I have 16 Cornish Roasters that are 7 weeks old. My husband fed and watered them yesterday morning and everything was fine. He went back later in the afternoon and found 4 of them dead. There were no marks or anything that was evident that might explain what happened to them. So far, the others seem to be doing fine. Can anyone give me any ideas as to what may have happened and what I need to watch for with the others? This is my first experience with chickens and I'm trying to learn. I wasn't prepared for this to affect me so much; kinda feel like giving up now.