Keel bone fractures are the most prevalent welfare problem in laying hen flocks globally. The condition causes chronic pain for millions of birds and is linked to housing systems, genetics, and management.
Keel bone fractures represent the paradox of welfare reform in egg production: cage-free systems introduced to address battery cage welfare problems have revealed a different but equally serious welfare challenge. The transition to perch-using cage-free systems increased opportunities for falls and collisions causing keel bone fractures. The scale of affected birds, combined with the chronic pain associated with fractures, makes this the numerically most significant welfare problem in the laying hen industry. Research into perch design, height, cushioning, and lighting that reduce fall frequency offers practical mitigation. Genetic selection for stronger keel bones alongside improved production traits represents the longer-term solution. The welfare burden of fractures must be incorporated into honest assessments of cage-free system welfare.