Chicken Types, Characteristics & Uses

Domesticated chickens freely interbreed with populations of red junglefowl. Strongly inbred Langshan chickens display obvious inbreeding depression in reproduction, particularly for traits such as age when the first egg is laid and egg number. Only hens that could no longer produce enough eggs were killed and sold for meat.

• Newly hatched chicks of both modern and heritage varieties weigh the same, about 37 g (1.3 oz).
• The hen sits on the nest, fluffing up or pecking defensively if disturbed.
• Chickens are social, inquisitive, intelligent birds, and many people find their behaviour entertaining.
• As with all birds, reproduction is controlled by a neuroendocrine system, the Gonadotropin-Releasing Hormone-I neurons in the hypothalamus.
• Males (called cocks or roosters) and females (hens) are known for their fleshy combs, lobed wattles hanging below the bill, and high-arched tails.

Specialized breeds such as broilers and laying hens have been developed for meat and egg production, respectively. In the United States alone, more than 8 billion chickens are slaughtered each year for meat, and more than 300 million chickens are reared for egg production. More than 50 billion chickens are reared annually as a source of meat and eggs. An early study proposed that a single domestication event chickenroadonline-bd.com/app of the red junglefowl in present-day Thailand gave rise to the modern chicken. It is estimated that chickens share between 71 and 79% of their genome with red junglefowl.

Domestication

Fertilized embryos develop quickly, and chicks hatch approximately 21 days later. There is some debate about what the chicken’s scientific name should be. Chickens have been featured in art in farmyard scenes such as Adriaen van Utrecht’s 1646 Turkeys and Chickens and Walter Osborne’s 1885 Feeding the Chickens. The pseudo-riddle «Why did the chicken cross the road?» dates to 1847, or earlier.

Mating typically involves a sequence in which the male approaches the female and performs a waltzing display. The dance triggers a response in the hen and when she responds to his call, the rooster may mount the hen and proceed with the mating. To initiate courting, some roosters may dance in a circle around or near a hen (a circle dance), often lowering the wing which is closest to the hen. Chickens give different warning calls to indicate that a predator is approaching from the air or on the ground.

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In the UK and Europe, laying hens are then slaughtered and used in processed foods, or sold as ‘soup hens’. Hens of some breeds can produce over 300 eggs per year; the highest authenticated rate of egg-laying is 371 eggs in 364 days. During the Hellenistic period (4th–2nd centuries BC), in the southern Levant, chickens began to be widely domesticated for food. The red junglefowl is well adapted to take advantage of the vast quantities of seed produced during the end of the multi-decade bamboo seeding cycle, to boost its own reproduction. The domestic chicken has subsequently hybridised with grey junglefowl, Sri Lankan junglefowl and green junglefowl; a gene for yellow skin, for instance, was incorporated into domestic birds from the grey junglefowl (G. sonneratii).

Many people obtain chickens for their egg production but often name them and treat them as any other pet like cats or dogs. Genetic sequencing of chicken bones from archaeological sites in Europe revealed that in the High Middle Ages chickens became less aggressive and began to lay eggs earlier in the breeding season. The possibility that domestic chickens were in the Americas before Western contact is debated by researchers, but blue-egged chickens, found only in the Americas and Asia, suggest an Asian origin for early American chickens. Analysis of the most popular commercial breed shows that the White Leghorn breed possesses a mosaic of divergent ancestries inherited from different subspecies of red junglefowl.