The cattle are angus and angus cross. When a 2,000 lb bull or the large cows want something a normal deer pen isn't going to hold them out once they get a whiff of that molasses.
And yeah putting a $10 block on the ground unprotected would be pointless. It would be gone in less than 24 hrs either by the cows or hogs rolling it off. I put a 125 lb protein tub out to supplement my free range 19 head of sheep and it only lasted 6 days.