Broiler chickens are the most numerous farmed animal on Earth. Selective breeding for rapid growth has created widespread chronic pain and locomotion problems across the industry.
The welfare crisis in commercial broiler production is rooted in genetics. Fast-growing breeds have been selected for breast muscle growth that outpaces skeletal and cardiovascular development, causing contact dermatitis, heart failure (sudden death syndrome), and painful musculoskeletal disorders. A broiler that cannot walk cannot escape pain or access food and water. The animals experience these conditions for the final weeks of a short but pain-filled life. Crowded sheds with poor litter quality compound locomotion problems. Higher-welfare breeds and improved management can dramatically reduce these harms.