Keel bone fractures affect over 50% of laying hens in some production systems, causing chronic pain that undermines the welfare case for cage-free housing as currently practiced.
The shift away from battery cages was a genuine welfare improvement in many respects — hens gained space, perches, and nesting boxes. But keel bone fractures emerged as a major unforeseen welfare problem in alternative systems. Hens with fractured keels show pain-associated behaviors, altered movement, and reduced ability to compete for resources. This is chronic pain affecting the majority of birds in systems marketed as higher welfare. Solving keel bone fractures requires breeding, housing design, and management changes that the industry has been slow to implement.