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A hatchery is a facility where eggs are hatched under artificial conditions, especially those of fish or poultry. It may be used for ex-situ conservation purposes, i.e. to breed rare or endangered species under controlled conditions; alternatively, it may be for economic reasons (i.e. to enhance food supplies or fishery resources).
Fish hatcheries 
Fish hatcheries are used to cultivate and breed a large number of fish in an enclosed environment. Fish farms use hatcheries to cultivate fish to sell for food, or ornamental purposes, eliminating the need to find the fish in the wild and even providing some species outside of their natural season. They raise the fish until they are ready to be eaten or sold to aquarium stores. Other hatcheries release the juvenile fish into a river, lake or the ocean to support commercial, tribal, or recreational fishing or to supplement the natural numbers of threatened or endangered species, a practice known as fish stocking.
Researchers have raised concerns about hatchery fish potentially breeding with wild fish. Hatchery fish may in some cases compete with wild fish. In the United States and Canada, there have been several salmon and steelhead hatchery reform projects intended to reduce the possibility of negative impacts from hatchery programs. Most salmon and steelhead hatcheries are managed better and follow up to date management practices to ensure any risks are minimized.
Poultry hatcheries 
Poultry hatcheries produce a majority of the birds consumed in the developed world including chickens, turkeys, ducks and some other minor bird species. It is a multibillion dollar industry, with highly regimented production systems used to maximize bird size versus feed consumed. Birds are produced and maintained under high density, which makes production and harvesting more economical, but can also generate problems such as the spread of pathogens, which can move very quickly through the population when animal densities are high.
Poultry generally start with naturally (chickens) or artificially (turkeys) inseminated hens that lay eggs; the eggs are cleaned and shells are checked for soundness before putting them in the incubators. The incubators control temperature and humidity, and turn the eggs until they hatch. Generally large numbers are produced at one time so the resulting birds are uniform in size and can be harvested at the same time. Once the eggs hatch and the chicks are a few days old, they are often vaccinated, beak-trimmed and or toe-clipped; this involves the removal of half of the top beak and the clipping of the toe ends. This is done to prevent the birds from harming each other while they are living in close proximity to each other. After these procedures, they are moved to enclosed buildings to be raised until harvest.
For chickens bred as (egg) layers, only the female chicks are considered to be of value; in excess of 100,000 male chicks can be dropped into an industrial "grinder" and disposed of in a single day.
See also 
- Genetics and the Extinction of Species, Laura F. Landweber and Andrew P. Dobson eds., Princeton University Press (1999)
- Michael Winter, USA Today, Video shows egg-industry practice of grinding up live chicks, 2009-09-01, Retrieved 2011-11-18.
- Hatcheries and the Protection of Wild Salmon
- University of Washington Libraries Digital Collections -- Digital Collections -- Fish Hatcheries An ongoing digital collection of images related to fish hatcheries.
-  - Links to hatchery reform projects