Keel bone fractures affect the majority of laying hens in many commercial systems yet remain invisible to consumers and underregulated.
Keel bone fractures represent a major welfare problem that has only recently gained research attention. The keel bone (sternum) supports flight muscles and is highly susceptible to fractures during collisions with perches, slats, or other structural elements. Fractures cause acute pain at the moment of injury and chronic pain as the bone heals, often imperfectly. Hens with fractures show altered posture, reluctance to use perches, and reduced feeding activity consistent with ongoing pain. The scale of the problem - majority prevalence in many systems - makes this one of the most significant unaddressed welfare issues in commercial egg production.