Laying hens are among the most osteoporosis-affected vertebrates known, with bone loss accelerating through the laying cycle as calcium is mobilised for eggshell production. Structural bone disease causes fractures, pain, and compromised mobility at extraordinary prevalence.
Bone disease in laying hens is an inevitable consequence of selecting animals for extreme egg production rates that exceed the biological capacity to maintain skeletal integrity. Hens with depleted bones suffer fractures more readily during normal activity and during handling at the end of their production life. The pain associated with vertebral fractures in particular causes chronic suffering that is largely unrecognised because birds do not vocalise pain clearly. Welfare improvements require addressing the root cause — genetic selection for unsustainable production rates — alongside management improvements in housing, diet, and handling. This is an area where genuine welfare improvement requires systemic industry change rather than incremental management adjustments.