Hi everyone! need a bit of advice. I have 5 2 1/2 week old aussie chicks from Cackle Hatchery. They are doing great but here's my dilemma. I was only able to get ahold of Nutrena medicated chick starter originally so i went with it and have been feeding them that. I now have a bag of Nutrena UNMEDICATED. When and how can I switch them off the medicated stuff???