Laying hens suffer among the highest rates of bone disease of any farmed animal, driven by calcium mobilisation for eggshell production and inadequate opportunity for weight-bearing exercise.
The epidemic of bone disease in commercial laying hens represents a chronic, industry-scale welfare failure that is directly produced by the intersection of selective breeding for high egg output and inadequate movement opportunity. Each egg requires significant calcium that the body withdraws from bones if dietary intake is insufficient. Hens confined in systems that prevent exercise cannot maintain bone density through weight-bearing activity. The result is structural weakness, fracture risk, and chronic pain affecting enormous numbers of birds. Addressing laying hen bone health requires reformed breeding goals, improved housing systems that allow exercise, perch design improvements, and dietary calcium optimisation — a multi-dimensional challenge with major welfare stakes.