wild weird, your nutritional issue.
Another thing to look at is intestinal issues, something that would have made it more difficult for them to absorb nutrients... a heavy worm load would be the most common culprit.
The problem though is if they have been nutritional deficient during their growth then the nutritional issues could cause permanent narrow hips, or perpetual unthriftiness that they cannot recover from. It will definitely slow down their maturation.
Unfortunately, if the people that are hauling, storing, and then selling the feed bags are not careful to make sure that the bags are never baked, and do not get too old, many essential nutrients are lost.
I am not sure how to get around that problem, since there is no way to know what you are buying at the store, how old it is and how it has been treated (at least the feed that I buy has no date stamp). Luckily for me there is only one local feed available, so it flies off the shelves, I know it is never old, and living in a colder part of Alaska, it would be difficult indeed to bake nutrients out of anything.