We don't run as hard as we used to, but we feed out cattle for a living. Receiving cattle whether bought or weaned get ground hay, .75-1% body wt cracked corn, and Purina 36 O B 500 supplement. Once they get eating well we start introducing corn silage. Replacing the hay. 45-60 days in start uping the corn. Once I get them going I like to up them 1/2lb A week. Some where around 1,000lbs we switch to a 4020 RUM supplement. Those cattle all finish 18-22 mos old.
Used to manage a feed lot that I used the same work up program for, but once I got them to 22lbs of shell corn/day they went to a self feeder. Shell Corn and 4020 RUM, with corn stalks for roughage.
After a generation change I now consult for that feed lot. They have gone away from silage. The receiving cattle come off the trailer and straight on a self feeder. They use Purina Acuration now. Took 60-90days off there finish time. It's a trade off, there finish wts are not as heavy as they used to be.
All these cattle are fed either on concrete or slats.