Chicken Types, Characteristics & Uses

The chicken is a sacred animal in many cultures and deeply embedded in belief systems and religious practices.Roosters are sometimes used for divination, a practice called alectryomancy. In 2006, scientists researching the ancestry of birds switched on a chicken recessive gene, talpid2, and found that the embryo jaws initiated formation of teeth, like those found in ancient bird fossils. In the process of domestication, chickens were apparently kept initially for cockfighting, and only later used for food.

Reproduction and life-cycle

Chicken, (Gallus gallus), any of more than 60 breeds of medium-sized poultry that are primarily descended from the wild red jungle fowl (Gallus gallus, family Phasianidae, order Galliformes) of India. 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.

• A large chicken (around 1.5kg/3lbs 5oz) will feed a family of four with leftovers for a salad or pasta dish the next day.
• Whole chickens tend to be sold trussed (tied with string) – remove this and pull the legs gently away from the body to ensure even cooking.
• Many people obtain chickens for their egg production but often name them and treat them as any other pet like cats or dogs.
• 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.
• This involves the sacrifice of a sacred rooster, often during a ritual cockfight, used as a form of communication with the gods.

Diseases

This involves complete withdrawal of food (and sometimes water) for 7–14 days or sufficiently long to cause a body weight loss of 25 to 35%, or up to 28 days under experimental conditions. Hens, particularly from battery cage systems, are sometimes infirm or have lost a significant amount of their feathers, and their life expectancy has been reduced from around seven years to less than two years. Broiler breeds typically take less than 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.

During the Hellenistic period (4th–2nd centuries BC), in the southern Levant, chickens began to be widely domesticated for food. 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. Inbreeding of White Leghorn chickens tends to cause inbreeding depression expressed as reduced egg number and delayed sexual maturity. When eggs are placed in a hypoxic environment, chicken embryos from these populations express much more hemoglobin than embryos from other chicken populations. 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. Wild junglefowl can fly, whereas domestic chickens and their flight muscles are too heavy to allow them to fly more than a short distance.

Subsequent ovulations may occur within an hour after the previous egg was laid, allowing some hens to produce as many as 300 eggs per year. Egg laying is stimulated by the long stretches of daylight that occur during the warmer months; however, artificial lights placed in chicken coops can trigger a hen’s egg laying response throughout the year. Males (called cocks or roosters) and females (hens) are known for their fleshy combs, lobed wattles hanging below the bill, and high-arched tails.

Social hierarchy

Chicken domestication likely occurred more than once in Southeast Asia and possibly India over the most recent 7,400 years, and the first domestications may have been for religious reasons or for the raising of fighting birds. In situations most play game cricket where one adult bird challenges another—which happens most often when a new bird is introduced into the flock—fights involving males risk injury and death more often than fights involving females. Each flock of chickens develops a social hierarchy that determines access to food, nesting sites, mates, and other resources. At about six months, males produce viable sperm, and females produce viable eggs.

The chicken was the first bird species to have its genome sequenced. Large numbers of embryos can be provided commercially; fertilized eggs can easily be opened and used to observe the developing embryo. Chickens are social, inquisitive, intelligent birds, and many people find their behaviour entertaining. 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.