Laying hens experience high rates of bone fractures from osteoporosis caused by calcium depletion during egg production, with significant welfare implications across all housing systems.
Laying hen bone fractures represent one of the most widespread, poorly recognised welfare problems in animal agriculture. The scale is enormous - billions of hens experience fractures, and many live with chronic bone pain for weeks or months before slaughter. Fractures occur in all housing systems, though rates differ: keel fractures are higher in aviary/cage-free systems (from flying and landing), while other fractures are higher in conventional cages. There is no housing system that eliminates fractures entirely with current genetics and production systems. Welfare improvement requires genetic selection for bone quality, dietary management, housing design that reduces collision risk, and earlier slaughter before bone depletion becomes severe.