Cattle won't totally ruin your hunting, but they will definitely hurt it. A few cattle in a pasture won't hurt if they dont over graze, but they need to be out when hunting season is underway if possible. As others have said, their curiosity will have them following you to your stand and hanging around your stand after that. Forget feeders and putting out salt and minerals for the deer. Food plots, forget that too. Cattle will also make a lot of noise which really effects the quality of the hunting. One place I used to hunt was in CRP and had a creek running through it. Then the landowner took it out of CRP and rented it to a guy who loads it with cattle. They have destroyed all the cover along the creek, and it isn't even worth hunting anymore.