I think if you are feeding a complete ration from one of the good feed companies, that you are probably 1/2 way there as far as feeding is concerned. You can add to it to help the cattle. For instance, if you need more body and guts, you can add some beet pulp. You can also feed one of the topdresses to help with hair and condition.
I think how you feed has more to do with it than what you feed. Good feeders do some things that I think are extremely important. I always tell my students that the key to a good feeding program is consistency. Feed at the same times every day--7:00 am and 5-6:00pm. Feed a consistant amount every feeding. Do the same thing every day. Cattle are creatures of habit and changing the routine can cause problems.
I think roughage is very important. We run the cattle free choice to round bales of average quality grass hay daily. We feed about 2-21/4% if their body weight of a high quality ration daily. Keep water troughs clean and full.
When you go to shows, feed in your road feed pans at home for a few days. Water in your water buckets for a few days prior to the show. Don't change your routine at the show! Feed and water at the same time you usually do. Tie out about the same time you turn out at home.
Hope this helps. We have been doing it for a long time and these are just some things that anyone can do and it really makes a difference in the way they eat and fill up when you get away from home.