Some Vermont dairy farmers are changing their cows' diet to help fight global warming.

Stonyfield Farm's Greener Cow Project aims to reduce the amount of gas cows burp by feeding them alfalfa, flax and grasses instead of corn or soy.

Project head Nancy Hirschberg says the feed is high in Omega 3 fatty acids and rebalances the cows' rumen, their first stomach.

One farm participating in the project says the diet change has reduced its cows' belches and also its vet bills. Coventry Valley Farm says its cows have fewer stomach ailments and foot problems, as well as shinier coats.

Research has found that the dairy industry contributes about 2 percent to the country's total greenhouse gas production. Most of it comes from the gas cows belch. The rest comes from growing feed crops for the cattle and processing and transporting the milk.