Modern broiler chickens have been bred for such extreme growth rates that skeletal, cardiac, and respiratory problems are near-universal, causing chronic suffering.
The welfare crisis in broiler chicken production is driven by genetics selected for extreme growth at the expense of health. Broilers carry a body mass their legs and organs are not designed to support, resulting in leg deformities, chronic pain, heart failure, and respiratory distress in a significant proportion of birds. These harms are inherent to the breed, not incidental to farming conditions. Switching to slower-growing breeds, providing enrichment, and allowing natural light and movement are the evidence-based responses. Consumer and corporate pressure is the primary driver of change.