Modern broiler chickens reach slaughter weight in 33-35 days on genetics that cause heart disease, leg disorders, and chronic pain. Slower-growing breeds produce healthier animals with dramatically better welfare outcomes.
The welfare problems of fast-growing broiler breeds are directly and causally linked to their genetics. Selecting for rapid muscle deposition has produced birds whose cardiovascular and skeletal systems cannot keep pace with their muscle mass. Hearts that fail to pump blood efficiently to rapidly growing tissues cause sudden death — found lying on their sides with no prior illness — in a meaningful proportion of each flock. Leg disorders ranging from contact dermatitis to tibial dyschondroplasia cause pain and mobility limitation that prevents normal ranging behavior. Cognitive bias studies confirm that fast-growing broilers have more negative affective states than slower-growing birds even under identical conditions. Switching to slower-growing breeds addresses these welfare harms at their source — a solution that is commercially available, increasingly economically viable, and ethically compelling.