Air Date: Week of July 29, 2011

Methane is a potent greenhouse gas but estimating how much ruminating animals produce has not been easy. Now scientists have found a correlation between levels of a compound in manure and the amount of methane released by the animal. Living on Earth’s Anne-Marie Singh brings us this science note.

Transcript

[COWBELLS, MOOING]

SINGH: Cow belches and flatulence produce large quantities of methane, a greenhouse gas 21 times more toxic than carbon dioxide. Now researchers have found that analyzing cow poop can provide valuable information about the amount of methane that’s released into the atmosphere.

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SINGH: Cows, sheep, and other ruminant animals with four-chambered stomachs contain billions of microbes which help them digest grass and hay. Some of these microbes produce a compound called archaeol, which is found in feces.

While it’s been relatively easy to calculate CO2 emissions caused by human activity, it’s much harder to estimate the amount of methane emitted from livestock. Researchers from the UK and Ireland believed there is a correlation between the levels of archaeol in poop and methane released by the animal. To prove this, they devised an experiment.

They collected poop samples from twelve steers to test how much archaeol was present. Some of the male cattle had diets consisting of fermented grass, called silage. The others consumed a tasty mix of silage and dry food. The steers with the grass diet had higher levels of archaeol in their poop than the cattle which ate the silage mixture. The more archaeol there was in the poop, the more methane, in the form of burps and flatulence, was released by the animals.

This study suggests that methane emissions can be regulated by controlling the diet of domestic livestock. And if further research confirms archaeol to be a reliable biomarker, then scientists could look to piles of poop for greener pastures. That’s this week’s Note on Emerging Science. I’m Anne-Marie Singh.

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Links

Press Release on the study on Pub Med

Read up about methane on the EPA website