Parent breeding flocks of commercial chickens are chronically food-restricted to prevent the health problems caused by their rapid-growth genetics.
Broiler parent birds experience a lifetime of chronic hunger that studies describe as comparable to conditions used in controlled starvation experiments. Breeding for extreme growth has created a genetic catch-22: unrestricted feeding causes premature death from cardiovascular collapse, while restricted feeding causes a lifetime of frustrated hunger. This represents a systemic welfare failure built into commercial poultry genetics.