That's your call on the preventative Corid. Given the condition of those dirty birds *I* probably would, 5 days only. It depletes them of vitamin B so not a bad idea to follow with a few days of vitamins in their water (But not at the same time as the Corid).
It is so much fun to watch chicks play and "flight train!"
It is so much fun to watch chicks play and "flight train!"