I keep two horses on a paddock paradise track. One is PPID, 1,100 lb., hard keeper, one is a 850 lb., not PPID/IR but easy keeper. They are out together all day with about 20 lb. of hay, which they clean up. At evening feeding, I shut the PPID hard keeper horse in his stall and give him another 10 to 15 lb of hay, leave the easy keeper out (he has access to his stall but isn't shut in) and only give him about 2 to 3 lb. This isn't enough to keep him eating, so he searches out and eats the little grass and weed sprouts on the track at night, keeping it relatively grass-free for the PPID horse. This keeps both in good weight. I feed each the minerals balanced to the hay, in proportion to their ideal hay amount, even though I can only assume that's what they are getting by their body condition.