Sorry, that was a point from Guns, Germs and Steel by Jared Diamond. I should have just listed the cow, horse, sheep, goat, and pig.

Those are the basic examples of the few animals which are docile herbivores, breeding in captivity, growing to a large, breeding adult in a couple years, and which live in social groups that accept humans at the top of the hierarchy. Building a society with protein and labor from cows is much easier than, say, harnessing turkeys. There are a billion cows on the planet, but if human society grinds to a halt and we stop artificially inseminating them and running the feed plots those species might not survive.

Thank you! This book is actually on my night stand right now, next in line.

The list is generally cows, pigs, goats, sheep and horses. But it's not a rigid list; sometimes goats and sheep get merged, and sometimes chickens get added.