Editing IPCC:AR6/SRCCL/Chapter-5 (section)

==== 5.5.1.2 Greenhouse gas mitigation in livestock systems ====

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The technical options for mitigating GHG emissions in the livestock sector have been the subject of recent reviews (Mottet et al. 2017b <sup>[[#fn:r811|811]]</sup> ; Hristov et al. 2013a,b; Smithers 2015 <sup>[[#fn:r812|812]]</sup> ; Herrero et al. 2016a <sup>[[#fn:r813|813]]</sup> ; Rivera-Ferre et al. 2016b <sup>[[#fn:r814|814]]</sup> ) (Figure 5.11). They can be classified as either targeting reductions in enteric methane; reductions in nitrous oxide through manure management; sequestering carbon in pastures; implementation of best animal husbandry and management practices, which would have an effect on most GHG; and land-use practices that also help sequester carbon. Excluding land-use practices, these options have a technical mitigation potential ranging 0.2–2.4 GtCO <sub>2</sub> -eq yr <sup>–1</sup> (Herrero et al. 2016a <sup>[[#fn:r815|815]]</sup> ; FAO 2007 <sup>[[#fn:r816|816]]</sup> ) (Chapters 2 and 6.)

The opportunities for carbon sequestration in grasslands and rangelands may be significant (Conant 2010 <sup>[[#fn:r817|817]]</sup> ), for instance, through changes in grazing intensity or manure recycling aimed at maintaining grassland productivity (Hirata et al. 2013 <sup>[[#fn:r818|818]]</sup> ). Recent studies have questioned the economic potential of such practices in regard to whether they could be implement at scale for economic gain (Garnett et al. 2017 <sup>[[#fn:r819|819]]</sup> ; Herrero et al. 2016a <sup>[[#fn:r820|820]]</sup> and Henderson et al. 2015 <sup>[[#fn:r821|821]]</sup> ). For instance, Henderson et al. (2015) <sup>[[#fn:r822|822]]</sup> found economic potentials below 200 MtCO <sub>2</sub> -eq yr <sup>-1</sup> . Carbon sequestration can occur in situations where grasslands are highly degraded (Garnett 2016 <sup>[[#fn:r823|823]]</sup> ). Carbon sequestration linked to livestock management could thus be considered as a co-benefit of well-managed grasslands, as well as a mitigation practice.

Different production systems will require different strategies, including the assessment of impacts on food security, and this has been the subject of significant research (e.g., Rivera-Ferre et al. 2016b <sup>[[#fn:r1447|1447]]</sup> ). Livestock systems are heterogeneous in terms of their agroecological orientation (arid, humid or temperate/highland locations), livestock species (cattle, sheep, goats, pigs, poultry and others), structure (grazing only, mixed-crop-livestock systems, industrial systems, feedlots and others), level of intensification, and resource endowment (Robinson 2011 <sup>[[#fn:r824|824]]</sup> ).

The implementation of strategies presented in Figure 5.11 builds on this differentiation, providing more depth compared to the previous AR5 analysis. Manure management strategies are more applicable in confined systems, where manure can be easily collected, such as in pigs and poultry systems or in smallholder mixed crop-livestock systems. More intensive systems, with strong market orientation, such as dairy in the US, can implement a range of sophisticated practices like feed additives and vaccines, while many market-oriented dairy systems in tropical regions can improve feed digestibility by improving forage quality and adding larger quantities of concentrate to the rations. Many of these strategies can be implemented as packages in different systems, thus maximising the synergies between different options (Mottet et al. 2017b <sup>[[#fn:r825|825]]</sup> ).

See the Supplementary Material Section SM5.5 for a detailed description of livestock mitigation strategies; synergies and trade-offs with other mitigation and adaptation options are discussed in Section 5.6.

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'''Technical supply-side mitigation practices in the livestock sector (adapted from Hristov et al. 2013b; Herrero et al. 2016b and Smith et al. 2014).'''
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Technical supply-side mitigation practices in the livestock sector (adapted from Hristov et al. 2013b <sup>[[#fn:r1448|1448]]</sup> ; Herrero et al. 2016b <sup>[[#fn:r1449|1449]]</sup> and Smith et al. 2014 <sup>[[#fn:r1450|1450]]</sup> ).

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