Mine are on pasture and probably soon a round bale. I don't grain my bred heifers that much unless it is real cold. If you feed them too much it can cause the birth weights to get a little big. Of course you don't want them skin and bones either.
Well, I don't drylot any cattle. If I did I would probably feed them hay with a high quality silage. I show angus, and after the summer shows I usually take a month to two months and kick them out on pasture to freshen them up. I will start feeding them about a month before the show their regular show ration, or I might bump them up a bit.