The global transition away from conventional battery cages represents the largest animal welfare policy shift in history, but the alternatives have their own welfare trade-offs.
The cage-to-cage-free transition improves some welfare outcomes significantly — freedom of movement, expression of foraging and nesting behaviors — while creating new welfare challenges. Keel bone fractures from falling and colliding in multi-tier aviaries affect the majority of cage-free hens and cause chronic pain, yet are largely invisible to consumers. Feather pecking and cannibalism increase in cage-free systems without appropriate management. Furnished cages, while still confining, can outperform poorly managed cage-free systems on bone health. The welfare ideal combines the space and movement benefits of cage-free with management practices that minimize pecking injuries and fractures: adequate perch design, appropriate light management, and lower stocking densities.