We raise show and commercial cattle. Also kids show steers & heifers. Long time family tradition showing and raising cattle.
I'd find a reasonable priced cattle feed ration that's at least around 12% Protein, 14% Fiber & 5% Fat. You going to feed twice a day and gradually increase your total pounds of feed per day based on weight gains.
Then what I'd recommend is get you a big crock pot and cook some stream rolled corn and steam rolled barley every day to add to the grain ration. Have a coastal round bale in the pen to graze on all day or get some square bales of coastal hay & give 2 flakes with the grain twice a day.
If you don't mind spending around $12 a bag for good feed then you can feed a good show cattle feed. I use Lyssy & Eckel show feed. The two Finishers are the show calf #150 & #160.
The Coop makes some good show feeds one would be Horn show feed. That's sold in a lot of feed stores across the State. You can still add the cook corn and barley as well if you use a show feed finisher with Hay.