Leg disorders are the most significant and prevalent welfare problem in broiler chickens. Their direct cause is the extreme growth rate of commercial breeds.
Leg disorders in broiler chickens represent one of the largest-scale welfare problems in modern agriculture. The direct cause is well understood: extreme growth rates driven by genetic selection for rapid muscle deposition outpace the development of skeletal and cardiovascular systems. The result is birds that cannot walk properly, must rest on painful breast blisters, and experience chronic pain during their entire brief existence. Research on pain in lame broilers using analgesic tests shows that birds experience genuine pain and that pain relief improves their behaviour and welfare. The welfare solution — breeding for slower growth — is available but requires market and regulatory pressure to implement.