Here's a passage on the subject from The Third Revolution:
“What’s the difference? Don’t buffalo graze like cattle?”
“The bison are native to this land,” the chief said. “They’ve been here for tens of thousands of years. Cattle are from, I don’t know, Southeast Asia somewhere. Lowland animals. You have to encourage the grasses they like to eat, shelter them in the winter, kill all of the predators on the prairie, shoot the prairie dogs so they don’t step into their holes and break their legs. You have to fuss with the water access—cattle will hang out by their water source, they’ll crap in the same water they drink. They’re not very bright.”
He continued. “The bison, this is their land. They eat the native grasses. They’re fine on their own year round—even in the winter. They find their own food and water, and the rain and cold and snow don’t bother them. Prairie dogs don’t bother them; they don’t step in the holes. We don’t have to poison or shoot the wolves or the cougar or the coyote. They all live on their land together—the bison can handle the predators, and the predators know better than to attack a healthy bison herd. Especially when there are cattle around,” he laughed.
“The return of the bison lets us restore the balance to the land. They were here long before my people were, and a long, long time before your people were. All we really have to do is make sure they’re current on their brucellosis vaccinations, and only because the government makes us do it. Brucellosis doesn’t bother the bison. It only bothers cattle and cattle ranchers. And government inspectors.”
It's nice to see the world is catching up, however slowly... Read the entire article here: Farming Bison to Regenerate a North American Breed (Video)