I wouldn't dump whole corn to a TB... myself! LOL, they're hot enough as is!
Here's what I've been feeding Moose, my TB project. (I posted earlier in the riding/horse critique section: How's he looking now?)
40lbs of good mare/foal pellets
50lbs alfalfa pellets
50lbs of either 14% performance or 14% senior pellets
50lbs whole crimped oats
I have my TB on a 1 1/2 gallons (lg coffee cans) twice a day, and all the hay and grass he can eat. The hay I feed is high protein, either Teff/Teft grass, or Timothy/Alfalfa.
I supplement him with a weekly probiotic, daily with MSM, Glucosamine, GrowColt, Biotin, and Omegatin (omega 3 fatty acids).
The sugar in corn can cause anemia if fed to a malnourished horse, as an immunosuppresive. PM me if you'd like some more info!