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When you think of greenhouse gas emissions, you probably think, "Ah, it's all the cars people drive, that's what contributes to the greenhouse effect!" That's what most people believe about greenhouse gases and air pollution, anyway. But did you know that the major contributor to greenhouse gases comes from the gastrointestinal emissions of ruminant animals like cows and sheep?
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That's right, folks. Cow and sheep burps and farts generate most of the methane that makes up the greenhouse gas in our atmosphere. The construction of a ruminant animal's digestive tract is slightly different than that of other herbivores in that there is a chamber known as a rumen where fermentation of food matter takes place. Many bacteria, fungi, protists and viruses inhabit the rumen, and most of these play a role in helping the animal to digest plant fibers. When these fibers are digested, a great deal of methane and carbon dioxide are produced, which make it into the atmosphere through eructation and release of flatus (the scientific ways to say 'burp' and 'fart'). The amounts of the various gases emitted depend on the diet eaten by the animal. A diet rich in grain causes cows to produce less methane, while a diet rich in hay and other grasses produces large quantities of methane.
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Stephen Moore of the University of Alberta has a two-pronged approach to solving this problem. Moore and his colleagues have studied selective breeding in cattle as well as genetic modification of feed crops as a way to potentially reduce methane emissions by cows. Moore posits that if the feed cows eat is modified so that it causes the cow to release less methane that perhaps overall greenhouse gases may be reduced in the atmosphere. Moore and his colleagues have also identified several regions of the bovine genome that regulate immune system activity, which helps determine what microbes can inhabit the rumen. This is important since you should note that it is the microbes that produce the methane, not the cow itself. But the cow can regulate what microbes live within its rumen by modulation from the immune system. Then, by selectively breeding cattle that naturally release less methane from the foodstuffs they eat, Moore believes that methane emissions can be drastically reduced.
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This is an incredible discovery, but it is not without its problems, which lie chiefly with the cost to farmers and ultimately, consumers. To produce both cattle and crops that are genetically engineered, a large amount of money must be invested in the biotechnology companies responsible for developing these organisms. The costs of this investment are ultimately passed on to farmers, who must purchase these organisms. Then the costs are passed along to the consumer when the organism or any product from the organism is produced, such as milk or meat from the cows.
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Another issue that is a thorny one is the issue of whether people would consume products from genetically modified animals. It has already been demonstrated that many people worldwide are resistant to the idea of eating cloned meat. Even though the US Food and Drug Administration has declared cloned meat and milk safe to eat and drink, a majority of people are not convinced. Might this prejudice against cloned organisms for consumption extend to genetically modified organisms as well? Even if the organisms in question are being modified in an effort to mitigate a global problem--greenhouse gas emissions--should public opinion on GMO's get in the way of solving this problem?
Posted by scienceguru on May 21, 2009
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