Low methane-emitting cattle likely more productive

Low methane-emitting cattle likely more productive

Cattle vary by a factor of two or three in the amount of methane that their stomachs produce.

METHANE from cows — a greenhouse gas 25 times more powerful than carbon dioxide — makes up 20% of greenhouse emissions from agriculture, or about 1% of all anthropogenic greenhouse gases, according to Phil Garnsworthy, professor of dairy science at the University of Nottingham in the U.K.

Garnsworthy is also one of the project scientists of a European Union-funded research project called Ruminomics that is using cutting-edge science to reduce greenhouse gas emissions from cattle.

The key to the project is that cattle vary by a factor of two or three in the amount of methane their stomachs produce, Garnsworthy said. Therefore, it is possible to imagine a dairy herd producing the same volume of milk for lower greenhouse gas emissions. In addition, different diets mean that cows can produce the same amount of milk with lower emissions.

"It is possible to imagine cutting emissions from cattle by a fifth using a combination approach in which you would breed from lower-emitting cattle as well as changing their diets," Garnsworthy said.

Different genetic strains of cows emit different amounts of methane.

"There are three issues: diet, genetics and the microbiology of the cow's rumen. We think that animal genetics may well influence their gut microbiology. However, this link has not been proved, and we are still in the data collection phase," explained project scientist Lorenzo Morelli, a microbiologist and director of the faculty of agriculture at the Catholic University of Sacred Heart in Piacenza, Italy.

Until now, the European cattle industry was mainly interested in improving aspects of livestock such as their fertility and their overall shape. However, Morelli thinks that the market will soon add lower methane production to the list of desired cattle characteristics. Indeed, a herd that emits less methane is likely to be more productive.

"The methane is lost energy that could go into producing milk. So, if we can find the right genetic mix, we can find cattle that are less polluting, more productive and more profitable for the famer," Morelli added.

Independent experts agree that methane emissions could indeed be decreased, mainly through selection.

"The problem they are looking at is a (significant) one, but I believe that methane production (from this source) may be reduced by 10% in 10-15 years," suggested Yvette de Haas, a senior scientist with the animal sciences group at Wageningen University & Research Centre in the Netherlands. "Changed diets will affect methane production directly, but better genotypes alongside better diets will create a positive synergy (for lower emissions)."

Over the longer term, better genotypes will mean lower costs if special diets are not needed.

However, Garnsworthy warned that the project, which has two years to run, is not a simple one.

"Cows have a rumen as well a stomach," he said, and as a result, "their digestive system is far more complex and hard to understand than ours."

De Haas described the project's approach of gathering rumen samples and looking at the interaction with methane production as a novel one. Over time, it could improve practice with beef as well as dairy herds and with other ruminants such as sheep, deer and goats.

Other experts welcome the project too. What makes it new is its approach to linking genetics and microbiology, according to John McEwan, a senior scientist at AgResearch New Zealand. He thinks commercial applications of the project's findings could begin in three to five years if it is scaled up fast enough.

Volume:86 Issue:03

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