Chick culling is the process of killing newly hatched poultry for which the industry has no use. It occurs in all industrialised egg production whether free range, organic, or battery cage—including that of the UK and US. Because male chickens do not lay eggs and only those on breeding programmes are required to fertilise eggs, they are considered redundant to the egg-laying industries and are usually killed shortly after being sexed, which occurs after they hatch. Many methods of culling do not involve anaesthetics and include cervical dislocation, asphyxiation by carbon dioxide and maceration using a high speed grinder. Asphyxiation is the primary method in the United Kingdom, while maceration is the primary method in the United States. By 2020, US producers expect to sex the eggs before they hatch, so male eggs can be culled.
Due to modern selective breeding, laying hen strains differ from meat production strains (broilers). In the United States, males are culled in egg production, since males "don’t lay eggs or grow large enough to become broilers".
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[when?] 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.
As of 2018, worldwide around 7 billion day-old male chicks were culled per year in the egg industry.
Chicks are also culled in the production of foie gras. After hatching, the ducklings are sexed. Males put on more weight than females, so the females are killed, sometimes in an industrial macerator. Up to 40 million female ducks per year may be killed in this way. The remains of female ducklings are later used in cat food, fertilisers and in the pharmaceutical industry.
Several methods are used to cull chicks:
- Maceration; the chicks are placed into a large high-speed grinder.
- Cervical dislocation; the neck is broken.
- Electrocution; an electric current is passed through the chick's body until it is dead.
- Suffocation; the chicks are placed in plastic bags.
- Gases or gas mixtures; carbon dioxide is used to induce unconsciousness and then death.
US recommended methods
The American Veterinary Medical Association recommends cervical dislocation, maceration, and asphyxiation by carbon dioxide as the better options. The 2005-2006 American Veterinary Medical Association Executive Board proposed a policy change, which was recommended by the Animal Welfare Committee on disposal of unwanted chicks, poults, and pipped eggs. The policy states "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 welfare advocates maintain that many of the current practices surrounding chicken slaughtering are unethical. Animal rights advocates maintain that it is unethical to unnecessarily exploit and kill other sentient beings for food production, including chicks. 
A Unilever spokesperson has been quoted as saying "We have also committed to providing funding and expertise for research and introduction of alternative methods such as in-ovo gender identification (sexing) of eggs. This new technology offers the potential to eliminate the hatching and culling of male chicks."
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