海角大神

On the campus of Cornell University, within an intricately monitored and carefully sealed chamber, there is a cow.聽

Scientists carefully record what this cow eats and what she drinks. They open the chamber only once a day, so as to limit disturbances to her environment. Every breath she takes 鈥� or more crucially, exhales 鈥� is also measured to its molecular level. There is hydrogen. There is carbon, recorded down to its isotopic composition. There is oxygen.聽聽

And, most important to this state-of-the-art study, there is methane.

Methane is a naturally occurring gas that comes from a variety of biological and industrial sources, from oil- and gas-well leaks to decomposing garbage to, well, cow burps. It is also one of the world鈥檚 most potent greenhouse gases 鈥� far more heat-trapping than carbon dioxide. And although it lasts for a much shorter time in the atmosphere than carbon dioxide, methane has been getting increasing attention by those looking to fight climate change.

鈥淭here is growing awareness amongst environmental advocates, policymakers, that reducing methane emissions is the fastest way to reduce warming,鈥� says Dan Blaustein-Rejto, director of food and agriculture at the nonprofit Breakthrough Institute.

And that attention has started to focus on cows. Cows such as Number 2945, who is standing in the middle of one of Cornell鈥檚 new respiration chambers.聽

Although exact percentages are difficult to determine, researchers estimate that cows are responsible for around 30%聽of U.S. methane emissions. This is largely because cattle, like goats or sheep, are ruminants: animals with four-chambered stomachs that ferment grass and other vegetation into consumable food. And a natural by-product of rumination is methane.

Although it is a natural system, this methane production of cows has become a problem, in large part because of cattle population numbers. In short, the world has an awful lot of cattle, which translates to a lot of emissions. 聽

According to the U.S. Department of Agriculture, there are 28.2 million beef cattle in the U.S., along with 9.36 million dairy cows and 33.6 million calves. And those numbers pale in comparison to countries such as India, which has an estimated 61 million milk cows, or Brazil, with around 234 million beef cattle.聽

With growing pressures from policymakers and climate advocates, then, agribusiness and scientists are trying to figure out how to make individual dairy cows more productive, which could lead to smaller herds, while at the same time trying to find ways to make cow burps 鈥� the body function that produces the most methane 鈥� less gassy.

How much methane do cows produce?

The first step to doing that, says Cornell associate professor Joseph McFadden, is to get good measurements of bovine methane in the first place. Without having an accurate baseline, it鈥檚 hard to know how effective a proposed solution is 鈥� whether a feed additive, a vaccine, or even gene sequencing.

鈥淚f you鈥檙e going to pay a farmer to reduce emissions by 30%, that requires inventory data,鈥� he says. 鈥淵ou have to work with farmers to figure out how much methane is produced today, how much tomorrow.鈥澛�

But measuring bovine methane is easier said than done.聽聽聽

鈥淭his is a biological process,鈥� says Mr. Blaustein-Rejto. 鈥淐attle are not machines. Every animal functions a little differently, just like every person has a different microbiome and digests food differently.鈥�

The methane production also changes based on where cows live, how old they are, and what they eat. But it would be an unusual farmer who would buy expensive machinery for each individual in a herd, or spend the time measuring the breath of every cow.聽

鈥淭he challenge comes in capturing the methane,鈥� says Joe Rudek, lead senior scientist at the Environmental Defense Fund. 鈥淐ows are breathing out this methane. You鈥檝e got them walking around in a pasture, how do you capture that methane that鈥檚 coming out of the cows鈥� mouth and nostrils?鈥�

So instead of individually measuring each cow, scientists are trying to build up a robust sample size of measurements that would let them statistically predict聽methane emissions, both broadly and specifically. One contraption they use now is called the GreenFeed 鈥� basically a high-tech box with cow treats. When the cow puts her head into it to eat, the box measures methane and other gases. These instruments are portable, so theoretically farmers can use them in different locations.

But, Dr. McFadden says, those measurements are not always exact. That鈥檚 why his respiration chambers are important. Because the pods are highly accurate, closed systems, they can calibrate other machines.

鈥淭hese are the gold standard,鈥� he says. And it鈥檚 not just for methane, he adds. The chambers can help him monitor other inputs and outputs that can give clues about animal health and well-being, and about how the animal uses energy 鈥� as well as about other greenhouse gases, such as nitrous oxide.

Wider applications聽

And there is a lot of attention to what those chambers are showing.

Although only a few research centers in the U.S. focus on methane and livestock, many for-profit businesses are keenly interested in their findings. A substantial marketplace exists for methane solutions: Food companies are scrambling to meet emission pledges throughout their supply chains, while governments work to meet their own climate goals.

Dr. McFadden gets regular calls from startup companies asking him to test their products, but he can only do so much with the time and resources he has, he says.聽聽

It鈥檚 not straightforward to test a feed additive, for instance. Not only does the additive have to lower methane, it must not hurt the cow or pose any risk to food safety. And it should also have some benefit to cash-strapped farmers, who are loath to spend money on new products that do nothing for their bottom lines.聽聽

Across the country, at the University of California, Davis, professor Ermias Kebreab is also working with dairy cows, and has his eye on some solutions. In addition to feed additives, he is measuring what happens when cows eat local agricultural by-products, such as the grape residue from winemaking. GreenFeed measurements are finding some promising initial results, he says.聽聽聽

鈥淲e found a 10% to 12% reduction in emissions,鈥� he says. 鈥淎nimals were happy to eat it 鈥� and it avoids the emissions from putting it into a landfill.鈥澛犅�

Not only that, he says, but grape pomace 鈥� the fruit鈥檚 leftover skin, seeds, or stems 鈥� seems to improve milk quality.聽

鈥淚t鈥檚 a win-win kind of situation,鈥� he says.聽