Farting Cows Target of Focused Breeding to Limit Methane Emissions

What could be more natural than a cow or a sheep? What could be more pristine (except to the human sense of smell)? Yet such livestock are major contributors to the greenhouse gases that are widely blamed for global climate change.

Gasoline-powered cars and coal-fired power plants, which emit carbon dioxide, certainly are major contributors to air pollution, but in recent years it's been shown that farm animals and even babbling brooks also are to blame because they emit methane, or CH4, which the EPA says has a 20 percent larger impact on the environment than CO2 does.

Now researchers have isolated genes and gut microbes that contribute to these emissions from livestock, a finding that could help them understand why some sheep, for example, emit more gases than other members of the same species.

The U.S. Environmental Protection Agency (EPA) says global volume of methane has increased by an estimated 50 percent since the industrial revolution began in the early 19th century.

But how to lower these "natural" methane emissions? A study by the Joint Genome Institute (JGI) at the U.S. Energy Department and New Zealand's AgResearch Limited's Grasslands Research Center has shown that something called "focused breeding" can produce animals who produce far less methane.

The JGI observed that some livestock produce prodigious levels of methane, while others produce hardly any. Sheep, notorious for belching great volumes of methane, are especially problematic, especially in New Zealand, where they outnumber human beings by seven to one.

The U.S. and New Zealand researchers studied the differences between high- and low-emission sheep, and found the sources of the noxious gas: microbes in the animals guts. And they discovered something more important: a likely solution to the problem. In a statement, JGI Director Eddy Rubin said it's how the animals' digestive tracts react with the microbes, and that breeding can change this reaction.

The screening and breeding sheep already has begun, and the U.S.-New Zealand team says the hope is that eventually such livestock will be more plentiful, and less offensive, farm denizens.