You may have heard about this research challenge in recent years: Scientists are looking for ways to reduce the amount of methane that cows release into the air through burping and flatulence. You probably chuckled as you read it.
But it’s a serious matter and a national environmental priority. The nation’s 89 million cows — along with a much smaller number of sheep — are responsible for 25% of the nation’s yearly methane emissions, second only to oil and gas production, according to the U.S. Environmental Protection Agency. That’s equivalent to the amount of greenhouse gases emitted by 650 million cars.
Carbon dioxide is the most prevalent greenhouse gas contributing to the climate crisis and stays in the atmosphere for thousands of years. Methane, on the other hand, usually breaks down in about 12 years, but its warming power is much more potent — about 25 times that of carbon dioxide — during that relatively short time frame.
The United States is among more than 150 countries that have signed the United Nations’ Global Methane Pledge to reduce methane emissions by at least 30% by 2030. Reducing emissions from cows and other livestock is considered crucial to meeting that goal.
Of the estimated 350 pounds of methane a single milk cow releases in a year, flatulence accounts for only a tiny fraction of it — 3.5%, or about 12 pounds. The rest comes from belching as the cow chews.
“Basically, everyone now is on the methane bandwagon,” said Alexander Hristov, a Penn State University distinguished professor of dairy nutrition and one of the world’s leading researchers into reducing methane emissions from livestock.
“If you commit to being carbon neutral, then you have to look at livestock operations. There’s no other way. If you want an immediate effect on greenhouse gases, you want to target methane, not carbon dioxide,” said Hristov, who is the editor of a new book, Advances in Sustainable Dairy Cattle Nutrition.
After nearly two decades of experimenting with feed supplements that alter the fermentation process inside cows’ four-chambered stomachs, the federal government is spending millions to wrap up proof on a couple of promising solutions.
The finalists: a synthetic feed supplement known as 3-NOP that studies have found to reduce methane emissions in cows 25-29%, and a red seaweed found in tropical oceans that studies have shown can reduce methane by as much as 63% — though in some studies, the seaweed-eating cows ate less feed overall and produced less milk.
If either or both of these methane inhibitors are embraced by the government, the dairy industry and consumers, the focus will be on integrating them with the nation’s 9.4 million dairy cows — because feed additives would be impractical with pasture-grazing beef cattle. Roughly 1.2 million of those milk cows are in Chesapeake Bay watershed states, primarily New York and Pennsylvania.
Over the last decade, scientists have searched far and wide for natural and synthetic feed additives that could inhibit microbial methane production in cows’ complex stomachs. The tinkering included plant extracts, vegetable oils, flax seeds, linseeds and oilseeds, garlic and capsaicin from chili peppers. Researchers have also experimented with chemically treated forage grasses and different grass species, as well as the selective breeding of cows that produce lower methane amounts, and even a one-time vaccine.
Hristov is intimately familiar with most of that research. Since 2005, he and his Penn State cohorts have explored those avenues on lactating cows at the university’s 500-head livestock farm.
Through repeated testing, almost all the ideas were found to have drawbacks, including digestive side effects, reduced milk production, lower fat content in milk, inhibited weight gain, costliness and other problems.
Now, the U.S. Department of Agriculture has awarded Hristov and his team a $2 million grant for a three-year study of whether the red seaweed and 3-NOP supplement can be continuously effective in bringing down methane emissions.
The proposed methane-reduction options also are part of a larger $25 million grant to Penn State from the USDA to help Pennsylvania dairy farmers use more climate-smart practices while also boosting the value of their products.
How might the added cost of feed supplements offer financial benefits to dairy farmers already struggling to make a profit?
For one thing, the 3-NOP feed additive was found to increase fat in milk, which is desirable for making cheese and butter. Also, because producing methane is a biological waste of energy in a cow, inhibiting it enables cows to gain weight faster, studies showed — and heavier cows produce more milk. Dairies also might be able to sell carbon credits for reducing methane emissions.
And, at the other end of the supply chain, consumer surveys have shown that the public is willing to pay more for milk, cheese and butter if they know they are aiding the environment.
Hristov said that the 3-NOP compound he helped develop will likely be the most effective weapon for reducing methane from cows.
The feed additive is already being produced by a Dutch company, Royal DSM, under the brand name Bovaer. It has been approved for use in 42 countries, though not yet in the U.S.
Bovaer can be a game-changer, Hristov said, but he has two lingering concerns. One is that some studies suggest a cow’s stomach may adjust over time and scale down the additive’s ability to reduce methane.
The other is that consumers may be wary of a synthetic compound finding its way into their milk, cheese and butter, no matter how safe it is found to be.
He thinks red seaweed is a far less likely solution. For one thing, cows don’t seem to like the taste, he said. And there’s not enough of it for wild harvesting to be practical. Widespread use would require large aquaculture operations.
“But [that drawback] flies under the radar because it’s a catchy thing,” he observed. “Feeding seaweed to cows. That resonates with some people very well.”