They were four years old......as to breed, um....well, one was red, one was black. We feed them a layer food from a local farmer plus a variety of treats, dried worms and earthworms. This batch of chickens is our third over the last six or seven years. Others have died of old age, but these were the first to die within a few days of each other. We just want to be sure the eggs we harvest are edible. These were p[art of our latest batch of chicks from four years ago. No noticeable change in any behavior,