Hi, I am a new chicken owner. We started out with 14 sex link chickens. We thought we were doing well but at 7 weeks one of the chickens had trouble walking. After a few days we culled her. All was good for a while and then at about 12 or 13 weeks one did not look like she was feeling well during the day and we lost her the next morning. Now yesterday at 16 weeks old, we lost one and another is not looking well, lethargic and not moving much just laying in the coop. At first she was on the roost bar but moved to the floor. The other chickens are very active as usual all eating normal. It has been in the high 90s here in Arizona, and we finally had a big thunder storm yesterday. I am at a loss. We were wondering if sex link chickens have a higher mortality rate or if they cannot take the heat well? I read that some have problems when coming into the laying age.