We know that the release of methane from ruminants is extremely damaging to the environment.

Dr Wallace of the Rowett Research Institute

Using aromatic extracts of herbs such as thyme, mint and others could reduce the level of fermentation in the rumen - causing less flatulence and a more bearable smell.

Dr John Wallace, head of the microbial metabolism research group at the Rowett, said: "We know that the release of methane from ruminants is extremely damaging to the environment.

"We believe our work has the potential to halt this increase and help stabilise the environment by taking a natural route to improved rumen fermentation.

"At the same time, we believe that the current growth in antibiotic resistance in humans, part of which is generally accepted to be linked to the use of antibiotics in animal feeding, could also be reduced by quite a substantial amount."

Dr Wallace said that the natural oils have a pleasant smell.

Significant improvement

He said: "Although the effects on the manure are small, the distinctive aroma is very obvious, indeed pleasant, in the building used to house the cattle."

The Rowett's interest in the potential feeding value of new plant species is rooted in 20 years of work with the International Livestock Research Institute (ILRI) in Addis Ababa, Ethiopia.

Scientists have found that foliage from a tree species in Africa appears to suppress the protozoa which inhabit the rumen.

Dr Wallace said that this suppression leads to a "significant improvement" in production efficiency which resulted in less methane and more benefit to the environment.

The 'novel plants' research project, of which the Rowett is the co-ordinating body, involves academic and commercial partners in Switzerland, Ireland, Spain, Germany and the UK.

The work is funded by the EU at �1.2m (1.94m Euros), plus a contribution of �85,000 (137,640) Euros from the Swiss government.