AN Irish scientist has proposed replanting pastures with modified grass in an attempt to cut down on cattle flatulence, a major source of the country’s greenhouse-gas emissions.

The recommendation is made in a study commissioned by the Environmental Protection Agency (EPA), which this month will outline options for dealing with greenhouse gas emissions from the agricultural sector. Apart from replanting pastures with special grass that would reduce the amount of methane produced by cows, another proposal is to breed cattle that can be slaughtered at a younger age, thereby reducing the amount of time they are alive and releasing gas.

Bovine belching and farting causes 14% of the world’s emissions of methane, a gas which traps heat in the atmosphere 20 times more effectively than carbon dioxide (CO2) and takes up to 15 years to dissipate. Over the last 200 years, methane concentrations in the atmosphere have more than doubled.

The latest research was commissioned by the EPA following the 2000 National Climate Change Strategy and was carried out by Frank O’Mara of University College Dublin, with a grant of €645,000 as well as €1.5m from the Department of Agriculture.

At 29% of greenhouse gas emissions, agriculture accounts for more than any other sector of the economy, more than in any other EU country and almost double the proportion in France where farming accounts for just 17%.

More than half of agricultural sector emissions are produced by cattle digesting grass. The process, “enteric fermentation”, creates methane, which must be released at either end. Methane from both sheep and cattle accounts for the second largest single source of greenhouse gases in Ireland O’Mara, who will present the findings next week at an Agricultural Science Association conference on global climate change, says the most efficient way of changing the chemistry of cows’ digestion is to create new forms of grass.

“We looked first at feed and found that the nearest to market potential are oils, such as coconut oil. If you add those to the diet, they do reduce emissions, but they are expensive and the bottom line for a farmer is that it probably won’t improve his profitability,” he said.

“Researchers in Scotland discovered that organic acids have a huge impact. They do reduce emissions but they’re extremely expensive.

“We’re now trying to see if we can find or breed a new species of grass that has high levels of these organic acids. It would require replanting pastures, but a percentage of them are replanted each year so it wouldn’t require a hugely extensive reseeding programme.”

The EPA is to recommend further government funding for research into creating new types of grass with fumaric acid, which is essential to the respiration of animal and vegetable tissues and occurs in human skin during exposure to sunlight.

Another more immediate and practical recommendation in O’Mara’s report is to reduce the age at which cows are slaughtered. “The longer a cow takes to produce a quota, the greater the emissions,” he said. “Our dairy cow numbers have been reduced by 15-20% since 1990 leading to a significant reduction in emissions from the herd.

“The average yield per cow has increased by about 20%, we need fewer of them. In the beef sector, we can produce the animals more efficiently, and get them to grow more efficiently so we can slaughter them at a younger age. It’s called bull-beef production.

“If you rear the animals as bulls, you can slaughter them at about 12 months, but if you rear them as castrated animals, bullocks, they generally take 24 months before they’re fit to kill. An animal that’s slaughtered after 12 months will produce a lot fewer emissions.”

Gerard O’Leary, a programme manager at the EPA, said the agency will recommend that the government creates incentives for farmers to take up the proposals outlined in O’Mara’s report and build on the research to make Ireland a world leader in agricultural methane emissions reduction.

“This cutting-edge research could help us to achieve our Kyoto targets and to develop technologies and expertise that we could export,” O’Leary said. “Transport emissions are up 130% in 10 years, so we must start making inroads into agriculture,” said O’Leary.

“In this country we’re good at growing grass. So if we can get the right grass, that will help reduce the emissions from cattle, it should be easy to get everyone on board.”

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