Leg disorders are among the most significant welfare problems in commercial broiler production, affecting millions of birds with painful lameness caused by the unsustainable growth rates selected for in modern commercial breeds.
Leg disorders in commercial broilers represent a direct welfare consequence of selective breeding for extreme growth rates without commensurate attention to skeletal system development. The musculoskeletal system of fast-growing commercial breeds simply cannot develop at the rate that growth selection demands, resulting in bones and cartilage that are structurally compromised in a significant proportion of birds. Lame broilers experience chronic pain throughout their final weeks of life, spending more time lying in litter that causes further welfare problems through pressure sores and contact dermatitis. The welfare solution is structural rather than managerial: transitioning to slower-growing breeds that are physiologically capable of developing more robustly is the only intervention that addresses the root cause rather than managing its consequences. Welfare assessments using gait scoring provide the outcome data needed to drive breed selection improvements through market signals and regulatory requirements.