some feed it all the time, we use a product called x-pando, its in a pelleted form. apex is a good one and honor show chow is coming out with one soon called depth charge i believe. we feed everyday just a little more at shows.
We try to keep the calves eating as much volume as they will. We adjust the feed/beet pulp ratio according to how much or little weight they need to put on. For the extra fill at shows, we start about a week out and start adding full tank to their feed.
we feed it as a holder to a steer that is a little bit bigger than we want . Beet pulp makes them feel full. mix it with your feed really good so the don't choke on it.