Keel bone fractures are the defining welfare problem of cage-free egg production. Advanced research into causes, prevention, and detection is transforming understanding of this critical issue.
Keel bone fracture science has advanced significantly in understanding that this is not an inevitable consequence of cage-free systems but a solvable engineering and genetics problem. The fracture cascade — bone mineral depletion from sustained egg production, weakened keel bones, landing collisions in multi-tier systems — can be interrupted at multiple points. Breeding programs that maintain better bone density throughout the laying period, enclosure designs that reduce the height and angle of landing forces, and nutrition protocols that better support bone mineralization all reduce fracture rates. The most important message for welfare advocates is that cage-free systems are still clearly preferable to conventional battery cages on most welfare dimensions, but the keel bone problem demands urgent attention and ongoing investment — it cannot be dismissed as an acceptable trade-off.