Keel Bone Fractures in Laying Hens

Keel bone fractures are among the most prevalent and painful welfare problems in laying hens, affecting the majority of birds in cage-free and aviary housing systems.

Key Facts

Keel bone fractures affect an estimated 50-80% of laying hens in cage-free systems, making them one of the most common welfare problems in poultry.
The keel bone is the large breastbone to which major flight muscles attach; fractures occur from collisions, falls, and landing impacts.
Hens with keel fractures show pain behaviours including reduced movement, altered posture, and sensitivity to touch.
Paradoxically, cage-free and aviary systems — promoted for better welfare than battery cages — have higher keel fracture rates due to greater bird movement.
Selective breeding for egg production has prioritised egg output over bone strength, increasing fracture susceptibility.
Perch design, ramp angles, and lighting management can reduce fracture rates by minimising collision and fall risk.
Current assessment at slaughter shows fracture prevalence but does not capture the duration of pain experienced during the laying period.
Some breeds show lower fracture prevalence, suggesting genetic selection as a longer-term solution.

Welfare Considerations

Keel bone fractures represent one of the most uncomfortable findings in farm animal welfare science: the shift to cage-free housing, broadly celebrated as a welfare improvement, has inadvertently increased the prevalence of a painful bone injury. This does not mean cage-free systems are worse overall — they offer important improvements in space, behaviour expression, and movement — but it reveals that welfare is multi-dimensional and that improving one domain can create problems in another. Addressing keel bone fractures requires investment in better housing design, genetic selection for bone strength, and management practices that reduce collision risk, not a retreat to battery cages.

What You Can Do

Support welfare schemes that specifically address keel bone fracture prevention, not just cage-free status.
Advocate for research funding into laying hen breeds with improved bone strength.
Encourage egg producers to measure and report keel bone fracture prevalence in their flocks.
Choose eggs from producers who have adopted low-fracture housing designs with appropriate ramps and perch heights.
Engage with egg retailers to include keel bone welfare in their hen welfare commitments.