10 July 2007

3 minute read

Europe

Birdsfoot trefoil has a distinctive three-toed yellow flower

The Birdsfoot trefoil is being studied by scientists at the Institute of Grassland and Environmental Research in Aberystwyth as a way of making cows digest more efficiently - which means they make more milk and emit less gas.

The £770,000 study was commissioned this year by the Department for the Environment, Food and Rural Affairs after ministers became concerned about the amount of methane emitted by livestock agriculture - thought to amount to about a quarter of all methane emissions caused by man.

Methane, which is 23 times more powerful than carbon dioxide as a greenhouse gas, is emitted at the prodigious rate of 100 to 200 litres a day by the average dairy cow, mainly from the front end, according to Michael Abberton of the Institute.

Agirculture accounts for seven per cent of all Britain's methane gas emissions.

Dr Abberton said the Institute was looking at using Birdsfoot trefoil, Lotus corniculatus, in a planted mix of white clover and perennial ryegrass to improve the efficiency with which food was absorbed by the cow's stomach.

Normally, the efficiency of cow's stomachs is very low at around 20 per cent - with the undigested grass coming out as either waste or methane.

Using a mixture which includes Birdsfoot trefoil enables the efficiency of the cow's stomach at processing the nitrogen content of grass to be increased to around 34 per cent, he said.

This can have benefits for the farmer in milk production and produce less methane gas and less nitrate pollution in agricultural run-off.

Studies in New Zealand have shown that changing the composition of cows' food can achieve savings in methane of up to 50 per cent.

Birdsfoot trefoil, with its distinctive three-toed yellow flower, contains tannins which appear to moderate the activities of microbes in the cow's gut, enabling the cow to digest the latest generation of high-sugar grasses more efficiently without also breaking down proteins which cause the production of methane.

The tannins also make it less likely that the cow will get bloat - an affliction of livestock that eat a diet too rich in protein.

Dr Abberton said: "Birdsfoot trefoil is not widely grown at all. We are trying to grow one that grows and competes better in UK conditions."

A briefing at London's Science Media Centre also heard that good soil management can lock up carbon from the atmosphere but poor management, such as allowing peat bogs to dry out, can release it.

David Poulson, a senior fellow at Rothamsted Research, said that with more crop rotations, more use of municipal compost in agriculture and the minimum amount of tillage, Europe could avoid one per cent a year of its emissions of carbon dioxide.

Jeremy Dyson of Syngenta Crop Protection said that the company had conducted a three-year study of low tillage agriculture - planting crops without cultivating the land first - and found that it could stop the loss of organic carbon from the soil but not as much as some studies in the United States had suggested.

Source: The Telegraph.co.uk