[Mr. Lucky]

Cattle are ruminants and, as such, produce methane in their digestive process. The methane is expelled as a burp, not a fart. While this simple fact may not be known to the New York Times, it's hardly a secret. Google on something to the effect of "cow burps".

[TigersEye]

I'll take your (and Old Professor's) word for it.

To get back to the point of it; is there more domestic livestock than there used to be herds of wild ruminants? Do wild ruminants belch less?