Chickens that are raised in farms are almost never hatched by their mothers. Instead, they are hatched using artificial heat in large electric ovens called incubators, where hundreds and sometimes thousands of eggs could be hatched at the same time. Electric incubators are a modern invention, but the practice of artificial incubation itself is thousands of years old.
The Ancient Egyptians were the first to use poultry hatcheries. They fascinated foreign travellers who had never seen anything like that before. Many of these travellers left bewildering accounts of the strange method Egyptian used to get their chicks. Because they were seldom told in details the inner workings of the hatcheries, they speculated, and often got it wrong. One writer claimed that the eggs were hatched by attendants who sat on them. Friar Simon Fitzsimons, who traveled to Egypt during the 14th century, wrote in disbelief how chickens were generated by fire from eggs, “without cocks and hens,” unaware the eggs were fertilized in the traditional manner by roosters before they were placed in the incubation house. Even Aristotle wrote about the hatcheries, suggesting that they were hatched by burying the eggs in dung heaps.
The first widely read travelogue containing an authentic description of the Egyptian incubation ovens was “The Travels of Sir John Mandeville,” published in 1356. Sir Mandeville wrote:
And there is a common house in that city that is all full of small furnaces, and thither bring women of the town their eyren of hens, of geese, and or ducks for to be put into those furnaces. And they that keep that house cover them with heat of horse dung, without hen, goose or duck or any other fowl. And at the end of three weeks or of a month they come again and take their chickens and flourish them and bring them forth, so that all the country is full of them.
The French naturalist and scientist René Antoine Ferchault de Réaumur produced the first accurate description of the hatcheries in 1750. Réaumur travelled to Egypt, and visited numerous hatcheries where he watched poultry farmers work.
A typical Egyptian egg hatchery is a brick structure about nine feet high, and consist of a long, central corridor, with rooms on either side arranged in two tiers one above the other. Each floor is about the same size and is provided with an opening just large enough for a person to crawl inside. The eggs are placed on the ground floor, arranged on a bed of flax or straw. The upper rooms are used for lighting fires, using dung of cows and camels mixed with straws. This allows the fire to burn slowly in a more controlled fashion.
Fires are lighted twice a day, usually, depending on the weather, and the eggs are adequately turned about so that they are warmed on all sides equally. This continues for about two weeks, after which the fire is extinguished. At this point, the embryos’ organs are complete and the embryos are producing enough of their own internal
heat to continue the incubation process, which takes another week to complete. The eggs are finally hatched on the twenty-first day.
Back in France, Réaumur tried to build a hatchery using the Egyptian method, but because the European climate was cooler, he failed to achieve the same success as enjoyed by the Egyptian poultry farmers. After Réaumur's death, the incubator was further developed by Abbé JeanAntoine Nollet and later by Abbé Copineau, who improved Réaumur’s design by using alcohol lamps for warming the eggs. It wasn’t until the later part of the 19th century, that the first commercial incubator became available.
A traditional Egyptian hatchery using petrol lamps to warm eggs. Photo credit: Lenny Hogerwerf via Atlas Obscura
Photo credit: Lenny Hogerwerf via Atlas Obscura
In Egypt, hundreds of hatcheries are still using traditional methods developed thousands of years ago, although dung has been now replaced with petrol lamps and electric heaters. They still do not use modern equipment such as thermometers or thermostats to regulate the temperature in the hatcheries. A skilled hatchery worker can judge the temperature by holding the egg against his eyelid and letting his delicate eyeball feel the heat. If the eggs are found to be too hot, they are sprayed with water. To see if the eggs are developing, the workers simply hold the eggs up against a source of light such as a lamp. The egg shells are translucent enough to show its contents. These skills have been handed down for generations within certain families. The techniques of their profession are a closely guarded secret.
But traditional hatcheries of Egypt could soon be gone. According to a survey conducted by the Food and Agricultural Organization of the United Nations, in 2009, all hatchery owners questioned expressed desire to upgrade to modern incubation methods because of higher percentage of hatchability.
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