The extreme calcium demands of commercial egg production cause severe osteoporosis in laying hens, leading to painful bone fractures that affect a significant proportion of commercial flocks throughout and at the end of their productive lives.
Bone fractures in laying hens represent one of the most underappreciated welfare crises in food production. The fractures - occurring during normal activity, catching on cage or barn equipment, or during the rough handling of depopulation (catching and crating) - cause acute pain that significantly affects behavior. Hens with fractured keel bones (the breast bone) avoid wing flapping and flying, reducing their ability to access elevated perches and resources in enriched environments. The chronic pain from unhealed fractures persists throughout the remaining laying period. At slaughter, the rough handling during depopulation causes additional fractures in already osteoporotic birds. The welfare cost is compounded by the impossibility of identifying and treating individual birds with fractures in commercial flocks.