Who thinks of cows when you mention greenhouse gas emissions?? Most people think of industrial businesses and factories. Belches from livestock animals such as cows contain methane which is about 25 times more effective then carbon dioxide as a greenhouse gas. But Alexander Hristov, Penn State professor of dairy nutrition explains in a recent article about the correlation.
"Yes—in fact, the Environmental Protection Agency estimates that cattle belching and manure management contribute about 28 percent of all anthropogenic methane emissions in the United States," says Alexander Hristov, Penn State professor of dairy nutrition. "However, in the big picture of global greenhouse gas emissions, cows are a relatively small player."
"Methane gas is a natural by-product of the complicated bovine digestive process, Hristov explains. As cattle feed makes its way into the largest compartment of the cow stomach, called the rumen, it is feasted upon by microbes and begins to ferment. The fermentation process breaks down the fibrous cattle feed, helping cows get nutrition from otherwise indigestible grass and hay—but also produces lots and lots of gas in the process. Methane makes up somewhere between 20 and 40 percent of the mix."
Despite methane's potency, "As a proportion of all greenhouse gases emitted in the United States, livestock belches only contribute about 2.2 percent," notes Hristov. "The emissions from the energy and transportation sectors are much larger. In fact, looking at methane emissions alone, there are other human activities with larger methane footprints than livestock, such as emissions from landfills, for example."
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