[1] https://en.wikipedia.org/wiki/American_bison#Range_and_popul...
[2] http://www.cattlenetwork.com/advice-and-tips/cowcalf-produce...
[1] http://beef2live.com/story-world-cattle-inventory-ranking-co...
Here are three sources that say an order of magnitude means ten times as much:
https://en.wikipedia.org/wiki/Order_of_magnitude
Assume we could feed all the meat-eaters on a revolving 60M cattle--would we then have solved the problem? Or are we supposed to maintain a smaller-than-original population?
There is no single answer about what we're "supposed to" do, but it is clear that cattle are driving the increase of methane production and that methane is a far, far more potent greenhouse gas than C02. A plant-based replacement wins hands-down in any ecological analysis.