What To Feed Horse?

my horse was in hopsitalized for about 6 months last year, and while he was there, we found a great grain. its pretty cheap, from what i hear from my dad, and its called nutrena safe choice and is vet recommended. we have used it to help our horse after being home for a year [getting 200 pounds overweight] loose all the weight he had gained. and its worked pretty good. && to keep the weight on, you just feed as you need.