I think that medicated only comes in chick starter, so there probably isn't anything called flock raiser/grower that is unmedicated....they are all unmedicated as far as I know. Anyway, Ridley has a feed called pullet grower that looks like it would be fine for that period of time. I feed a higher protein and theirs is only 16% (+/-). It should be good until they start laying and need oyster shell. I leave mine on the grower and put out a bowl of oyster shell for the layers to use if they need it, but some buy layer feed that already has calcium in it for the laying hens. Whatever works best for you is what you should do. I just wouldn't feed layer feed to any birds that are not laying.When I ask about unmedicated flock raiser/ grower they look at me like I made it up at the feed store. I am in Australia. What can I feed my whole flock from 6 weeks, 15 weeks, to layers, retired layers, and roosters? Any advice for Oz?