Current and emerging technologies for decreasing enteric methane emission from individual ruminants

The quantity of enteric methane emitted per unit of ruminant animal product can readily be reduced by altering breed, nutrition and animal management in ways that decrease the maintenance fraction of consumed energy. In contrast, there are currently few practical means of reducing daily enteric methane emissions from individual animals without compromising productivity. Feed additives such as oils and organic acids are often effective but are limited to intensive feeding situations, which contribute little to national emissions. Methods for reducing individual emissions from extensively grazed livestock are not currently available. However, several strategies that may result in stable and low rumen methane production in extensively grazed livestock are under development. Genetic means of addressing this problem are also being evaluated, but progress will be slow. Future adoption of such technologies will be subject to the relative economic values of methane and other animal products.