Chicken

Chickens are featured widely in folklore, religion, literature, and popular culture. The chicken was the first bird species to have its genome sequenced. For instance, many important discoveries in limb development have been made using chicken embryos, such as the discovery of the apical ectodermal ridge and the zone of polarizing activity. Equally important, embryologists can carry out experiments on such embryos, close the egg again and study the effects later in development. A cockfight is a contest held in a ring called a cockpit between two cocks.

• These chickens may have been introduced during pre-Columbian times to South America via Polynesian seafarers, but this is disputed.
• The chicks imprint on the hen and subsequently follow her continually.
• The chicken was the first bird species to have its genome sequenced.
• A cockfight is a contest held in a ring called a cockpit between two cocks.
• 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.

Males (called cocks or roosters) and females (hens) are known for their fleshy combs, lobed wattles hanging below the bill, and high-arched tails. In the process of domestication, chickens were apparently kept initially for cockfighting, and only later used for food. 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.

Domestication and economic production

Females (mature hens and younger chickens, called pullets) are raised for meat and for their edible eggs. In domesticating the chicken, humans took advantage of the red junglefowl’s ability to reproduce prolifically when exposed to a surge in its food supply. The chicken (Gallus gallus domesticus) is a domesticated form of the red junglefowl (Gallus gallus), originally native to Southeast Asia. The chicken is perhaps the most widely domesticated fowl, raised worldwide for its meat and eggs.

Chickens are gregarious, living in flocks, and incubate eggs and raise young communally. The body is round, the legs are unfeathered in most breeds, and the wings are short. Chicken can mean a chick, and this was historically the meaning of the word chicken, as in William Shakespeare’s play Macbeth, where Macduff laments the death of «all my pretty chickens and their dam». As of 2023, the global chicken population exceeds 26.5 billion, with more than 50 billion birds produced annually for consumption. It was first domesticated around 8,000 years ago and is one of the most common and widespread domesticated animals in the world.

Farming

This stimulates the hen to lose her feathers but also re-invigorates egg-production. In some other countries, flocks are sometimes force-moulted rather than being slaughtered to re-invigorate egg-laying. After 12 months of laying, the commercial hen’s egg-laying ability declines to the point where the flock is commercially unviable. According to the Worldwatch Institute, 74% of the world’s poultry meat and 68% of eggs are produced this way. The parasite Dermanyssus gallinae feeds on blood, causing irritation and reducing egg production, and acts as a vector for bacterial diseases such as salmonellosis and spirochaetosis.Viral diseases include avian influenza. Genomic studies estimated that the chicken was domesticated 8,000 years ago in Southeast Asia and spread to China and India 2,000 to 3,000 years later.

Keeping chickens as pets became increasingly popular in the 2000s among urban and suburban residents. The first pictures of chickens in Europe are found on Corinthian pottery of the 7th century BC. Phoenicians spread chickens along the Mediterranean coasts as far as Iberia. These chickens may have been introduced during pre-Columbian times to South America via Polynesian seafarers, but this is disputed. Skeletons of birds in the Gallus genus were used as grave goods at the site, confirming domestication.

When eggs are placed in a hypoxic environment, chicken embryos from these populations express much more hemoglobin than embryos from other chicken populations. Under natural conditions, most birds lay only until a clutch is complete; they then incubate all the eggs. Adult chickens of both sexes have a fleshy crest on their heads called a comb or cockscomb, and hanging flaps of skin on either side under their beaks called wattles; combs and wattles are more prominent in males. In older sources, and still often in trade and scientific contexts, chickens as a species are described as common fowl or domestic fowl.

Broiler breeds typically take less than chicken road bangladesh six weeks to reach slaughter size, some weeks longer for free-range and organic broilers. Advocates of intensive farming say that their efficient systems save land and food resources owing to increased productivity, and that the animals are looked after in a controlled environment. Chickens are common and widespread domestic animals, with a total population of 23.7 billion as of 2018update. Breeding increased under the Roman Empire and reduced in the Middle Ages.