Keel bone fractures affect the majority of laying hens in cage-free and free-range systems, causing chronic pain and representing one of the most prevalent welfare problems in commercial egg production.
Keel bone fractures represent a major welfare paradox in egg production reform. The welfare improvements of cage-free systems - space for movement, perching, and social behaviour - come with a welfare cost that was not fully anticipated: dramatically higher keel bone fracture rates from increased activity. This does not mean cage-free is worse than caged systems overall - the welfare balance still favours greater freedom - but it highlights that welfare improvement is rarely simple. The fractures cause chronic pain that affects behaviour throughout the laying period. Solutions require intervention at multiple levels: genetic selection for stronger keel bones, perch design that reduces collision injury, management to reduce fall distance, and lighting programmes that reduce frantic movement.