Bone fractures and osteoporosis are major welfare problems in laying hens, driven by calcium mobilisation for eggshell production — and perch access plays a critical role in maintaining bone strength through exercise.
Laying hen bone welfare represents one of the most prevalent and poorly recognised welfare problems in modern poultry systems. The physiological conflict between calcium allocation to eggshell versus skeleton is intrinsic to the laying hen body under high production pressure — breeds selected for 300+ eggs per year face a metabolic calcium demand that the skeleton cannot sustain without resorption. Perch access partially compensates for this by maintaining cortical bone strength through mechanical loading. However, perch design is critical: poorly designed perches cause keel bone deformities as hens land awkwardly, footpad lesions from improper gripping surfaces, and access inequality where dominant birds monopolise perch space. Fractures that occur during depopulation (catching) add acute injury to chronic bone weakness. The welfare solution requires both better perch provision and breeding selection away from extreme egg production rates that impose unsustainable skeletal calcium demands.