A ruminant fed a high quality, easily digested diet burps less than the same animal fed a rougher, less digestible diet. (although overfeeding an animal at any stage of its life also causing excessive gas). A cow, or buffalo, out on the range eats a lot less digestible food than one more intensely managed. Yuppie tree huggers acts as if this were rocket science; it's not.
Okay I went googling. Never really thought about it before — I’d heard vaguely that cows were supposed to eat grass not corn. While that’s true, it’s not because of methane but for other reasons (cow health, antibiotic use, fat, etc). I guess they say the best thing for cows to eat to reduce.. emissions.. is alfalfa. Funny — that’s a legume — I would have expected beans to make cows fart more. Oh sweet mystery of life.