I want to start supplementing him because I know he obviously doesn't get all of his nutrition from just the hay. I especially want something that is good for the skin and coat, because his only problem seems to be rain rot. He and my mare get it a lot, and I am fighting it constantly. They have a nice shelter to get out of the weather, but they never use it. They just stand out in the rain and roll in mud.
Anyway, I'd like an all-in-one or suggestions on what the best combination would be. I've heard good things about Smart Pak, but also that they are very expensive. I have three horses to supplement, one who is recovering from hoof injury and infection, so he requires a lot of maintenance.
My mare is a four year old Appaloosa. She's also currently pasture fluff. Same basic idea as the gelding. She doesn't have any special requirements aside from skin and coat.