Grain is a personal preference. Owning and Managing a boarding/training facility for 15 years and having several different breedings and competition styles, I have fed a pelleted feed and have had no problems (no colics), and no mice. Pelleted feed is highly digestible. Contact your nutritionalist from the brand you are feeding. Based on the hay, grass or pasture they will come up with the best program for you. I highly recommend the Kent/Blue Seal Brand. I personally don't like the mineral blocks, I use the loose minerals.