Wow- my TB gets only 1 qt oats, pasture and free choice grass hay. Granted he's not a warmblood, but I would be leary of that much grain and the effect on joints. I like ration balancers also when pasture is in but have to be careul and watch for fluid in the joints. Try some cool calories, or higher fat grain. Go for quality over quantity if you can. Yearlings go through ribby growth spurts and tend to look rough even when they are healthy.
I would definitely add fat, like rice bran, if he's already getting the recommended amount of feed. I would also make sure he's getting a high quality feed that is made for young, growing horses that is low in starches.
And where you are, is Dr Green out yet?
I am not a big supporter of the line class look for growing youngsters.
Ribs are not evil.
Think of it as growing teenagers kids, they get lanky too, you wouldnt make them gain roundness would you?
Just read- this horse is a July baby? He will have to show against early year babies- he wont ever look as mature.
Mine is still yak and ribby (wormed and just put on rice bran pellets) but I would prefer it that way. He was an April foal who lost mom at 7 weeks...doing great, has HUGE joints (WBx) and can't wait to see him shed out whenever the weather decides what it's going to finally do.....
Foals should be wormed monthly from about 1 month to 1 year. If he's been on a 6 week rotation, he may indeed be wormy.
I would add fat as others have suggested. Not a lot more protein. But I wouldn't really to fatten him up. More shine him up. Besides, he may look completely different in a month or two on his own.
My vet just told me not to deworm my foal until it is at least 4 months old, and then not to over-do it, because they are seeing a lot of resistance to most wormers on the market. Maybe do a fecal and see?
I keep telling myself if you can't say anything nice, don't say anything at all but that is easier said than done on a discussion board. I would get the vet involved because that horse needs a lot of help.