Methane, nitrous oxide emissions and mitigation strategies for livestock in developing countries: A review

Methane (CH4) and nitrous oxide (N2O) are two important greenhouse gases (GHGs) that are emitted into the atmosphere by livestock during the process of enteric fermentation and manure management. Developing countries produce a large quantity of those emissions, caused mainly by inefficient animal rearing systems, feed production and manure management. This paper outlines the CH4 and N2O emitted from livestock in developing countries and the mitigation actions that could be put in place to reduce atmospheric emissions and increase animal productivity. Emission intensity expresses emission (CO2 equivalents) per unit of product and describes it in relation to the capacity of local animals to produce from local resources. Developing countries are characterized by low production per animal and, consequently, high emission intensity. The emission intensity of dairy cattle in developing countries ranges from 2 to 9 kg CO2-eq/kg fat and protein corrected milk (FPCM) and in only a few cases is below 2 kg CO2-eq/kg FPCM. In sub-Saharan Africa, the average emission intensity is 7.5 kg CO2-eq/kg FPCM for dairy cattle, 71 kg CO2-eq/kg of carcass weight for beef cattle, 6.9 kg CO2-eq/kg FPCM for sheep and goats, and 5 kg CO2-eq/kg eggs for chickens. Taking into account the limited economic and technical resources in most developing countries, the application of appropriate mitigation tools is recommended to reduce the emissions of CH4 and N2O gases in the atmosphere. Increasing livestock productivity through selection and feeding is the most effective tool to reduce emission intensity.