The selective breeding of broiler chickens for extreme growth rates has created birds whose bodies cannot support their own weight, causing widespread chronic pain and health problems that affect billions of animals annually.
The welfare cost of extreme growth genetics is borne by billions of birds annually. Lameness affects the majority of commercial broilers to some degree; severe lameness impairs the ability to walk, eat, drink, and perform basic behaviours. Sudden death syndrome and ascites kill significant proportions of flocks before slaughter. The pain of walking on damaged joints affects every moment of a lame bird's life. Breed reform - transitioning to slower-growing breeds with better leg health - is one of the highest-impact single interventions available in farm animal welfare.