Enteric methane in dairy cattle production: Quantifying the opportunities and impact of reducing emissions

Authors: KNAPP, JOANNE - Fox Hollow Consulting; LAUR, GINA - University Of Wisconsin; Vadas, Peter; WEISS, WILLIAM - The Ohio State University; TRICARICO, JUAN - Innovation Center For Us Dairy

Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2014
Publication Date: 4/18/2014
Citation: Knapp, J.R., Laur, G.L., Vadas, P.A., Weiss, W.P., Tricarico, J.M. 2014. Enteric methane in dairy cattle production: Quantifying the opportunities and impact of reducing emissions. Journal of Dairy Science. 97:3231-3261.

Interpretive Summary: Enteric methane emissions from ruminant livestock such as cattle contribute to greenhouse gases. As part of an ongoing industry-wide effort to reduce these emissions, we conducted a review of scientific literature to take inventory of what the research has already shown. Methane-reducing practices include changing feeding management and nutrition, adding compounds to diets to modify rumen function, genetic improvements to increase animal lifetime production, genetic selection for animals that are more efficient, and management improvements to increase productivity of individual animals and whole herds. Some of these approaches require further research, but many could be implemented now. Past research has focused on identifying and evaluating approaches based on nutrition, feeding, and changing rumen function, and some of these approaches may be able to reduce methane by 5 to 15%. Methane reductions of 15 to 25% can be achieved by combining genetic and management approaches. All approaches should consider the economic impacts on farm profitability and the environmental consequences of feed nutrients ending up in manure and generating greenhouse gases during storage. We concluded that future research should be targeted at improving understanding of rumen microbiology and ecology, nutrient use, and animal health and fertility. Experiments should be more comprehensive in their design to make them as useful as possible to commercial operations. This information will guide scientists and policy makers in determining where future research can have the biggest impact on reducing enteric methane emissions from ruminant livestock.

Technical Abstract: Many opportunities exist to reduce enteric methane emissions per unit of product from ruminant livestock. These include alterations in feeding management and nutrition, addition of compounds to modify rumen function, genetic improvements to increase animal lifetime productivity (including health and reproduction), genetic selection for animals that are more feed efficient, and management improvements to increase productivity of individual animals and, more importantly, productivity at the herd level. Some of these approaches require further research, but many could be implemented now. Past research efforts have largely focused on identifying and evaluating approaches based on nutrition, feeding, and modifications of rumen function, and some of these approaches may be able to reduce methane per unit of product by 5 to 15%. More significant reductions of 15 to 25% methane per unit of product can be achieved by combinations of genetic and management approaches that increase feed efficiency and life-time productivity at the herd level. All approaches to reducing enteric methane emissions should consider the economic impacts on farm profitability and the environmental consequences of feed nutrients ending up in manure and generating greenhouse gases during storage. Research efforts should be targeted at further improving our understanding of rumen microbiology and ecology, nutrient utilization, animal health, and fertility. Experiments should be more comprehensive in their design to enable broader inference of the results and extension to commercial animal feeding operations.