Keel bone fractures affect the majority of laying hens in enriched cages and aviary systems. This widespread painful condition represents a major unresolved welfare challenge.
Keel bone fractures represent a welfare emergency hiding in plain sight across the egg industry. With fracture rates reaching 80% in some studies of aviary hens — the system promoted as a welfare improvement over battery cages — the vast majority of laying hens may be experiencing painful skeletal injury throughout their productive lives. The chronic nature of these fractures, persisting without treatment for the remainder of the laying period, means the cumulative welfare burden is enormous. The welfare science community has raised this issue prominently, but industry and regulatory response has been slow. Solutions require attention to genetics (selecting for bone strength), nutrition (optimizing calcium), housing design (reducing collision risks), and further research into the underlying mechanisms.