I had the same exact problem with an angus heifer last year, I would feed her twenty pounds a day, and I was doing everything I could imagine to make her fill out. When it came to show days, we would feed her a third of winner's fill and give her water thirty minutes before show. But after she hit about a year old, she started filling out, and now she looks wonderful, and you would've never imagined she was the same calf! I definitely like what others were saying, and suggesting, I wish I would've though about this website last year!