When I was a kid, many moons ago, we never heard of hip displasia. Now that's all we hear about with big dogs. Brainwashed into feeding these dogs high powered feed which causes them to grow too fast. Same thing with colts. Whatever you decided to feed, feed only half the recommended amount. Keep in mind the feed company wants to keep selling you their feed so make blanket recommendations because they can't monitor the animal's progress. Good quality hay that is dust free is still the best thing to feed your youngster. His growth may be a little slower but he'll be better off for it.