The only reason you would give them any grain would be to get them used to coming up to eat so you can check on them and to mix in your salt, minerals, selenium, and vitamins. Wouldn't have to be much in the feed some molasses to hold it together and something with bulk and not alot of feed value. Calving cows right now that are only getting good quality hay and calves are coming out good size but not too big so far.