dairy farms are seen as having great potential for energy use efficiency gains. Energy is used for the milking process, cooling and storing milk, heating water, lighting and ventilation. Cooling milk generally accounts for most of the electrical energy consumption on a dairy farm in developed countries. Cows are milked at temperatures around 35 to 37.5 degrees Celsius. To maintain high milk quality, which includes keeping bacteria counts low, the raw milk temperature needs to be lowered quickly to 3 to 4 degrees Celsius. Refrigeration systems are usually energy-intensive. Heat exchangers cooled by well water, variable-speed drives on the milk pump, refrigeration heat recovery units and scroll compressors are all energy conservation technologies that can reduce the energy consumed in the cooling system. These technologies can reduce greenhouse gas emissions, especially in countries where the energy sector is emission intensive. See Case study B2.4.