In a cream-colored metal barn two hours north of Wellington, New Zealand, a black-and-white dairy cow stands in what looks like an oversize fish tank. Through the transparent Plexiglas walls, she can see three other cows in adjacent identical cubicles munching their food in companionable silence. Tubes sprout from the tops of the boxes, exchanging fresh air for the stale stuff inside. The cows, their owners say, could help slow climate change.
Livestock has directly caused about one-quarter of Earth’s warming in the industrial age, and scientists from the U.S. departments of agriculture and energy say bigger, more resource-heavy cattle are accelerating the problem. Contrary to popular belief, cows contribute to global warming mostly through their burps, not their flatulence. So about a dozen scientists here at AgResearch Grasslands, a government-owned facility, are trying to develop a vaccine to stop those burps. “This is not a standard vaccine,” says Peter Janssen, the anti-burp program’s principal research scientist. “It’s proving to be an elusive little genie to get out of the bottle.”
The effort isn’t entirely altruistic. Grasslands is dedicated to boosting New Zealand’s dominant agriculture and biotech industries, and the country’s biggest company, Fonterra Co-operative Group Ltd., a $14 billion dairy processor, has vowed to increase its milk exports without increasing carbon emissions. But 2017 is set to be the third-hottest year on record—the top two were 2016 and 2015—so the globe can use all the help it can get, business-minded or not. “It’s essential to reduce global livestock emissions in order to reduce climate change consistent with what countries signed up to under the Paris Agreement,” says Andy Reisinger, deputy director of the New Zealand Agricultural Greenhouse Gas Research Centre.
Janssen and his team are trying to purge cow stomachs of methanogens, the microbes that convert hydrogen into methane, a potent greenhouse gas. It’s an unexpectedly delicate and difficult task, because cows rely on a host of other bacteria, fungi, and protozoa in their guts to digest the grasses they eat. Researchers have tried feeding them oregano, tea extracts, probiotics, antibiotics, seaweed (too toxic), coconut oil (too expensive), chloroform (too carcinogenic), and even leftover grains from beer brewing (which made cows poop more nitrous oxide, another greenhouse gas).
So far no vaccine has progressed far enough to be given to the cows in the cubicles, where methane output can be measured. The vaccine must first be successfully tested in the lab and on sheep. Although the scientists have figured out how to produce the desired antibodies in the cows, the animals continue to merrily burp. Janssen’s team is looking for proteins they can use to concoct a stronger vaccine, one that will better prime the cows’ immune systems to attack methanogens. A single methanogen genome has 2,000 proteins, so they’ve narrowed their search to a handful of candidates, which they think could knock out the gassiest microbes.
The hunt for a vaccine costs about $1.4 million a year, about two-thirds of which comes from the New Zealand government. Industry supplies the rest. The money is part of a $7.5 million pool for curbing farming gases meant to address New Zealand’s status as the world’s highest per capita methane emitter. Janssen says it may take five years or longer to create the right vaccine, but it will do much more to reduce bovine emissions than a treatment that Dutch company DSM is developing for bucket-fed cows. That’s because the vaccine will work just as well for grazers. “There aren’t too many ruminants in the world where the animals never get to eat grass,” he says, noting that even cows fattened with feed in a controlled environment typically start out in pastures.
DSM used computers to create a methane-blocking molecule called 3-nitrooxypropanol, or 3-NOP, that appears to cut burped methane by about a third when sprinkled on a cow’s food. The company, whose annual research and development budget is $500 million, is waiting for approval from the U.S. Food and Drug Administration, which is likely to take at least two more years. “For developed countries, this is the most promising technology at this point,” says Alexander Hristov, a Penn State professor of dairy nutrition who’s tested 3-NOP for DSM. The New Zealanders are leading the vaccine hunt, he says, but they haven’t developed a proven product they can offer to farmers.
Janssen, a bespectacled man with the lanky limbs of a longtime mountain explorer, says his team is also working on substances similar to 3-NOP that could be given in pill form. A complicating factor: No one knows how low-methane a cow can go without hurting its health or productivity. Trials suggest cows that burp less seem to cope fine, but scientists want to make sure there are no unintended consequences, such as reduced milk quality or quantity. “We need to understand where that tipping point is,” Janssen says.
Humans are the final hurdle. Canadian scientists created low-polluting pigs almost a decade ago, but people wouldn’t buy the genetically modified pork. “Farmers will produce what the consumer demands,” says Tim McAllister, who’s conducting trials of 3-NOP and other methane-reduction techniques for the Canadian government at the Lethbridge Research and Development Centre in Alberta. Soaring global demand for meat makes climate concerns pressing. North of Wellington, the cows seem content in their tanks, turning to watch as Janssen strides between their boxes. For now, their burps are packed with methane, but they may not have to be.
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