Hi,
I don't know much about them yet, as I just got my first one about 4 mos ago. I also have two mini horses. He was really skinny when he got here, so I started giving him 1/4 cup of 12% sweet feed 2x a day....he also eats grass hay with the horses. That must have been too much because now he has a big belly. I've cut him back to 1/8 cup each feeding. We'll see if that makes a difference. I have already found that they put on weight a lot easier than the horses do. Both of the horses are very easy keepers and get 1/2 cup 2x a day. I'm sure somebody who has more experience with them will be able to help you out.