I lost interest in production reds long ago because of their generally 'feisty' attitudes toward other flock members. I've never had sex- links, because I prefer heritage type breeds, and when ordering from hatcheries, most often get straight run chicks. I can eat or sell excess cockrels, always have some cocks in my flock, and am NOT a fan of what happens at some hatcheries with excess cockrels. That will include ALL sex- linked males at hatching. That's the point of producing sex- links in the first place. Okay, rant over! It's impossible to predict how long an individual hen will stay healthy and in lay, and that's equally true of heritage birds. It depends on husbandry, genetics, and luck. Mary