Egg-laying hens are typically only kept on an egg farm for one year after they have started laying eggs, and sometimes two years. Although they are still physically able to lay eggs past two years, and their natural life span is much longer (5-11 years), the number of eggs hens lay per year greatly decreases after one year of lay, as does the quality of the egg shell and its contents. At that point, the chicken is considered to be a “spent hen” and is sent for slaughter.
Commercial laying hens are bred to produce high quality eggs. Meat quality (muscle mass) is not a focus in the egg industry, so egg-laying hens tend to have very little muscle mass compared to their meat-bird cousin, the broiler chicken, who has been bred over generations to produce a lot of muscle (mostly breast meat) in a short 6-8 week time span.
Since the meat from laying hens is considered to be of poor quality, it is typically used in canned products like soups, or for pet food.