Something that occurred to me recently about the "problem" of methane created by cattle --

...the USDA Census of Agriculture for July 23, 2004 estimated that there were 103.6 million head of cattle in the US. In the 17th Century it is estimated that 60 million bison (Bison bison, a/k/a buffalo) roamed the US. Both are ruminants, i.e., cud chewers, and belong to the Bovidae family. If there's a methane problem from cattle, shouldn't there have been one from bison?

And yes, I recognize the difference in herd sizes.