Purchased twenty five chicks from a hatchery. All were healthy and grew well. Purchased another thirty chicks. One died in transport. Next day I found two chicks dead. My chicks have been dying one or two a day for the last nine days. Same exact environment, same food...same everything, except.... There was one Cochin chick fromthe first batch that I left in with the second. Two weeks older than the second batch. Thefirst batch went into a larger brooder and are doing fine. The older chick in with the second batch was found dead yesterday.What is causing my chicks to die? I have raised a lot of chicks and have never had this problem. I am stumped! Need help figuring out how to save my remaining second batch and hope that it is not contiguous. Chicks have been on medicated chick feed. Happy and running around. No signs of illness, few hours later dead.