I' ve hunted with cows and deer my whole life and while their not the best of buddies, the cows can help you out. If you see cows feeding in the woods, there' s probably persimmons or acorns on the ground in that area and that makes it good place to hunt when the cows aren' t around. Also, I' ve spotted more than one deer by watching the cows. When a cow see' s a deer, that cow will stare at it until it' s sure of what it is. If theres a bunch of cows and a couple of them are looking in a specific direction, I look where the cow is looking and sometimes it' s a deer, sometimes it' s a coyote, sometimes a person that ain' t suppose to be there. Horses are also great for spotting deer.
Bulls and some cows can mess your whole day up, too, kind of like Taz said, they can be bullies.