The genetic selection of modern broiler chickens for rapid growth and high breast meat yield has created significant welfare problems. Slow-growth breeds offer a welfare-positive alternative, growing to market weight more slowly but with substantially better health and behavioral outcomes.
Welfare Problems in Fast-Growth Broilers
Conventional broilers are selectively bred to reach market weight in approximately 35 days, growing at rates that their cardiovascular and musculoskeletal systems cannot adequately support. As a result, broilers suffer disproportionately from leg disorders, including angular limb deformities, tibial dyschondroplasia, and hock burn from lameness-associated sitting. Studies estimate that 25-30% of commercial broilers experience moderate or severe lameness, causing significant pain and limiting their ability to access feed and water.
Metabolic diseases including ascites and sudden death syndrome are more prevalent in fast-growth breeds. The high oxygen demand of rapidly growing muscle mass stresses the cardiovascular system, and the enlarged chest musculature limits the ability of broilers to rise from prone positions — a welfare problem termed flip-over or leg weakness.
How Slow-Growth Breeds Differ
Slow-growth breeds typically reach market weight in 56 days or more, growing at rates their bodies can accommodate. This longer production period results in lower rates of leg disorders, reduced prevalence of metabolic disease, better gait scores, and higher activity levels. Research comparing fast and slow-growth breeds under identical conditions consistently finds welfare advantages in slower-growing birds.
Slow-growth broilers also show higher engagement in species-typical behaviors including foraging, perching, and dustbathing, which require adequate mobility and reflect higher behavioral welfare. Their more robust immune systems support better disease resistance, reducing mortality and the need for veterinary intervention.
Industry and Retail Commitments
Major food service companies and retailers have made commitments to source broilers meeting higher welfare standards, including use of breeds that achieve better outcomes on gait scoring, activity, and leg health. The Better Chicken Commitment framework, adopted by hundreds of companies globally, includes breed criteria alongside requirements for enrichment, outdoor access, and stocking density.
Economic Considerations
Slower growth requires longer production periods and more feed per unit of meat produced, increasing costs. This cost difference must be reflected in product pricing or absorbed in supply chain efficiency. Consumer research indicates willingness to pay premiums for higher-welfare poultry products, providing a market pathway for slow-growth broiler systems.
2025 Progress Report
As of 2025, major progress has been made in corporate commitments to slow-growth breeds in Europe, North America, and Australia. Implementation is advancing in the UK and Netherlands, with significant market share now meeting higher breed welfare criteria. Supply chain development challenges remain in markets with smaller premium segments, but the trajectory toward higher-welfare breed use continues.