I use Hygain Tru Care or Honey Bee - very good deeds and don't seem to make my TB hot
Omolene 300 is AMAZING for weight gain!
I love Millrun, it always works super well on every horse i know that's been on it. Truely the only way my horse isn't a twig
I use copra it is a coconut based feed (I’m pretty sure) and you soak it in your other hard feed for a minute and it expands, after a few feeds your horse should start to put on some weight. I hoped that helped :)
Id always suggest broodmare mix its designed to to support mares who not only have to feed themselves but their foals too so is great for putting on wieght and wont make him hot,also "fiberpro' is a really good fiber which will help out with gut health and prevent ulcers ect and another favorite of mine for tbs is 'copra' its a feed that requires soaking so will have to kepp in a cool dry place but its non sugary and super fatting tooo