Feeding fish oil to flatulent cows can help fight climate change, say scientists.

More than a third of all the world's methane emissions, around 900 billion tonnes every year, is generated by gut bacteria in farm animals such as cows, sheep and goats.

Farmyard animals release 900 billion tonnes of methane every year

By volume, methane is 20 times more powerful a greenhouse gas than carbon dioxide.

A new study suggests that including two per cent fish oil in the diet of cattle can significantly reduce the animals' methane emissions.

Presenting the findings today at the Society for General Microbiology's annual meeting in Harrogate, University College Dublin scientist Dr Lorraine Lillis said: 'The fish oil affects the methane-producing bacteria in the rumen part of the cow's gut, leading to reduced emissions.

'Understanding which microbial species are particularly influenced by changes in diet and relating them to methane production could bring about a more targeted approach to reducing methane emissions in animals.'

Fish oil contains omega-3 fatty acids which have been shown to help the heart and circulatory systems of livestock as well as improve meat quality.