I wouldn’t consider a horse on a grain free diet a hard keeper. I agree with the info everyone has been saying. Personaly I’ve had great luck with Poulin Grains. I feed the decade eventer 10-10 mixed with their beet pulp with soy, and rice bran. You want a high fat, high protein low starch diet. Not every barn wants to deal with beet pulp but in addition to the the feed qualities of it I like to feed a wetter meal to my boys. This diet workes well with the three horses in my barn, especially my elder boarder whom was woefully underweight when first coming to my barn. I do know Poulin grains will consult with you on a diet for your horse. I would have to think this is a service many of the grain suppliers like blue seal will offer. Good luck.