Report 2 - Enteric Methane Review

Abstract

Methane is a potent greenhouse gas. In Australia, only about 11% of national emissions of methane are produced by sheep and cattle, but enteric methane emissions attract media attention and a disproportionate and undeserved amount of blame for global warming is directed at ruminant livestock. Media fascination with 'animal farts' and enteric methane has in turn helped to generate negative social perceptions of the red meat industries. Some strategies for reducing enteric methane emissions and arguments that could help redress these negative perceptions are included in an Appendix to this report. After 2015, calculations of methane emissions from ruminants may be included in carbon accounting schemes and, if this occurs, will place financial imposts on the grazing industry. Proposed methodologies that could be used to measure methane emissions from livestock in Australia are considered along with inventory systems in overseas countries. Current knowledge of the microbiology and biochemistry of the rumen and the reasons why methane is produced by ruminants are reviewed, along with proven and potential ways to reduce methane outputs at an individual animal, or farm, or national level. Currently available strategies that reduce methane emissions are described, along with potential strategies that need further research and development.