Animal burps and climate change are directly related, although that may seem a bit of a stretch for newcomers to the idea that farming contributes significantly to greenhouse gases.
New Zealand is home to 10 million cows and 26 million sheep. Together they produce over half of the country’s methane emissions. To reach its climate goals, the country must curb those emissions using science to define policy and government action to implement that policy.
The young bull’s head disappears into a green plastic hood. He scoops up a mouthful of dried pellets, chews, flicks his ears, and exhales. The hood is attached to a contraption on wheels that looks like a high-tech mobile pizza oven. However, the only thing cooking is a precise measurement of methane, a gas that has a global warming impact 84 times higher than that of carbon dioxide (CO2) over a 20-year period. The bull’s breath, laced with methane gas from his digestive tract, is hoovered up by a fan at a rate of 40 litres (8.8 gallons) per second, and measured in this device known as GreenFeed system.
Since 2021, Livestock Improvement Corporation (LIC) in New Zealand, and another cattle breeding cooperative, CRV Ambreed, have joined forces to measure the methane output of 800 young bulls. It’s the first step in breeding farm animals that naturally produce less methane; apparently, different animals produce different levels of methane and the scientists think they can breed from those producing less.
New Zealand is one of more than 100 countries signed up to the Global Methane Pledge. But while other nations focus on plugging leaks from oil fields and natural gas pipelines, New Zealand’s focus is on the methane brewed by microbes in the digestive tracts of farm animals, and belched into the atmosphere.
New Zealand is harnessing a range of scientific tools, including methane-blocking vaccines, inhibitors, and selective breeding, to curb its farming emissions. Methane inhibitors may be one of the technologies and one is already on the market internationally; a Dutch-developed feed additive called Bovaer. The compound can reduce dairy cow methane emissions by 30%. Another attractive tech solution is a methane-blocking vaccine, but that will take time to develop.
Selective breeding is another method that could produce good results. However, current research on low-methane dairy cattle rests on a foundation of research on sheep. While sheep emit, on average, 13kg of methane every year, compared to 98kg for a dairy cow, starting with sheep was a logistical choice. “Sheep are much easier to handle,” says Suzanne Rowe, senior scientist at AgResearch, “and their gestation period is much shorter.” Fourteen years ago, Rowe and a team of AgResearch scientists wondered whether a sheep’s methane emission levels was a trait that could be passed from one generation to the next. They gathered 1,000 sheep from across New Zealand and began to measure their gas outputs over 48 hours using a respiration chamber.
“It took years to get through the 1,000 animals,” says Rowe, explaining the painstaking process to refine measurement down to just one hour instead of 48. The “huge challenge” yielded three incredibly useful things: a flock of low-emitting sheep, a flock of high-emitting sheep, and a portable unit for fast methane measurement.
The two flocks were relocated to the same farm on New Zealand’s South Island. High emitters bred with other high emitters, and lows with lows. Every year, Rowe and her team measured the methane outputs of the new lambs. And every year, the low emitters got lower by about 1%. Today the difference between the high and low flocks is, on average, 18%. Plus, the reduction doesn’t appear to come at the cost of other desirable traits. In fact, changes that have emerged so far are positive. “Low-emitter sheep had more wool,” says Rowe. “We also found that they have a slightly different fatty acid profile in their milk, and their meat was leaner.”
What impact will selective breeding have on New Zealand’s methane emissions? For sheep, Rowe estimates a decrease in methane emissions of around 0.5 to 1% per year. “Over time, that quickly becomes substantial,” she says. “The other benefit is that, other than the actual measurement of the animal, it’s low cost, and it’s permanent.” But the impact of selective breeding is also slow to emerge, as genes filter through a population over time rather than acting instantaneously.
In Canada, low-methane bull semen became commercially available earlier this year. Semex, the company behind the genetics, says adoption of the low-methane trait could reduce Canada’s dairy herd emissions 20–30% by 2050.
Behind the incremental march of scientific efforts, the specter of a price on agricultural emissions looms large. New Zealand’s first attempt at introducing an agricultural emissions price levy, dates back to 2003, when a ‘fart tax’ furore erupted. ‘Fart tax’ is a misnomer, says Leahy, as most gases are expelled out the front end: “about 75:25 nostrils to mouth”.
The proposed levy would have raised NZ$8.4m (£3.1m or US$4.9m) per year for research. Vehement opposition from farmers saw one MP drive a tractor up the steps of parliament, and another lead two cows around parliament grounds, with one depositing a steaming cowpat in front of the parliament building.
Since then, the agriculture sector has lobbied hard to avoid being roped into New Zealand’s “Fart Tax” scheme, making it an outlier industry that doesn’t pay a price for its climate pollution.
Reducing methane in line with the official targets will be “challenging”. A few years ago it was thought unlikely that it would be possible to reduce the methane brewed in an animal’s gut. Today, there is selective sheep breeding, there are inhibitors, and there are some modified feeds. Hopefully science can outrun the agricultural lobby that will undoubtedly oppose many of these essential climate-change methods and policies.
Whatever happens, the relationship between animal burps and climate change will certainly be a major contributor to the solution of this major issue for the planet.
