Laying Hen Keel Bone Fractures and Cage-Free Welfare

The endemic keel bone fracture problem in cage-free laying hens and evidence-based solutions to this welfare challenge.

Key Facts

Keel bone fractures affect 50-80% of laying hens in commercial cage-free systems.
Fractures result from collision with structures, falls from perches, and bone density loss from calcium depletion.
Keel bone fractures cause chronic pain that affects laying behavior, activity, and quality of life.
Perch design including diameter, angle, and surface material significantly affects fracture risk.
Genetic selection for keel bone strength is under development as a breeding priority.
Aviary system design affects collision risk through lighting gradients, ramp placement, and perch accessibility.

Welfare Considerations

Keel bone fractures represent the primary unresolved welfare challenge of the cage-free transition. While cage-free systems dramatically improve hen welfare by enabling natural behaviors, the high prevalence of fractures creates new welfare concerns through chronic pain that affects a majority of birds in typical systems. The welfare calculation is nuanced: most welfare scientists conclude that cage-free systems with keel bone fractures still provide better overall welfare than battery cages, but the fracture problem requires active management. Solutions being implemented include improved perch design, aviary lighting that guides hen movement, genetic selection, and nutrition optimization. These improvements must be implemented alongside the cage-free transition rather than used to justify delaying it.

What You Can Do

Support cage-free egg producers that monitor keel bone fracture prevalence and implement management improvements.
Advocate for keel bone monitoring requirements in cage-free welfare certification programs.
Choose eggs from producers who document fracture prevalence and mitigation measures.
Support research into keel bone fracture prevention through genetics, nutrition, and system design.