Chick culling is the process of killing newly hatched poultry for which breeders have 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 and are not suitable for meat production, they are generally killed soon after they hatch. Most of the male chicks are usually killed shortly after being sexed. Methods of culling include cervical dislocation, asphyxiation by carbon dioxide and maceration using a high speed grinder.
Prior to the development of modern meat breeds, most male chickens (cockerels) would usually be slaughtered for meat, while females (pullets) would be kept for egg production. However, once farmers bred separate meat and egg breeds, it became apparent that there was no reason to keep males of the egg breed alive. As a result the males of every 'batch' of egg-laying chickens would be killed as soon as possible to reduce losses incurred by the breeder through the feeding and sheltering of them. Special techniques were developed to accurately determine the sex of chicks at as young an age as possible.
The culling of unwanted chicks
In industrial factory farms, chicks that are not intended for rearing are culled shortly after their sex is determined, usually before they are 72 hours old. About 200 million male chicks are killed each year in the United States.
Several methods have been used to kill chicks:
- Maceration, using a large high-speed grinder into which the live chicks are fed.
- Gases or gas mixtures, often carbon dioxide is used to induce unconsciousness and then death.
- Cervical dislocation (breaking the neck)
- Electrocution, a new method that has been touted as being cheap, reliable, and humane by its developers 
Recommended culling practices
The 2005-2006 American Veterinary Medical Association Executive Board held its final meeting July 13 in Honolulu, prior to the 2006 session of the House of Delegates and the AVMA Annual Convention. It proposed a policy change, which was recommended by the Animal Welfare Committee on disposal of unwanted chicks, poults, and pipped eggs. The new policy states, in part, "Unwanted chicks, poults, and pipped eggs should be killed by an acceptable humane method, such as use of a commercially designed macerator that results in instantaneous death. Smothering unwanted chicks or poults in bags or containers is not acceptable. Pips, unwanted chicks, or poults should be killed prior to disposal. A pipped egg, or pip, is one where the chick or poult has not been successful in escaping the egg shell during the hatching process."
Animal rights activists maintain that many of the current practices surrounding chicken slaughtering are unethical.
- Hatchery Horrors: The Egg Industry's tiniest victims. Mercy for Animals. (includes graphic video on culling)
- New Investigation Reveals Horrific Cruelty at 'Humane' Chicken Hatchery.
- 6 Crimes Against Nature Perpetrated By the Food Industry