Hen Keel Bone Fractures: An Overlooked Welfare Crisis

Keel bone fractures affect the majority of laying hens in European non-cage systems. They cause chronic pain and represent one of the most numerically significant unremedied welfare problems.

Key Facts

The keel bone (sternum) is central to the laying hen's chest anatomy; fractures and deviations are extremely common in commercial flocks.
Studies using radiography and palpation report keel bone fracture prevalence of 50-80% in European laying hens in enriched and non-cage systems.
Fractures cause chronic pain: hens with experimentally induced keel fractures show altered behaviour consistent with pain.
Risk factors include hen genetics, housing features (perch height and design), flock density, and management.
Fractures accumulate over the laying period; by end-of-lay, prevalence approaches 100% in some flocks.
Research has identified perch design as critical: round metal perches at inappropriate height cause more fractures than oval or wooden perches at appropriate locations.
Genetic selection for keel bone robustness is being actively pursued; some breeding companies are incorporating keel integrity into selection indices.
Despite its prevalence and welfare significance, keel bone health is not routinely monitored on commercial farms in most countries.

Welfare Considerations

Keel bone fractures represent arguably the largest unaddressed welfare problem in European poultry farming. The welfare transition from battery cages to enriched and free-range systems — motivated by legitimate welfare concerns about cage confinement — inadvertently created a new welfare problem as birds with bones adapted to low-activity cage life began to engage in flight and perch use that their bones could not withstand. The result is that the majority of laying hens in the higher-welfare systems now live with chronic pain from keel fractures. Addressing this requires a multi-pronged approach: genetic selection for keel bone strength, housing design improvements, and routine monitoring. The near-absence of keel bone health from welfare certification standards and public awareness is a significant gap that welfare advocates and scientists are working to close.

What You Can Do

Support welfare certification schemes that incorporate keel bone health monitoring.
Advocate for research and regulatory attention to keel bone fractures in laying hens.
Support breeding programmes that include keel bone integrity in selection criteria.
Raise awareness that even free-range eggs may come from hens with significant welfare compromise.
Support research into housing modifications that reduce keel fracture incidence.
Engage with poultry welfare consultations to prioritise keel bone health as a welfare indicator.