Scientists discover low-methane sheep

It's hoped that low-methane sheep also give good wool and meat. Photo / Greg Bowker

Scientists have proven not all sheep are created equal, at least when it comes to belching greenhouse gases.

Researchers working for a Government partnership with the farming industry have discovered that some sheep naturally make less methane digesting their food than others - potentially opening the way for a low-methane breeding programme.

When fed grass, the difference in emissions between a low-methane flock and a high-methane flock was about 20 per cent.

The difference varied depending on what the sheep ate - but it was always there. "For the first time we have opened up the possibility we could breed animals with lower greenhouse gas emissions," said Harry Clark, the scientist heading the study at Agresearch.

"We definitely lead the world in this."

Scientists created two flocks by taking sheep from a larger flock, one at a time, and putting them in a sealed breathing chamber.

The sheep were fed a variety of foods while scientists measured the methane they made. Seemingly no matter what they ate, some sheep seemed genetically programmed to belch less gas.

The consistently low-emitting sheep were added to one flock, while consistently high-emitting sheep were added to the other.

The low-methane flock made 8 per cent less methane than the other flock when they were fed silage and other dry food.

The work was paid for by the Pastoral Greenhouse Gas Research Consortium - an alliance between the Government, scientists and the agriculture industry.

The consortium has about eight sheep in each flock so far, and manager Mark Aspin said the tests would be repeated to find more sheep for each flock. Although it is early days yet, scientists hope to ultimately breed from low-methane animals to cut the gas released by sheep, cows, goats and deer - which account for about one third of New Zealand's greenhouse gas emissions under internationally agreed limits.

Mr Aspin said the goal was to create a breeding programme to cut methane without compromising production.

Cows and sheep are genetically similar so the sheep tests will help understanding of cows.

Mr Aspin said more tests were needed to check that low-methane sheep were not genetic duds when it came to making milk, wool and meat - and that they passed their emissions profile to their offspring.

"The ideal situation is that we find high milk production or high meat production, high fertility and low methane in the same animal," he said.

Methane is a waste product of the unique way cows, sheep and other so-called ruminants digest their food, so it is possible animals that use less energy making that waste will be more efficient producers.

Mr Aspin said that, if a breeding programme was going to work, scientists would need to find a cheaper and quicker way of testing for methane production than putting each sheep in a breathing chamber.

That would be part of the further research. "We may find a saliva or blood profile in the lower-emitting animals that is easier to test," said Mr Aspin.

The consortium has a goal of cutting greenhouse gases per unit of milk, meat or wool by 10 per cent of 2004 levels by 2013.

Funders include Fonterra, Meat & Wool New Zealand, AgResearch and the Government's Foundation for Research Science and Technology.

WHAT'S THE GAS

Pastoral Greenhouse Gas Research Consortium
* Research funding body paid for by the Government's Foundation for Research Science and Technology with Fonterra, Meat & Wool New Zealand, DairyNZ, PGG Wrightson, Fert Research, Deer Research and AgResearch.

Goals
* Decrease agricultural greenhouse gases by 10 per cent per unit of production in 2013, compared with 2004.
* By 2013 have 33 per cent of farmers using at least one greenhouse gas mitigation technology.