Laying hens suffer high rates of osteoporosis and bone fractures caused by the physiological demands of intensive egg production. This widespread welfare problem is linked to housing systems and genetics.
Laying hen bone fractures represent one of the most widespread yet underappreciated welfare problems in animal agriculture. The physiological demands of producing hundreds of eggs per year deplete skeletal calcium to the point that hens become profoundly osteoporotic. Fractures — confirmed by post-mortem studies — occur at astonishing rates; many hens at slaughter have multiple healed fractures indicating injuries sustained during their laying lives. Fractures during live catching and shackling at slaughter cause acute pain at the end of life. Housing systems that allow movement improve bone strength, but even free-range hens commonly suffer high fracture rates. Addressing this requires changes to genetics, housing, handling practices, and slaughter methods simultaneously.