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– Peaches, a brown-and-white Jersey cow weighing 1,200 pounds, was amiably following Edward Towers through a barn when the 6-year-old dug in her front hooves.

Towers, a 28-year-old-farmer whose family owns Brades Farm, near Britain’s rugged Lake District, leaned into Peaches until she finally stepped through a metal gate that would hold her head still for an exam.

Deepashree Kand, a scientist studying animal nutrition, stepped forward with a device about the size of a grocery-store scanner. She pointed a laser at the cow’s nostril and waited for Peaches to belch.

Kand’s employer, a Swiss company called Mootral, is studying whether an altered diet can make cattle burp and fart less methane — one of the most harmful greenhouse gases and a major contributor to climate change. If they were a country, cows would rank as the world’s sixth-largest emitter, ahead of Brazil, Japan and Germany, according to data compiled by Rhodium Group, a research firm.

It is a well-known problem that has had few promising solutions. But in the past five years, a collection of companies and scientists has been getting closer to what would be an ecological and financial breakthrough: an edible product that would change cows’ digestive chemistry and reduce their emission of methane.

Several companies are pursuing a seaweed-based compound, and a Dutch firm, DSM, is testing a chemical supplement. Mootral is one of the furthest along. By mixing compounds from garlic, citrus and other additives into a pellet that’s mixed with a cow’s diet, the startup has surprised scientists by significantly cutting the toxic output of animals like Peaches.

The findings were consistent with the those of several peer-reviewed studies. Trials are underway in the U.S. and Europe. The product is being tested at dairy and meat farms, including a Dutch farm used by McDonald’s for studying new techniques in its supply chain. Venture capitalist Chris Sacca, who became a billionaire with early bets on Uber and Twitter, has invested.

Many questions remain. Mootral must prove that its product works on different breeds of cows and in different climates.

Its business model depends on convincing typically conservative livestock and dairy companies that they will receive credits they can sell in the unpredictable and largely unregulated carbon-offset market for using what is basically Gas-X for cows. But if Mootral or one of its competitors can hold up at scale, the result could be one of the simplest and fastest ways to cut a major source of greenhouse-gas emissions.

“It is something, to be honest, that I never expected,” said Gerhard Breves, a longtime livestock researcher in Germany who performed one of the first independent tests of Mootral’s product.

Cows are a digestive miracle. Inside their stomach is an oxygen-free environment with a steady temperature, similar to the fermentation tanks used to make beer. Microbes decompose and ferment materials like cellulose, starch and sugars. Cows can eat just about anything — grass, hay, cornstalks, rapeseed — and turn it into energy for producing milk and meat.

But methane is a main byproduct of the enzymes that help break down the food. The gas can’t be turned into energy, so as it builds up, a cow must expel it. There are about 1.4 billion cattle globally, each emitting the equivalent of 1.5 to 2.5 metric tons of carbon dioxide each year, roughly half the output of an average American car.

As awareness of cattle’s environmental impact has reached the mainstream, the meat and dairy industries have felt the effects. Sales of alternative milks and meat substitutes have soared. Vegetarianism and veganism have spread.

“This is an existential threat,” said Joe Towers, Edward Towers’ older brother, who also works at Brades Farm. “Farmers are keen to improve and show they aren’t the bad guys.”

Mootral’s main research lab is at the base of a lush valley, in a former coal-mining region of Wales. The company’s work on cows dates to 2010, when a group of researchers participated in a European Union research effort to explore ways to reduce methane from cattle.

The team, working for a company called Neem Biotech, had studied garlic’s antimicrobial properties in humans. In lab trials, the scientists found that it also reduced methane in cows thanks to allicin, the same strong-smelling compound that’s produced when a garlic clove is cut with a knife. But the work didn’t go any further.

In 2012, Neem was sold to a life sciences company, Zaluvida, whose founder, Thomas Hafner, intended to work on drugs for people. But during a review of research, a colleague found the methane work in a computer file named “Mootral.” It explained how allicin interacted with microbes inside a cow’s stomach.

Allicin is volatile, and the team struggled at first to come up with a consistent blend that would work across members of a herd of cattle. They’re still tweaking the formula. At one point, scientists improved results by adding a trace amount of citrus from Spanish oranges. New additives like seaweed and other different kinds of garlic are being tested.

By 2017, Mootral was confident enough in its work to ask outside scientists to perform their own trials. That year, researchers in Denmark and Germany published findings saying the company had reduced cows’ methane emissions more than 50% in lab simulations. In Mootral’s first tests in dairy cows on a fully functioning farm, Brades, methane emissions fell 38%. A California study found a reduction of about 20% in meat cattle.

Sixteen tests and studies are scheduled once work stoppages from the coronavirus lifts, including at Purdue University and the University of California, Davis, Hafner said. The Swiss and Irish governments are funding Mootral research.

There have been unexpected results. Researchers have shown an increase in milk production, possibly because cows that expend less energy expelling methane produce more dairy. The farmers at Brades said flies weren’t bothering their cows as much, perhaps as a result of garlic breath.

Many scientists need more convincing. Hanne Hansen, who performed an early lab test on Mootral and is an associate professor at the University of Copenhagen’s department of veterinary and animal sciences, said more published research was needed to prove the food additive would work on different breeds and in various climates. Much of the research, she said, has been performed in labs that only simulate the chemistry of a cow. Mootral also hasn’t been tested on cows at large industrial farms, like those in the United States, which are notorious hubs for methane emissions.

“What happens in the laboratory is not always what happens in real life,” Hansen said. “Mootral has potential, but we need to see more proof.”