Oh wait, I just looked up the coccostuff:
Coccidiosis. A parasitic protozoal infestation, usually occurring in damp, unclean housing conditions.
So if the main purpose of the medicated feed is to prevent this then I am hoping my chicks will not need it because a) I want to keep their housing clean and b) even when they're out and about there will be 5 chickens on 5 acres in dry and sandy Texas so not much chance of damp and muddy, etc.
What else is it medicated for?