Whenever I ask my feed store or a local chicken breeder (or even look at the back of the bag recomendations) how long to feed the Medicated Starter they tell me until the chickens are 4 months old. Wow-they are only 9 weeks old. I worry about the de-wormer or antibiotics in the medicated feed contaminating their eggs when they begin laying. Even now, the chickens prefer foraging in the chicken tractor all day...Good for them! At night (in the coop) they have medicated starter crumbles as well as seeds/grains/sunflower seeds that I've combined to add to their diet...this is also available all day, but they hardly touch it. They seem healthy, but I'm having concerns about feeding them the medicated stuff and even wondering how safe their eggs will be with ANY commercial feed? I can't afford to buy all organic, but is the commercial feed absolutely necessary for healthy chickens?