Chick culling
Chick culling is the process of killing newly hatched poultry for which the industry has no use. Due to modern selective breeding, laying hen strains differ from meat production strains. As male birds of the laying strain do not lay eggs, they are generally killed soon after they hatch and shortly after being sexed. Methods of culling include cervical dislocation, asphyxiation by carbon dioxide and maceration using a high speed grinder.
History
Prior to the development of modern broiler meat breeds, most male chickens (cockerels) were slaughtered for meat, whereas females (pullets) would be kept for egg production. However, once the industry bred separate meat and egg-producing hybrids, there was no reason to keep males of the egg-producing hybrid. As a consequence, the males of egg-laying chickens are killed as soon as possible after hatching and sexing to reduce losses incurred by the breeder. Special techniques have been developed to accurately determine the sex of chicks at as young an age as possible.