Whats a good diet 4 a Thoroughbred?

His diet right now sounds pretty good. You should try feeding him about a scoop of soaked beet pulp too. Beet Pulp is like a God-send for OTTB. If you are having a really hard time keeping weight on, try a weight building supplement like Weight Builder. Unless he doesn't sweat even after a really hard work-out, then you don't need to feed him electrolytes. They are for horses that are worked very hard or have problems sweating.