A cow peers out the window of its hutch on a Wisconsin dairy farm.
A cow peers out the window of its hutch on a Wisconsin dairy farm. - 
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Doug Krizner: A cow is more damaging to the environment than an SUV. That's the claim of climate scientists in Britain. One cow emits more greenhouse gas in a single day than a large car. And as Stephen Beard reports, that's not just hot air.

Stephen Beard: Rearing livestock causes 20 percent of the world's greenhouse gases, from the clearing of land and the growing and harvesting of cattle feed.

But the bulk of the emissions come from the other end of the business.

Every day the cattle themselves emit up to 500 liters of methane, and that's 20 times more potent as a greenhouse gas than carbon dioxide.

In a $1.5 million study, Dr. David Chadwick and his colleagues at the Institute of Grassland Research are trying tackle to problem.

Dr. David Chadwick: What we're trying to do is produce grass and clover that is more digestible for the animals themselves. The amount of methane that's generated by the animals is really a consequence of the amount they eat and the quality of the forage that they're eating.

Early results show that extracts of garlic in fodder can cut methane emissions by 50 percent. Tests are underway to see whether the garlic gives the animals bad breath or taints their meat and milk.

In London, this is Stephen Beard for Marketplace.