That must be the problem. I checked with the local feed store and Tractor Supply and all they had was the regular chick feed, 16-18% I think. The only feed higher than that is a small 5lbs bag of game bird/showbird 24% feed that I use to start my turkey, peafowl, quail, and guinea babies on. And it's like $9 per 5lb bag, so it's not very realistic to raise broilers on.
You need protein in a meat bird to start with or be free ranging so they can eat bugs. They only need it for a couple weeks but without it they are hurting units. They cannot get proper bone and organ development on 16%.