Selective breeding for rapid growth in broiler chickens has created serious cardiovascular welfare problems. Sudden death syndrome and ascites are common consequences of growth-selection pressure.
Cardiovascular disease in broilers is a direct consequence of breeding for maximum growth rate. Birds may die from cardiac arrest without prior clinical signs. Those developing ascites suffer from progressive fluid accumulation causing dyspnoea and abdominal discomfort over days before death. The welfare case for transitioning to slower-growing breeds is strong and increasingly supported by evidence from producers who have made the switch.