Check out this interesting idea to save energy fostered by an individual in Sweden. He will pump 7,900 gallons of the fresh warm milk from the cows into some rooms in a historic castle. The warm milk will heat the rooms.
So, maybe cows should be declared "carbon neutral"? That is, the energy saved from using warm milk to heat rather than fossil fuels would balance out the CO2 production from all of their flatus and belching? (see my previous post on this topic http://cocanuts.blogspot.com/2008/01/global-warming-dogs-cows-and-beckham.html).