Feasible Strategies for Enteric Methane Mitigation from Dairy Animals

Abstract

Methane (CH4), one of the major greenhouse gas (GHG), has a warming potential 25 times greater than carbon dioxide. Agriculture contributes 50% and 60% of all anthropogenic CH4 and nitrous oxide (N2O) emissions, respectively, accounting for 10%–12% of total world anthropogenic GHG emissions. Enteric methane impacts significantly to global GHG emissions for approximately 15% of global warming arising from animal agriculture. Ruminants are the most significant emitters of enteric methane among livestock. About 80 million tons of enteric CH4 are produced annually by livestock around the world. Enteric CH4 emissions are produced by microbial fermentation of feeds in the rumen, and the lower digestive tract represents a gross energy loss from 2% to 14%. Methane production and emissions from ruminants are rising day by day as the world’s ruminant population grows, helping to meet the nutrient demands of the hurriedly expanding human population. Thus, CH4 reduction in ruminants has emphasized both economic and environmental benefits. Many mitigation strategies are reviewed for CH4 abatement from ruminant productions, mainly focusing on animal management, diet selection, rumen manipulation, supplementation of fats, organic acids, oils, plant secondary metabolites, dietary feed additives, defaunation, probiotics, etc. These nutritional amendments also improve feed utilization efficiency, so they are more likely to be accepted by farmers. Nevertheless, no sustainable mitigation techniques have been established yet. To significantly reduce methane emissions from ruminants, a combination of diverse CH4 mitigation methods should be implemented at the farm level. Therefore, a further comprehensive study is needed to investigate proven and effective CH4 mitigation strategies that are both practical and cost-effective while also enhancing ruminant productivity. This paper reviews current management practices and dietary strategies to reduce CH4 from livestock production while improving production and focuses on research issues and the necessity for a systems approach to assessing the relative benefits of abatement options.KeywordsZoonotic pathogensOrganic fertilizerBio-aerosolsBerotoxinsCryptosporidiosisToxoplasmosis