Why can't the other birds have the medicated feed? I thought it was to help protect them from coccidia? I only feed the medicated to the chicks for a few weeks then switch them to the regular feed. I also feed flock raiser with oyster shells free choice because I have so many different age groups. Don't know if it's the best feed or not or if it has any GMO or soy in it...I need to check, but my hens are healthy and the eggs are good and shells are strong and the chicks that hatch are fine.
Ducks and geese eat more feed for their body weight and get overdosed on the medicine. This can cause problems and death.