The Washington Post posted an article yesterday discussing grass-fed beef and how production methods affect the balance of greenhouse gases like methane. Since cows produce methane as part of the digestion process, and methane can increase global warming by absorbing infrared radiation being given off from the Earth, this is an important question. But it is complicated by the fact that grain-finished beef gain weight faster than grass-finished beef, well managed pastures sequester more carbon in the ground and the plants than poorly managed pastures, and many other factors. The calculations for which is better for food, for the animals themselves, and for the planet as a whole are a lot more complicated than just monitoring methane production. You can read the full article discussing the pluses and minuses here.
