Poultry hatcheries produce a majority of the birds consumed in the developed world including
chickens,
turkeys, ducks, geese, and some other minor bird species. A few poultry hatcheries specialize in producing birds for sale to backyard poultry keepers, hobby farmers, and people who are interested in competing with their birds at poultry shows. These hatcheries produce chicks of several different breeds and varieties, often including some heritage or endangered breeds. Larger poultry hatcheries are related to industrial poultry meat or egg production.'''''' This is a multibillion-dollar industry, with highly regimented production systems used to maximize bird size or egg production versus feed consumed. Generally large numbers are produced at one time so the resulting birds are uniform in size and can be slaughtered (for meat) or brought into production (for eggs) at the same time. A large hatchery produces 15 million chicks annually. Poultry generally start with naturally (most species) or artificially (turkeys and Cornish-related chicken breeds)
inseminated hens that lay eggs; the eggs are cleaned and shells are checked for soundness before being put into the incubators. Incubators control temperature and humidity, and turn the eggs until just before they hatch. Three days before the eggs are scheduled to hatch, they are moved into a hatcher unit, where they are no longer turned so the embryos have time to get properly oriented for their exit from the shell, and the temperature and humidity are optimum for hatching. The eggs will hatch during a period that is often referred to as the hatching window, which can stretch from 24 to 48 hours depending on biological variation. Once the eggs hatch and the chicks are a few days old, they are often vaccinated. Chicks hatched conventionally are provided feed and water first when they reach the rearing farm. In the meantime, they rely on their yolk sac for nutrients. == Turtle hatcheries ==