Broiler chickens are the single largest source of farmed animal suffering. Welfare improvements at this scale have enormous impact, and breed selection is one of the highest-leverage interventions available.
No single intervention could improve animal welfare at a larger scale than transitioning the global broiler industry from fast-growing to slower-growing breeds. The health problems endemic in fast-growing commercial breeds — skeletal deformities, ascites, heart failure — affect billions of animals and are a direct product of breed selection for maximum growth speed. The Better Chicken Commitment, which includes breed, space, enrichment, and slaughter standards, represents the most comprehensive industry-scale welfare reform currently pursued.