|Rotz, Clarence - Al|
Submitted to: Food and Agriculture Organization of the United Nations Technical Workshop Report
Publication Type: Other
Publication Acceptance Date: 6/12/2012
Publication Date: 1/15/2013
Citation: Hristov, A.N., Oh, J., Lee, C., Meinen, R., Montes, F., Ott, T., Firkins, J., Rotz, C.A., Dell, C.J., Adesogan, A., Yang, W., Tricarico, J., Kebreab, E., Waghorn, G., Dijkstra, J., Oosting, S. 2013. Mitigation of greenhouse gas emissions in livestock production: a review of technical options for non-C02 emissions. Food and Agriculture Organization of the United Nations Technical Workshop Report. p 1-255. Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Animal production is a significant source of greenhouse gas (GHG) emissions worldwide. This analysis was done to evaluate the potential use of nutritional, manure, and animal management practices to mitigate non-CO2 GHG emissions (i.e., methane, CH4 and nitrous oxide, N2O) from enteric fermentation and manure decomposition. Mitigation practices were categorized as enteric CH4 mitigation practices, dietary management and N2O emissions from manure, manure management mitigation practices, and animal management mitigation practices. Nitrates show promise as enteric CH4 mitigation agents, particularly in low-protein diets that can benefit from nitrogen supplementation, but more in vivo studies are needed to fully understand their impact on whole-farm GHG emissions, animal production, and animal health. Ionophores, through their effect on feed efficiency, likely have a moderate CH4 mitigating effect in ruminants fed grain-forage diets. In ruminants fed pasture, the effect of ionophores is not sufficiently consistent to be adopted as a mitigation strategy. Hydrolysable tannins may reduce enteric CH4 production, although intake and milk production may be compromised. Vaccines against rumen archaea offer an exciting mitigation opportunity for the future, but the extent of CH4 reduction appears small and persistence of the effect is unknown. Dietary oils are effective in reducing enteric CH4 emission, but the feasibility of this mitigation practice will depend on its cost-effectiveness and the mitigation potential must be expressed per unit of product (and milk components with dairy production systems) to account for potential negative impacts on feed intake, production, or milk composition. Inclusion of concentrate feeds in the diet of ruminants will likely decrease enteric CH4 emission per unit of product, particularly when inclusion is above 35 to 40% of dry matter intake, but the effect will depend on inclusion level, production response, effect on fiber digestibility, plane of nutrition, feed type, feed processing, and likely animal species. In many parts of the world, this also may not be economically feasible. Increased forage digestibility is expected to increase production and decrease eneteric CH4 production per unit of product. It appears that the introduction of legumes in warm climate regions offers a mitigation opportunity. Forage with higher sugar content (high-sugar grasses or harvested in the afternoon) may reduce urinary nitrogen losses and consequently N2O emission from manure applied to soil, although more research is needed to support this concept. Increasing forage digestibility, intake, and animal production reduces overall GHG emission from rumen fermentation and stored manure and are highly-recommended mitigation practices. Processing of grain to increase its digestibility likely reduces enteric CH4 production per unit of animal product, but caution should be exercised that fiber digestibility is not decreased. This mitigation practice may not be economically feasible in many developing countries, but minimal processing is highly recommended so grain energy is better utilized for animal production. Improving the nutritive value of low quality feeds in ruminant diets can have a considerable benefit on herd productivity while keeping the herd CH4 output constant. Consequentially, CH4 emission per unit of product is reduced. Chemical treatment of low quality feeds, supplementation, breeding, and selection for straw quality are easily applied, but there has been little adoption of these technologies on farms. Feeding protein close to animal requirements, including varying protein concentration with stage of lactation or growth, is recommended as an effective manure ammonia and N2O emission mitigation practice. Low-protein diets for ruminants should be balanced for rumen-degraded protein so microbial protein synthesi