Last night while grooming my horse he pooped and I noticed the pile was kind of small. I picked up one of the round balls of poop and it was a little hard. What can I feed him that will help him break down his food? He has plenty of access to clean water but he was in all day yesterday and I think the quality of the hay he is getting right now isn't very good. Otherwise he is normal. I'm afraid he's headed for an impaction colic.