No wonder you're confused. WHEW!
If he was mine I'd:
Get a FEC (fecal egg count) done to make sure his belly isn't from some kind of worm. And de-worm according to that, IF necessary.
Soak his hay cubes and just give him a little hay to chew on so he feels like he's doing something all the time, until you can get his teeth done.
You always want to feed forage first, so the largest amount of feed should be hay in one form or another. You need to figure out what he SHOULD weigh and then what he DOES weigh. So, for instance, he's a 15.2 QH and stocky and he SHOULD weigh 1200 lbs. but he really weighs 950 lbs. He needs to gain 250 lbs, so you start by feeding 2% of his DESIRED body weight of hay, so 24 lbs of hay(s). If he can't chew the bermuda without quidding and/or swallowing it mostly unchewed, then the vet was right it can cause impaction colic.
If he can't chew 24 lbs of hay, he can't use it to fill out, so for now, wet down 20 lbs of hay cubes or pellets and just give him 5 lbs of hay to play with. Once he's eating all that hay or hay cubes, if he still needs more, then I'd probably put him on a Senior feed. You can also soak that so he can use it better. You'll want to split it into 2 or 3 feedings, he can't hold much more than 5 or 6 lbs of cubes at one feeding.
I like to feed my horses Fastrack, it seems to help them all utilize their feed better, but it really makes a difference with the older ones.
I'd start with the basics and then start adding, but not ever subtracting the forage, if that makes sense? He may have dropped the weight really quickly but until he gets his teeth fixed especially, it's going to take him a lot longer to regain his weight. And you want him to go fairly slow, you don't want him to founder.
Last edited by Dreamcatcher Arabians; 07-13-2013 at 02:39 AM.
Reason: I can't spell tonight.