Professor Cuts Cow Methane

Sep 23, 2010

Penn State professor Alex Hristov with the cows he's been feeding a diet heavy in oregano.
Credit Emily Reddy / WPSU

It’s feeding time at an experimental dairy barn not far from Beaver stadium. A big square machine on wheels spits a pile of hay in front of each cow on one side of the barn, and lab assistant Chan Hee Lee pours a bucket of dried green leaf bits on top.

As the feeding machine finishes up and rolls out of the barn, Alex Hristov says they tried a lot of things before they found oregano reduced cows’ methane output.

“We started with essential oils,” Hristov said. “Lavender, mint. Citrus, onion, anything, you name it.

So why is Hristov focused on cutting methane?

Well, while burning fuel for transportation or powering homes and businesses are the biggest culprits, farm animals create greenhouse gases, too. And they’re especially big producers of methane. So cutting cow methane emissions helps the environment. About a fifth of methane produced in the United States comes from cows.

And if you’re picturing cows being fed hay spiked with oranges….and then put in a big glass box to trap their gases …don’t. Hristov says these early tests were done on cow stomach juices in the lab.

“We cannot test 200 or 500 or 100 even compounds on cows,” Hristov said. “That’s why we do these tests in the lab, first. This is what we call a screening test.”

And as an important side note, cutting methane actually means more milk.

“In the trial we’ve conducted here,” Hristov said, “there was three pounds increase in milk yield, which can be explained easily by reduced methane. So if we save energy from methane, that energy can go into milk.”

In all, Hristov and his crew tested more than 200 plants, essential oils, and compounds before they discovered the impact of oregano.

“And the oregano was the one that consistently came on top with reducing methane, but not affecting fermentation, because that’s critical,” Hristov said.

It’s critical that fermentation continue in the cow’s stomach because without it cows wouldn’t be able to digest food. Some of the substances Hristov tested cut down on methane output, but they also cut fermentation. To make sure that’s not happening with the oregano in the live animal tests, Hristov’s team takes regular samples from the cow’s stomachs.

“We want to make sure that we don’t effect negatively anything else, but just drop the methane down,” Hristov said. “It would be nice if we improve fermentation, increase digestibility, for example.

A different test tomorrow will measure methane levels. There’s still no box to put the cow in to collect gases, which mostly come in the form of belches, by the way. Instead they’ll suck the gases out through a tube and put them in a vacuum bottle for testing.

Hristov says the end goal is not to feed oregano to millions of cows.

“I don’t know if feeding oregano to 9 million cows in the US is going to be practical,” Hristov said. “The end goal is to see what in the oregano has this effect and use these compounds to inhibit methane.”

So far Hristov has found methane reductions of 40 percent with oregano. There aren’t currently any limits on methane production by livestock. But there are laws capping nitrogen runoff from farms. And Hristov says he expects methane restrictions are on the way. He hopes his research will help prepare farmers if and when those regulations are imposed.