Hens can literally be bred to death. You might give them more room to escape and hide to do what quail naturally do. 4 or 5 square foot per bird. Add fake or natural branches for hiding and cover, over turned flowers pots with a mouse hole cut in to isolate, if you do not use bedding you might...
I just lost a Bobwhite hen to old age. She was 8 years old. She was my oldest to survive this long. I have two boys yet that are 6 years of age and still going strong.