rider4life - you would be correct if she was feeding a complete feed or high amounts of feed. However, she is feeding a ration balancer. They are all at about 30% protien, but you feed them at 1-2lbs per day so the horse is only getting .3-.6 lbs of protien. Compared to a 14% feed fed at 15 pounds a day 2.1 pounds protien.
Barnprincess - It isn't a "supplement" per se. Although it is designed to meet vitamin/mineral requirements. Look at it this way. A ration balancer like your feeding is like a complete feed for vitamins/minerals. It isn't going to provide protein, fat, calories, fiber or anything other than vitamin/minerals in appreciable amounts. It's designed to be the only "feed" (or supplement if you prefer to use that language) fed to a horse that needs vitamin/mineral requirements met, but that doesn't need extra protien, fat, calories, or fiber.
Does that all make sense?