CHICKEN中文繁體翻譯：劍橋詞典

To initiate courting, some roosters may dance in a circle around or near a hen (a circle dance), often lowering the wing which khelovipbangladesh.com is closest to the hen. Chickens give different warning calls to indicate that a predator is approaching from the air or on the ground. Chickens are capable of mobbing and killing a weak or inexperienced predator, such as a young fox. In the wild, they scratch at the soil to search for seeds, insects, and animals as large as lizards, small snakes, and young mice. Some breeds have a mutation that causes extra feathering under the face, giving the appearance of a beard. Modern varieties however grow much faster; by day 35 a Ross 708 broiler may weigh 1.8 kg (4.0 lb) as against the 1.05 kg (2.3 lb) of a heritage chicken of the same age.

• These domesticated chickens spread across Southeast and South Asia where they interbred with local wild species of junglefowl, forming genetically and geographically distinct groups.
• Roosters can usually be differentiated from hens by their striking plumage, marked by long flowing tails and bright pointed feathers on their necks.
• Hens of some breeds can produce over 300 eggs per year; the highest authenticated rate of egg-laying is 371 eggs in 364 days.

What is a Chickens?

Middle Eastern chicken remains go back to a little earlier than 2000 BC in Syria. Chicken remains have been difficult to date, given the small and fragile bird bones; this may account for discrepancies in dates given by different sources. Chickens reached Egypt via the Middle East for purposes of cockfighting about 1400 BC and became widely bred in Egypt around 300 BC. Re-examination of bones from over 600 sites, and dating of those from 23 sites, identified the earliest probable chicken bones as from central Thailand, at Ban Non Wat, some 3,250 years ago.

What is a Chickens?

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. Eggs of chickens from the high-altitude region of Tibet have special physiological adaptations that result in a higher hatching rate in low oxygen environments.

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. Archaeological evidence appeared to support domestic chickens in Southeast Asia well before 6000 BC, China by 6000 BC and India by 2000 BC. Exactly when and where the chicken was domesticated was controversial. Inbreeding of White Leghorn chickens tends to cause inbreeding depression expressed as reduced egg number and delayed sexual maturity.

Certain breeds, such as silkies and many bantam varieties, are generally docile and are often recommended as good pets around children with disabilities. 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. Opponents of intensive farming argue that it harms the environment, creates human health risks and is inhumane towards sentient animals. Breeding increased under the Roman Empire and reduced in the Middle Ages.