Broiler parent birds are genetically identical to fast-growing meat chickens but must be kept on restricted diets to prevent fatal obesity. This feed restriction causes chronic hunger — a major welfare issue.
Broiler parent welfare is perhaps the most severe systematic welfare problem in commercial poultry. These birds are hungry all their lives — not mildly, but significantly. The hunger motivation drives persistent foraging of empty litter, increased aggression, and severe frustration behaviors. The birds cannot be allowed to eat freely because their genetics would kill them through obesity and cardiovascular failure before they reach productive age. This is a welfare problem created entirely by breeding decisions made for meat chicken production. The solution is slower-growing parent stock genetics — this reduces the need for severe restriction. Some producer groups are beginning to shift but change is slow relative to the welfare urgency.