Keel Bone Fractures in Laying Hens

Keel bone fractures affect the majority of laying hens in cage-free systems, causing chronic pain. Understanding this welfare problem is essential for evaluating egg system transitions.

Key Facts

Keel bone fractures affect an estimated 50-80% of hens in cage-free aviary systems
The keel bone runs along the sternum and is the anchor point for flight muscles
Fractures occur from collisions with equipment, perches, and other hens during flight and landing
Keel fractures cause chronic pain — X-ray and palpation studies confirm high prevalence in commercial flocks
Hens with keel fractures show reduced activity, altered perching behavior, and pain responses on handling
Breed selection, perch design, and enclosure layout significantly affect keel fracture rates
Research into perch padding, ramp angles, and slower-developing breeds is reducing fracture rates in some systems

Welfare Considerations

Keel bone fractures represent a significant unresolved welfare problem in cage-free egg systems. The transition from battery cages to cage-free was a genuine welfare improvement — hens can walk, spread wings, and express natural behavior. But the high prevalence of keel fractures causing chronic pain has complicated the welfare picture. These are not rare or minor injuries: the majority of cage-free hens sustain fractures that cause ongoing pain for much of their productive lives. The welfare-optimal response is to treat keel bone fractures as a design and management challenge, not an inevitable cost of cage-free housing. Perch design improvements, slower-maturing breeds, and better flock density management all reduce fracture rates.

What You Can Do

Advocate for welfare certification schemes to include keel bone fracture monitoring as a standard metric
Support research into perch design, breed selection, and housing layout that reduces fracture rates
Choose eggs from producers that report low keel fracture prevalence alongside cage-free certification
Engage with egg producers and retailers about keel fracture monitoring and management commitments
Reduce egg consumption as a direct welfare action while industry addresses this persistent problem
Follow and share research on keel bone welfare to maintain advocacy pressure for continued improvement