In a couple places I hunt there are cows. The deer really don't seem to mind a whole lot. We have one big pasture that has quite a few cows in it and every year we see a pretty good amount of deer. Our cows really won't start mooing when they see someone, they will generally run away and then slowly come back in to where ever you are. My grandpa has a decent sized feed lot at his place that is always full of cows and the deer are always around and coming through the pastures, but, I am pretty sure the only reason for this is because of the corn, hay and silage that is fed to the cows is easy pickings for the deer.