Hey Chad,
You have already gotten some very good ideas. Some of this is the same...
My feedlot cattle only get hay every other day. I give them one flake, block, chunk or whatever you would call it in Ga. Once every couple of weeks I use straw instead of hay. So, like the others said, cut down the hay. You are filling him but what you want him to do is eat more grain.
You can get corn oil from the feed mill. Put 1/4 cup on each feeding.
Years ago I used what was called Baby Beef that was a 25% pellet. Now I think Purina makes a 35% pellet. Don't know for sure what they call it. I used to only use it on weaned calves, but that would sure give him a boost.
Be careful about adding too much too quick or changing things too fast. The last thing you want to do is founder him or throw him off feed.
I am a true believer in giving Probios whenever the mood trikes me or a calf looks at me cross-eyed. It wouldn't hurt to give him a few doses.
Good luck. Let us know how it all comes out.
Malinda