Free-range beef found to emit more methane than sheep
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lion (USD) livestock industry is one A study of the Australian livestock “Although the total amount of of the largest in the world. Slightly industry has found that a kilogreenhouse gases per head of cattle less than half of the output is exgram of sheep meat, by the time is higher for the grain-finished ported. it leaves the processing plant, has beef, this is completely offset by The industry produces 11% of emitted about half as much meththe more efficient weight gain of Australia’s greenhouse gases, most of ane (CH4) as a kilogram of grassthe grain-finished cattle,” adds Peit in the form of enteric ters via e-mail. “This work suggests finished beef and about 25% less methanogenesissthe production of it would make sense, from a greenthan feed-lot-finished beef. house perspective (though “The daily rate at which not necessarily from other sheep and cattle burp is perspectives), to produce all about the same per kilogram beef at feed-lots.” of product, but the cattle do While feed-lots are thus enviit for longer before we get ronmentally quite competitive, their meat,” explains lead organic farms performed best author Gregory M. Peters of in uses of energy and materials. the University of New South “Feed choice and feed producWales in Sydney in a teletion systems are the major phone interview. Cattle are contributors to the environgenerally slaughtered after mental impact in all cases,” the less than three years, which study notes. Meanwhile, “In is about twice the life excontrast to the greenhouse gas pectancy of sheep, he said. results (produced by the aniThe study estimated the mals themselves), the processcarbon footprint and energy Because of the shorter life expectancy of sheep, ing plants contribute most of consumption over two years production of their meat produces fewer greenhouse the primary energy use,” the of three meat supply chains gases than that of beef. study says. in Australia: a sheep meat methane in the digestive tract. About “Whether the reduced enteric supply chain in western Australia, 90% of the CH4 comes from the animethane emissions from a grain an organic beef supply chain in mals’ mouths in the form of burping, diet can provide greater greenVictoria, and a beef/sheep meat according to Ken Casey of Texas house gas savings than those supply chain in New South Wales A&M University in Amarillo. CH4 is caused by the production of the that finished fattening the beef in 25 times more powerful as a greengrain feed, and whether other enfeed-lots. The farms were chosen house gas than CO2. vironmental impacts from grain to be roughly representative of “Our data suggest that organic production such as ecotoxicity three different red meat producproduction may use less energy than potentials will become a concern, tion systems: conventional beef, conventional farming practices but will depend on the production organic beef, and conventional typically results in a higher carbon system,” the study concludes. sheep meat. The conventional footprint,” the authors say. Christopher Weber, assistant beef supply chain produces both The study’s “functional unit” research professor of civil and engrass- and grain-finished beef. was “the delivery of 1 kg of hot vironmental engineering at Carn“It’s the first time a detailed prostandard carcass weight at the egie Mellon University in cess analysis of how three Australian exit gate of the meat processing Pittsburgh, PA, praises the study. farms operate was combined with an plant,” as stated in the article. “There have been many argueconomic-type input/output analysis The authors took into account ments as to the relative sustainof the extended supply chain,” Peters that because grain is more digestability of these beef production says of the article (Environ. Sci. Techible than grass, the weight acmethods, and confirming the nol. 2009, DOI 10.1021/es901131e). quired by cattle on feed lots higher carbon footprint of grassPeters is leaving the School of Civil produces less CH4 than the finished beef is an important conand Environmental Engineering to weight put on cattle eating grass. tribution,” he writes in an e-mail. take up a position at the University “While our results show a 38% “It is particularly nice to see a of Gothenburg, Sweden. reduction in enteric methane emisstudy using primary data from a With 86 million heads of sheep sions for grain-finished beef, other large exporter of beef.” (two-thirds sold as lamb and onethird as mutton) and 31 million studies claim reductions as great as —CHRISTOPHER PALA heads of cattle, Australia’s $13.7 bil70%,” the authors comment. 9 ENVIRONMENTAL SCIENCE & TECHNOLOGY / February 15, 2010
10.1021/es903889f
2010 American Chemical Society
1158
Published on Web 01/12/2010
