I have 4- 1 year old hens and 12- 8 week old hens. My question is related to medications. I don't want to give my chickens any unnecessary medications but I also don't want health issues because I did not give them what they need. They all eat grower feed supplemented with oyster shells but I have never medicated them at all. They are all very healthy and happy and there are no concerns on the surface. What are the concerns and recommendations for not medicating? Is medication required? Thanks for any input you all may have.