Ruminant animals, like cows, produce a lot of methane—almost a quarter of U.S. emissions annually. And methane’s a nasty greenhouse gas. By some estimates, it has 25 times the potency of carbon dioxide.
Cows produce methane mostly when they belch (though also from farting). The gas is a byproduct of fibrous material the animals digest through their multi-chambered guts. The emissions, in fact, are not only bad for the atmosphere. They are also a sign of inefficiency: the cows are wasting energy, rather than making use of it.
John Wallace, a professor at the University of Aberdeen, in Scotland, is leading a big European Union-funded project, called Ruminomics, to look at new breeding methods that might lead to less methane output.
Scientists already know that certain diets lead cows to produce less methane. For example, in France one company is feeding its herds a mixture of alfalfa, linseed and grass, instead of a more standard corn and soy-based mix. As a result, it says the cows produce 20% less gas than normal. Similarly, in the U.S. many farmers use an antibiotic called Monensin which reduces methane by an estimated 15% (despite being banned in Europe for other reasons).
What interests Wallace, however, is that some animals seem to produce less (or more) methane under all conditions—in other words, irrespective of breed, and irrespective of what they are fed. There seems to be a genetic basis for gas releases, rather than just an environmental one.
"We have little evidence that breed makes any difference to methane emitted per kilogram of feed intake. It’s the inter-animal variation that is crucial for future breeding programs," he says, via email.
It’s still early days for the research. Wallace’s team has looked at the genetics of only 25 of 1,400 cows so far, and the project has another two and a half years to run. But, by the end of 2015, he should have finished developing saliva and milk tests that allow farmers to select animals that produce less methane.
If so, the work could be useful in curbing the problem of ruminant pollution.