Burping cows add to climate change; feeding them oregano might help
When cows and other ruminants digest their food, methane builds up in their rumen, the largest chamber of their four-chambered stomach. Releasing that greenhouse gas -- mostly by belching -- accounts for 20 percent of all methane emissions in the United States, according to the Environmental Protection Agency.
That's a problem, because methane is a far more powerful contributor to climate change than, say, carbon dioxide, since it prevents more heat and radiation from escaping into space.
An agricultural scientist thinks he has a solution: oregano.
Alexander Hristov, a professor of dairy nutrition at Pennsylvania State University, says that oregano-supplemented feed can reduce a dairy cow's methane production by up to 40 percent, while increasing its daily flow of milk by close to three pounds. (That's a lot, he says, about 5 percent of the average U.S. cow's production.)
In a preliminary trial, Hristov's researchers scooped out the contents of a cow's rumen -- through a surgically made hole in the animal's side -- and incubated samples of it with more than 200 separate plant materials. The researchers then measured the methane produced by each sample to see which plant product most effectively suppressed methane.
"We found that the oregano is just about the only [plant material] that has a substantial effect on methane reduction and doesn't suppress bacterial fermentation," Hristov said.
Replicating the lab results in an animal was a little more complicated. "The animal is a lot more dynamic system," Hristov said.
With a graduate student, Jessica Tekippe, Hristov analyzed methane taken from the rumen of eight cows, four of which had been given an oregano supplement in their feed, four of which had not.
"We took oregano to the animal," Hristov said, "and we saw a significant drop in methane production and an increase in milk yield."
Using a gas chromatograph mass spectrometer to separate and analyze the gas mass in the rumen, they confirmed the lab results and determined that oregano suppresses methane production by 40 percent.
"The large effect on methane production we observed in the animal experiment was quite surprising," Hristov wrote in an e-mail.
Hristov is trying to replicate his results and exploring how the oregano affects milk flavor and taste as well as manure odor.
-- Leslie Tamura