Keel bone fractures affect the majority of laying hens in commercial systems, causing chronic pain throughout the production period. This is one of the most significant unresolved welfare problems in egg production.
Keel bone fractures represent one of the most significant and underappreciated welfare problems in egg production. The keel bone is the large central breastbone of birds, and in laying hens it experiences high mechanical loads during movement combined with reduced bone density from calcium demands of eggshell production. The resulting fractures — occurring in the majority of commercial hens in many systems — cause chronic pain throughout the bird's life. Research using analgesic tests shows that hens with fractures change behaviour when given pain relief, confirming that the fractures are genuinely painful. Current welfare standards provide no specific protection against keel bone fractures.