Keel bone fractures affect the majority of laying hens in cage-free and free-range systems. This painful and widespread condition is one of poultry welfare science's most pressing research priorities.
The keel bone fracture crisis represents an uncomfortable truth about cage-free systems: removing birds from cages improves some welfare dimensions while creating new ones. Battery cages prevented keel fractures by preventing flight and falls. Cage-free aviary systems that allow wing-flapping and perching create the conditions for fractures that are painful and permanent. This does not mean cage-free is worse overall — the behavioral benefits of cage-free substantially outweigh the fracture risk in welfare assessments. But the fracture problem demands solutions. Better aviary design with lower perch heights, wide landing platforms, ramps, and anti-slip surfaces reduces fracture incidence. Genetic selection for bone density and structural integrity is the medium-term solution. Until then, monitoring fracture prevalence as a welfare KPI is essential for the industry.