Our poultry didn't last more than a year either, and we weren't factory farming. We bought 15 chicken every year, 3 male to eat before they were fertile early spring, 12 female that we ate during the next winter. And half a dozen rabbits too. Then my grandparents grew too tired and started to travel instead of farming/taking care of poultry.

The animals might have been happy (or, at least happier than in a factory farm), but clearly their life were short.