I know amounts to feed can vary from horse to horse, but here's what my guys are on...
Yearling 31" (mature 32/33) yearling stallion - 1.25# Progressive Nutrition grass balancer, 1/2 cup BOSS and free choice grass hay (he was on 1.5# of Nutrena Youth plus free choice grass hay until about a month ago - he just couldn't eat it fast enough to keep it fresh, so I put everybody on the same thing). He was also getting 1/2 pound of COB until a few days ago when I ran out, he doesn't seem to be missing it any.
2 year old 35" filly - 1/2# PN grass pellets, 1/4 cup BOSS and about 5# grass hay per day. She came to me pretty fat, having been on highly alfalfa based diet (almost pure alfalfa), she could hardly move she was so chubby. She's lost some weight and is now quite spunky.