Production hens......brown hybrid egg layers I understood to be 'old' at 2-3 and to die aged at 4 or under. I am talking about the Hyline. ISA Brown, Warren type......bred to lay eggs and to never be broody etc. Well here's Warrren......aged 6 years and 5 months......I've owned her ever since she was POL (never been confined in any way). She stopped laying in August /September2011, having laid about 5 eggs per week for 5 years. I thought she had entered her retirement. Then at the end of February 2012 she began to lay again....perfect eggs...about 4 per week....laid in the same place in about 30 seconds. Warren looks fit, feels heavy, is feisty ....and well, just looks much younger than she is. She has a 5 plus daughter (Warren xBrahma) who is also an excellent layer. Maybe some genetic superiority?