Keel bone fractures affect up to 80% of laying hens in cage-free systems, causing chronic pain and representing one of the most urgent unsolved welfare problems in modern egg production despite industry transition away from cages.
Keel bone fractures in laying hens cause chronic pain that persists for the lifetime of the fracture — which in many cases means most of the laying period. Affected hens modify their behaviour in ways that reflect pain: reduced jumping, altered landing posture, and preference for lower-tier access. The scale of this problem is extraordinary — in transitioning away from cages to improve welfare, the industry has inadvertently created a new, large-scale source of chronic pain affecting the majority of birds in the most common cage-free system. Addressing keel bone fractures requires simultaneous attention to genetics, nutrition, rearing conditions, and housing design — no single intervention resolves the problem.