All three of my Thoroughbreds are skinny. The 15 year old gelding is reallyy skinny, his ribs stick out rather noticeably and he's just plain thin..but he was a rescue and I've always had a really hard time keeping weight on him. He's also built a lot slimmer and lighter boned than the other ones too. The three year old is not in such bad shape, but she's a bit bony also. I know this is partially because she hasn't filled out completely yet, but I'd still like to get some weight on her. The last Thoroughbred is a 9 year old mare, who is the fattest...she has a bit of a hay belly, but her ribs are slightly visible.
Their teeth are all in good shape, and they've been dewormed. What should I start giving them? Weight gain supplements seem really expensive. I don't want to give them lots of sweet feed because they'll get hot. Any suggestions on what and how much to feed them to help them gain weight that's not too expensive?