We could breed climate-friendly cows that belch less methane

Cows could be selectively bred to cut their significant contribution to global warming in half, researchers have proposed.

Livestock are responsible for 14.5 per cent of global greenhouse gas emissions, with the majority stemming from beef and milk production, largely because flatulent, belching cattle emit so much methane. Researchers have previously looked at tweaking their diet to reduce these emissions, such as by adding seaweed.

But now there might be a long-term solution, as it appears that a core group of gut microbes play a key role in how much methane a cow produces. The bacteria are closely correlated to the cows’ genetic makeup, suggesting the drivers for emissions are passed down through generations.

“Because of the heritability, it should be possible using that information to breed animals for low emissions and increased productivity,” says John Wallace of the University of Aberdeen, UK, who led the research. The microbiome of herds could be sequenced and individual animals with high emissions selectively bred out. Eliminating the worst offenders in the microbiome could cut methane by 50 per cent, Wallace says.

But this breeding process would take decades, and we need to reduce emissions much faster. A potentially quicker approach could be to see if specific genes are responsible – Wallace and colleagues looked at genetic variations known as single nucleotide polymorphisms (SNPs), not genes – and knock them out if it could be done without harm.

A simpler, short-term idea is a probiotic for young cattle to alter their microbiome to cut emissions, says Wallace. “That sort of inoculation for young animals is not as difficult as you might think.”

James Osman of the UK National Farmers Union says: “Research to better understand the genetics of low-methane emitting ruminant livestock, and any trade-offs with other important traits, is absolutely key.”

The researchers looked at 1016 cows across seven farms in Europe over four years, finding that at least half of the animals at all the farms had the same group of 500 gut microbes. Genetic analysis found a small but abundant number of those were heritable and played a key role in determining methane emissions.

Journal reference: Science Advances, DOI: 10.1126/sciadv.aav8391