Commercial turkeys have been so heavily selected for breast muscle that they face significant welfare challenges including cardiovascular disease, leg problems, and inability to mate naturally.
The commercial turkey has been redesigned through breeding to such an extreme that the animal can no longer function as a normal bird. Unable to mate, prone to cardiovascular collapse, and challenged to support its own weight, the commercial turkey experiences chronic welfare compromise. This is analogous to the brachycephalic dog problem in companion animals — welfare failure designed in at the genetic level. Heritage breeds represent both a welfare improvement and a connection to what turkey biology can look like when not pushed to extremes.