I've had a problem with my Jubilee Orpington chicks. They start out fully robust but over time seem to be weaker than my other breeds and if there is a dead chick in the brooder it seems like more often than not it is a Jubilee. Now I have noticed fewer losses when I hold them back a week and raise them with younger chicks so one theory was that they are easily bullied and run over but I'm not sure if that's a good reason. I've heard that Green Junglefowl are more susceptible to coccidiosis and I've seen where a breeder who raises Tomaru has stated that they seem weaker as chicks and raise them in separate brooders but that they are fine and healthy as adults. I was wondering if some breeds (maybe due to inbreeding...or maybe just lines that are inbred) have weaker immune systems and more likely to have issues with coccidiosis. Are there other things that would cause one breed of chicks to do poorly while all the breeds of adults including that breed seem fine and healthy and all the chicks other than that breed do fine?