Commercial broiler chickens have been selectively bred for rapid growth to an extent that compromises their welfare. The shift to slower-growing breeds is the most significant structural welfare improvement available.
The welfare problems of commercial broiler chickens are substantially caused by the genetics of the birds themselves — the extreme selective pressure for rapid growth has created animals whose bodies are fundamentally poorly suited to the lives they lead. Lameness from skeletal abnormalities, heart failure from cardiovascular systems overwhelmed by rapid muscle growth, and respiratory compromise from chest muscle mass impinging on breathing are all intrinsic to the fast-growing phenotype rather than contingent management failures. Slower-growing breeds — while more expensive to produce due to longer feeding periods — have demonstrably better welfare outcomes by every measurable indicator. The Better Chicken Commitment represents the most significant structural welfare initiative in commercial poultry history because it targets the root cause rather than managing symptoms.