The picture says it all from an article in the Telegraph: Scientists study cow farts and burps collected in a plastic tank to battle global warming.
Argentine scientists are strapping plastic tanks to the backs of cows
Experts said the slow digestive system of cows makes them a key producer of methane, a potent greenhouse gas that gets far less public attention than carbon dioxide.
Consider the other companion studies:
Methane, which is 23 times more powerful than carbon dioxide as a greenhouse gas, is emitted at the prodigious rate of 100 to 200 litres a day by the average dairy cow, mainly from the front end, according to Michael Abberton of the Institute.