The collective breathing of cows accounts for nearly 20 percent of the methane gas released into the atmosphere. To cut down on the 100 to 150 gallons of the gas that a typical cow accounts for each day, University of Nebraska researchers are developing an additive for cattle feed.
"The reason we're focusing on methane is because it's a short-lived, highly potent greenhouse gas that needs to be reduced," said biochemistry professor Stephen Ragsdale.
The methane produced in a cow's rumen, the first of a cow's four stomachs, gets into the bloodstream and exits through the lungs, said Ken Olson, a range livestock nutritionist at Utah State University. Almost all of it comes from breathing, though a tiny bit does escape when a cow belches, Olson said.
Olson conducted a six-year study that found better range management practices like providing higher quality forage could make a small difference in the amount of methane released by cattle.
In Nebraska, it's been three years since Ragsdale and fellow researchers James Takacs and Jess Miner had the idea of reducing methane by blocking enzymes in the cow's rumen that are necessary to produce it.
That compound would be delivered in an additive to cattle feed, a process the researchers have patented. They are now working with a commercial partner to develop a viable formula.
They have tested over 200 compounds in the last 18 months, trying to find the right formula that blocks the methane but doesn't harm the beneficial microbes in the cow's rumen.
From those, 10 have been successful enough to be tested on rumen fluid extracted from a steer.
"Of those, about 20 to 30 percent are indeed doing what we expect them to do," said Ragsdale. "We're honing in on what would be perfect."
They have not yet tested any compounds in live animals, and Ragsdale wouldn't speculate on when that would happen. It likely will be in an animal much smaller than a cow.
"We'd probably go to sheep before cattle, and before sheep we may go to a termite," he said. "They make a lot of methane."
Human activities — like cultivating livestock — have in the last 200 years altered the chemical composition of the atmosphere through the buildup of greenhouse gases, primarily carbon dioxide, methane and nitrous oxide.
Those gases are widely seen as contributing most to global climate change. They trap some of the outgoing energy from the Earth, retaining heat not unlike the glass panels of a greenhouse.
The Earth's surface temperature has risen 1 degree in the last 100 years, said Gregory Symmes with the National Academy of Sciences.
The Nebraska researchers know they won't eliminate all of the methane emissions from cattle. They are hoping to reduce them by about 4 percent, which would help restore some equilibrium to the planet's natural method of getting rid of methane from its atmosphere.
Methane's lifetime in the atmosphere is about 10 to 12 years, compared to 50 to 200 years for carbon dioxide. Focusing on reducing methane would provide quicker benefits to reducing the greenhouse gases.
A 4 percent reduction would be small but welcome, according to a former senior scientist at the National Center for Atmospheric Research.
"Any time you can make a reduction, sure it's going to help. But it's not going to solve our problems with global warming," said Patrick Zimmerman, now the director of the Institute of Atmospheric Sciences at the South Dakota School of Mines and Technology in Rapid City.
The Nebraska researchers expect another side benefit to cutting methane production by cattle. They believe methane does nothing beneficial for the animals, and up to 16 percent of the feed given to cattle is wasted because it goes to produce methane.
If methane production drops, producers would have to feed the cattle less because more of the animal's energy is going to its own production of proteins, amino acids and fat.
"All the things that the livestock producer values in their beef," Ragsdale said.