Keel bone fractures affect a majority of laying hens in both cage-free and enriched cage systems, causing chronic pain that represents one of the most prevalent unaddressed welfare problems in the egg industry.
Keel bone fractures represent a hidden welfare epidemic in laying hens. Unlike cage battery systems where behavioral deprivation is the primary welfare deficit, cage-free systems can improve behavioral welfare while introducing a high prevalence of painful physical injury. The transition from cages to cage-free was welfare progress, but it did not solve the welfare challenge — it changed its character. Addressing keel bone fractures requires attention to perch design, breed selection, and housing geometry. This illustrates an important welfare principle: welfare improvements in one dimension can coexist with welfare problems in another, requiring ongoing attention rather than certification as a completed achievement.