Poultry Keel Bone Fractures: An Urgent Cage-Free Welfare Challenge

Keel bone fractures affect the majority of laying hens in cage-free systems, causing chronic pain. Addressing this is one of the most urgent priorities in commercial egg production welfare.

Key Facts

Studies consistently find keel bone fractures in 50-80% of hens in commercial cage-free aviary systems
The keel bone (sternum crest) is the largest bone in the bird's body — fractures cause significant, long-lasting pain
Fractures occur primarily from collisions with housing structures when birds fly or drop between levels
Conventional battery cages had lower keel bone fracture rates but prevented almost all natural behaviour
Selective breeding for bone strength, improved perch design, and modified ramp angles can reduce fracture incidence
Hens with keel bone fractures show pain behaviours and analgesic responsiveness confirming welfare impact

Welfare Considerations

Keel bone fractures represent one of the most significant welfare failings in cage-free egg production. The transition from battery cages was a genuine welfare advance, but it introduced a new and serious welfare problem that was not adequately anticipated. Hens with keel bone fractures experience chronic pain — validated by pain scoring and analgesic studies. Addressing this requires investment in housing design, genetic selection, and management practices rather than acceptance as an inevitable feature of cage-free systems. The welfare of cage-free hens must continue improving, not plateau at a point still involving widespread chronic pain.

What You Can Do

Ask egg producers and retailers specifically about keel bone fracture rates and their reduction strategies
Support certification schemes that include keel bone welfare monitoring as an outcome measure
Advocate for investment in housing design improvements specifically targeting keel bone fracture reduction
Support research into genetic selection for bone strength in laying hen lines
Keep pressure on the industry to continue improving cage-free welfare beyond the baseline