Modern commercial turkeys have been selectively bred for such rapid breast muscle growth that many cannot breed naturally and suffer significant musculoskeletal problems throughout their shortened lives.
The extreme selection for meat yield has created a bird anatomically unsuited to its own life. Cardiovascular strain, hip joint problems, and difficulty with normal locomotion are endemic to commercial breeds. Welfare improvement requires moving away from the genetic arms race toward breeds that can express natural behaviours, mate normally, and maintain physical soundness.