Greenhouse Gases and Animal Agriculture: Extent of Problem and Controls

The livestock industry is a major contributor of greenhouse gases (GHG) in the U.S. Enteric fermentation accounted for methane emissions of 114.9 Tg CO2 equivalent from livestock in 2001. Livestock manure methane emissions were 39.0 Tg CO2 equivalent and nitrous oxide emissions were 58.0 Tg CO2 equivalent. The largest source of GHG emissions from manure was beef, followed by dairy and swine. Anaerobic lagoons contributed the most to GHG emissions from dairy cattle manure. The largest source of GHG emissions from swine manure was from deep pits followed by anaerobic lagoons. Covering of anaerobic lagoons and utilizing the gas is one technology that can be used to reduce methane emissions. Reducing the nitrogen excreted in the manure through diet manipulation will reduce nitrous oxide emissions.