how now, brown cow?

As reported on Discovery Channel:

Farm animals like sheep and cows produce large amounts of methane gas when they digest their food. The gas then escapes out either end of the animal and into the atmosphere. This process accounts for one fifth of all the world's methane emissions, and since methane is a potent greenhouse gas, making cows and sheep less flatulent is a big priority in the fight against global warming. That's why a team of scientists in Western Australia has developed a vaccine that kills the methane-producing bacteria that live in the sheep's digestive tract. After two injections, the test sheep produced eight per cent less methane than before, and the scientists expect this percentage to increase as they refine the vaccine and make it more effective.

Hmmm. Maybe we should just eat more grain and less meat.