Commercial turkeys are bred for rapid breast muscle growth that causes severe welfare problems including cardiovascular disease, leg disorders, and inability to perform natural behaviors including mating.
The welfare problems of commercial turkeys stem directly from extreme selective breeding for breast muscle growth. The resulting animals are physiologically distorted: they struggle to walk, cannot mate naturally, and are at constant risk of cardiovascular failure from the metabolic demands of their own bodies. This is arguably the most severe systematic welfare harm caused by selective breeding in any farmed species. Slower-growing heritage breeds avoid these problems but remain a tiny fraction of the market. Welfare certification schemes that require slower growth rates and access to outdoor ranging for turkeys provide meaningful but partial improvement.