Brethren - sincere best wishes for your family as your husband recovers!
Greenmimama - Michigan State Univ. Veterinarians told me at the Poultry workshop in the spring to wean off the medicated starter like this-
Week 6 - 100% medicated feed
Week 7 - 75% medicated feed and 25% non medicated
Week - 50% medicated feed and 50% non medicated
Week 9 - 25% medicated feed and 75% non medicated
Week 10 -
non-medicated feed
The idea is that as the chicks get exposed to the parasites your big chickens might have - they have the medicated feed which allows them to not get too sick and allows them to build some immunity. Hope that helps!