Bovine belching to blame for high methane output
Published 06/12/2010 | 05:00
WHAT weighs in at 490kg and produces 120kg of methane gas a year? A belching bovine.
Some may have thought it was flatulent-happy cows that were contributing to Ireland's greenhouse gas emissions problem.
In fact, it is the methane gas emitted from cows during burps and breathing as they chew the cud that accounts for the single largest source of greenhouse gas in the Irish agricultural sector.
Scientists at the farming body Teagasc's Moorepark research centre at Fermoy, Co Cork, equipped cows with devices resembling jet-packs on their backs as they probed methods of reducing the amount of potent burps emitted during milk production.
Matthew Deighton, a research scientist on the project, highlighted it as a significant challenge for agriculture -- particularly as milk production is expected to increase with the abolition of milk quotas in 2015.
"It is early days. We have some very interesting results which I think are going to support the efficiency of Irish pastoral milk production but the research is ongoing and it is a complex interaction between the cow and diet," Mr Deighton said.
"It is a little bit early for a solution in terms of providing a directive to farmers at this point."
Ireland is committed to reducing greenhouse gas emissions by 2020 to 20pc below levels recorded in 1990. The Department of Agriculture has already ruled out reducing the size of the nation's herd.
The majority of the methane released is formed as the cows digest their food and then is burped up with the cow silently exhaling the gas through its mouth and nostrils.
"The majority of the methane gas is expelled through the mouth and nostrils. It is a four-stomach fermentation of feed, which is then belched and exhaled," Mr Deighton explained. "Approximately 95pc is expelled in that route."
The research team compared the grass diet, methane emissions and milk production of around 50 cows.
The gas-collection devices were attached to the cows' backs with a pipe running to just above each cow's nostril to examine the concentration of methane in the exhaled gases released through belching and respiration.
"The cows really don't mind at all and get on with their normal routine," Mr Deighton said.
The research, funded by the Department of Agriculture, will also compare the emissions from three different breeds.
Earlier this year, the researchers compared the output produced by cows grazing outdoors on grass during milk production against cows kept indoors and fed on rations. It found the production of milk using cows fed indoors was less efficient in terms of emissions.