Morning - 2 flakes hay
4 quarts grain (Blue Seal Performance LS (low starch) )
Fat supplement (tried about 8 different ones with no results)
5 lbs alfalfa hay cubes
2 pounds rice bran
3 lbs beet pulp
(I wet it all up and let is soak into a nice mushy mash. He gobbled it up like a piggy.)
Dinner - Same as morning.
With this food, my horse remained a typical ribby TB.
Over the winter I found a place that feeds free choice hay. I decided to give it a try, ditched everything except the grain and the SmartGain fat supplement that ended up being the one that actually seemed to work. Despite a VERY cold winter, he gained about 200 lbs.
We left that place in April and now he's at a barn with not free choice, but amply hay, and very lush grass that they have access to about 4 hours a day. They didn't feed Blue Seal, so we switched a Poulin equivalent, Equi-Pro Performax. So now his diet is:
2 lbs Poulin morning and night, SmartGain supplement, hay & grass. The grass was the real key for him. Within 2 weeks of being there, we started seeing more weight gain. He's almost to where I'm going to ask to cut back on his grain a little. I didn't think that would ever happen.
Without the availability of grass, maybe you can substitute soaked alfalfa hay cubes? I'm thinking that would be the closest equivalent to grass. I do agree with others that sweet feed can overstoke a TB's furnace and they end up burning off calories standing still. Hope that helps.