The British Society of Animal Science conference

Animal methane production on climate change agenda

METHANE production by ruminants and its contribution to climate change were now concerning politicians and Defra, claimed Prof Jamie Newbold from the Institute of Rural Sciences, University of Wales, Aberystwyth.

Starting this month, a £750,000 Defra-funded project will look at ways of reducing methane emissions by ruminants, which has a global warming potential 23 times that of carbon dioxide. It will be carried out over the next three years by the University of Wales, IGER and the University of Reading.

“On a global scale, 16 per cent of methane emissions come from ruminants,” said Prof Newbold. “In the UK, 25 per cent of methane emissions come from ruminants and in Wales the figure is 50 per cent.

“This is why Defra and politicians are getting interested in methane emissions. Various feed companies are also getting involved.”

The new project will look at reducing ruminant methane production with feed additives, such as essential oils or garlic or various management regimes, such as the concentrate to forage ratio in the diet or using high sugar grasses.

“Cows can produce 500 litres of methane a day and sheep 30 litres,” said Prof Newbold. “We will be aiming to cut these emissions by 25 per cent.”

There were three papers on methane emissions at the BSAS covering sheep, beef and dairy cows, including one by Prof Newbold. He explained how selective suppression of rumen protozoa in lambs could decrease methane emissions without adversely affecting feed intake or growth rates.

“A promising approach to reduce methane release is associated with suppressing protozoa because up to 25 per cent of the methanogens in the rumen are associated with them,” he said. “But contradictory results have been reported between in vivo and in vitro data and short- and long-term defaunation experiments.”

Prof Newbold’s study involved 10 lambs, taken from the ewe within 24 hours after birth, kept isolated from other adult animals and bottle fed for the first six weeks. Once weaned, five of them were given, orally, 10ml of rumen fluid collected from adult sheep and the other five lambs were given 10ml of protozoa-free rumen fluid.

Both groups were kept isolated and fed a mix of concentrate supplement and grass hay for three months until they reached 40kg. At this weight, they were introduced to chambers to measure methane emissions over a three-day period.

The ‘protozoa-free’ lambs remained defaunated during the trial, but no differences were observed in liveweight gain or daily dry matter intakes between the groups.

“Protozoa-free lambs had lower daily methane emissions and methane produced per kilogram of dry matter intake than faunated lambs. The reduction was 26 per cent less at just 26 litres per day compared with 35.2 litres per day,” said Prof Newbold.

Work by Michel Doreau and his team, from INRA in France, has shown that feeding beef cattle a diet high in concentrates to minimise energy losses in the form of methane is possible without impairing intake or digestibility.

They focused on measuring methane emissions from young bulls fed three contrasting finishing diets that were characteristic of three intensive French production systems.

Work at the Agri-Food and Biosciences Institute, Hillsborough, Northern Ireland investigated how different forage types affected methane production by dairy cows. Cows were fed 5kg of concentrates and ad-lib forage – either grass silage, maize silage or fermented wholecrop wheat.

The researchers concluded that cows fed grass silage produced significantly more methane than those fed maize silage or wholecrop wheat.