Enjoytheride, I could have written your post a few months ago. When I got my guy (OTTB) last fall, he’d been let down and was lean but very “soft”. Over the winter and spring as he worked more, he gained muscle but lost a bit of weight. I wasn’t worried, I wormed him regularly (he was wormy when I got him), upped his feed a bit and added corn oil…with no change, and I think he even lost some more weight. So this spring I had an energetic, shiny, better muscled but too ribby horse despite progressively increasing his calories over the prior several months.
I got serious and did three things: 1) Teeth floating (sedated, full mouth speculum, thorough exam). 2) Even though I’d been deworming him pretty aggressively (including Quest Plus), I gave him a Panacur PowerPak. 3) Added Amplify.
Didn’t take too long before it looked like it was working, and soon you could see the pounds piling on! Now he’s right where I want him. Which one of the things I did helped? I dunno. His teeth just had typical points, nothing exciting, BUT he started cleaning up his hay much better after floating. No idea if the PowerPak was necessary or not but I wanted to cover my bases. I’m mainly attributing the weight gain to Amplify - at first he wasn’t crazy about it, but ended up eating it just fine. Now that we’re at the “maintenance” stage, I think I’m going to wean off that and probably go to TC Senior. But I’m ready to add Amplify back in at the first sign of dropping weight - worked great for us.