All I know is that some chickens do better on the game feed. It is higher in protein. I know someone who feeds gamefeed to her sebrights all the time and they thrive on it. She says they need that extra lil boost. Also for all the baby chicks she starts on game chick feed for the first three weeks to give them a really good healthy start.
I use game bird feed (Growth and Plumage for the young ones and Flyer for the older fowl). I have never had a problem, but we do mix it depending on who it is for. Corn and a laying pellet are mixed in for the older ones. This is used because it is one of the few feeds that are not medicated. So far there has not been a problem and all the little ones thrive on it.
Turkey starter is around the same in protein as game bird starter. I start all my Buckeyes on the turkey starter. Purina's turkey starter is 26% protein and there game bird starter is 30% protein.
Very good egg laying breeds are at a higher rick of prolapse when given high protein feeds before laying.