Parent breeds of broiler chickens must be severely feed-restricted to prevent obesity and health problems that would otherwise prevent reproduction, causing chronic hunger.
Broiler parent welfare is one of the most ethically troubling aspects of poultry production. Animals selected for extreme growth traits must be kept chronically hungry throughout their productive lives to remain reproductively viable — they are, in effect, the welfare victims of the traits being reproduced. Research consistently shows that restricted breeders experience significant chronic distress from hunger, and the behavioral expression of this distress is clear. High-fiber diet programs that allow fuller feeding with similar health outcomes represent a genuine improvement, but the root cause requires genetic selection changes.