A small but deadly greenhouse gas: how to reduce methane emissions from livestock

Methane (CH4) is a well-known greenhouse gas (GHG) with a global warming potential 28 times that of carbon dioxide (CO2). The agricultural sector contributes significantly to anthropogenic (human-caused) CH4 production, although estimates vary depending on calculation method. The consensus states that the agricultural industry contributes somewhere between 7 and 18% of total anthropogenic GHGs and around 6% of total CH4 emissions. The breakdown of plant material in the rumen (enteric fermentation) constitutes approximately 87% of total agriculturally produced CH4. This CH4 production from enteric fermentation also represents a loss of energy for the animal (up to 12%) which could otherwise be used for growth or milk production. It is therefore not only crucial for the benefit of the environment and in climate change mitigation to reduce CH4 emissions, but also to increase the production efficiency of ruminant livestock. Ruminants themselves are not the only producer of CH4 on the farm, with manure/waste, farm vehicles and machinery and animal feed production also making a contribution.