Osteoporosis and bone fractures are among the most prevalent and painful welfare problems in laying hens, driven by the metabolic demands of high-rate egg production on skeletal calcium reserves.
Osteoporosis in laying hens is a disease of production — the biological cost of producing 300+ eggs per year on a skeletal system that cannot maintain bone density at that rate of calcium mobilization. Hens with keel bone fractures experience chronic pain with every movement, yet continue to be housed in conditions requiring significant locomotion to access food, water, and enrichment resources. The pain from fractures is invisible to casual observation but measurable through behavioral indicators. The root cause is genetic selection for egg production rate without proportional improvement in calcium metabolism or skeletal strength. Lower-production breeds and nutritional interventions can partially address the problem.