Just as people plagued by flatulence have turned to diets and supplements for relief, scientists are seeking a cure for belching — and sometimes farting — cows.

The stakes are far higher with cows than with humans passing gas in public, though. Cows and other types of ruminants emit methane as their digestive systems break down the grasses or other foods they consume. Add up all the cows in the United States, or those in nations like India or China, which are consuming greater amounts of meat, and you have a significant contributor to global warming.

Though methane breaks down more quickly than carbon dioxide, it's more efficient at trapping heat in the atmosphere than CO2. That means that pound for pound, according to the US Environmental Protection Agency, methane is 84 times more potent of a greenhouse gas than carbon dioxide over a 20-year period.

Cue the Beano of bovines.

'It is the most promising feeding tool to reduce methane emissions.'

A study published earlier this month in the scientific journal the Proceedings of the National Academy of Sciences builds on a growing body of research that shows a compound called 3-nitrooxypropanol (3NOP) reduces methane production from cows without harming them. Though scientists have studied the compound before, the new research looks more closely at how 3NOP impacts a cow's physiognomy. The study's authors found that the substance affects only methane-producing microorganisms and not bacteria that helps with digestion.

The researchers found that 3NOP reduced methane emissions from cows by 30 percent without risking the health or productivity of the animals, David Yáñez-Ruiz, a researcher for the Spanish National Research Council and one of the study's authors said in a statement.

"It is the most promising feeding tool to reduce methane emissions," he said.

Evert Duin, an associate professor in biochemistry at Auburn University and another co-author of the study, said the next step is securing regulatory approval for the compound that would allow its commercial use in the United States and elsewhere. In addition to a government green light, Duin said convincing farmers and ranchers that they should be supplementing cattle feed with 3NOP might be an obstacle.

Alexander Hristov, a professor of dairy nutrition at Pennsylvania State University, said he doesn't know how much the compound might cost, but farmers and ranchers must be convinced that it's worth the expense. So far, at least, there's no evidence that the compound impacts a cow's weight or milk production — and by extension a producer's bottom line.

Hristov authored a previous study that showed methane emissions dropped by nearly a third, when roughly a gram of the compound was added to an animal's feed. Milk production, feed intake, and digestion remained normal among the 48 milk-producing cows that were given the supplement over 12 weeks. And the cows actually gained weight.

In India, scientists are studying a breed of miniature cow that produces one-seventh as much manure and one-tenth as much methane as a typical cow, according to The New York Times. And a Danish research team is testing whether oregano can curb cow burps on organic farms, NPR reported.

Hristov said researchers at Penn State are now looking at whether the compound can improve an animal's health or cause a cow to yield more milk. But even without those assurances, 3NOP is the only technology that has significantly reduced methane emissions, he said.

"If it's applied universally, and it can be applied for most production systems in the world, then you can have a dramatic decrease in methane emissions from the livestock sector," he said.

Success in reducing methane emissions from agricultural sectors in countries like India and China is crucial. As those countries' populations — and their prosperous middle classes — grow, so too do the amounts of meat-based protein they consume.

India's cattle herd consists of more than 190 million cows, according to the Central Institute for Research on Cattle. In the United States, there are nearly 90 million cows, according to the US Department of Agriculture. The digestive processes of animals like cows accounts for about a qurter of the nation's methane emissions.

Roni Neff, director of the Food System Sustainability and Public Health program at the Johns Hopkins Center for a Livable Future, said the world is on course to blow past the internationally agreed upon target of keeping temperatures from rising more than 2 degrees Celsius (3.6 degrees Fahrenheit) compared to pre-Industrial Age levels — and agricultural emissions are partly to blame.

Within the beef industry there's interest in technology that can make meat and dairy production more efficient, she said, but broad support for supplements like 3NOP will depend partly on cost and perceived effectiveness.

But she said she's optimistic that countries can chip away at those emissions by tackling the problem from several angles, including reducing meat consumption in wealthier countries, introducing new strategies to inhibit methane emissions in cows, and better tracking of greenhouse emissions from food production like beef.

"We don't have the luxury to say, 'well, that's not good enough,'" she said. "We basically have to go on all these fronts at the same time."

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