I’m so upset! Five of my silver apple yard ducklings from Metzer are dead. They died within an hour of showing symptoms. However, they also seemed smaller than the one left and never quite as vigorous as the one left. I bleached the brooder and all my equipment before they arrived. I do mix my own feed that my other ducks and chickens happily eat. I of course add niacin, and added rooster booster to their water(which I usually do for a week or so upon receiving chicks). The one left still s email healthy, but is very upset to be alone. However , I wouldn’t dare add another one until I know she’s healthy.