Keel bone fractures affect more than half of all laying hens in aviary and furnished cage systems, representing a massive and largely invisible welfare crisis in egg production.
Keel bone fractures are largely invisible to producers and consumers — hens continue to eat and lay eggs despite significant skeletal pain. Behavioural indicators include a reluctance to fly up to perches, altered posture and a penguin-like gait. Pain sensitivity tests confirm that hens with fractured keels have elevated pain threshold responses consistent with chronic pain compensation. The scale — affecting the majority of laying hens in higher-welfare systems — makes keel fractures arguably the single greatest acute welfare problem in European egg production.