Keel bone fractures affect the majority of hens in most laying systems, causing chronic pain that makes this one of the most prevalent and under-addressed welfare problems in poultry.
Keel bone fractures represent one of the most significant welfare challenges in the transition from caged to cage-free laying hen systems. While cage-free systems are unambiguously better for behavioral welfare, the multilevel aviaries that replaced cages have introduced a new welfare problem at even greater scale: collision and fall injuries during movement through the housing. The majority of hens in some aviary systems live with painful fractures throughout their laying lives. This is not an argument against cage-free transitions — it is an argument for investing in housing design, genetics, and management that reduce fracture incidence in cage-free systems.