Proof is in the cow pat
15 Aug 2011 by Evoluted New Media
Cows, sheep and other ruminants are thought to be responsible for a fifth of global methane production, but measuring exactly how much they contribute can be difficult.
Cows, sheep and other ruminants are thought to be responsible for a fifth of global methane production, but measuring exactly how much they contribute can be difficult.
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Scientists find a link between methane production and a microbe in cow pats |
Methane production in animals is often measured using a respiration chamber, but researchers from the University of Bristol and the Teagasc Animal and Grassland Research Centre in Ireland, fed two groups of cows different diets and analysed their excrement.
They found a link between methane production and the levels of a compound called archaeol – a symbiotic microbe thought to descend from archaea – in the faeces. The microbe lives in the foregut of ruminants and produce methane as a by-product of their metabolism – which ruminants release as a burp or flatulence.
Researchers believe the compound could be developed into a biomarker to estimate methane production from domestic and wild animals, allowing scientists to make more accurate assessments of their contribution to global greenhouse gas emissions.
“When it comes to calculating carbon budgets there is currently a lot of uncertainty surrounding animal methane contributions, particularly from wild ruminants,” said Dr Fiona Gill, who conducted the work as a postdoctoral researcher at Bristol.
“We’re quite good at measuring man-made CO2 emissions, but techniques to measure the animal production of methane ¬– a much more potent greenhouse gas – have serious limitations.”
Dr Gill says if we can identify a simple biomarker for methane production in animal stools, then this can be combined with information on diet and animal population numbers to estimate the animals’ total contribution to global methane levels.
Researchers also found the cows allowed to eat as much silage as they wanted emitted significantly more methane and had higher concentrations of archaeol in their faeces than those fed a fixed amount of silage, supplemented by concentrate feed.
“This confirms that manipulating the diet of domestic livestock could also be an important way of controlling methane gas emissions,” said principal investigator Dr Ian Bull.
