Chicken Types, Characteristics & Uses

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. In older sources, and still often in trade and scientific contexts, chickens as a species are described as common fowl or domestic fowl. Besides humans, lots of animals eat chickens as well. Modern egg-laying breeds rarely go broody and those that do often stop part-way through the incubation cycle.

• A flock thus uses only a few preferred locations, rather than having a different nest for every bird.
• 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.
• 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.

Newly hatched chicks of both modern and heritage varieties weigh the same, about 37 g (1.3 oz). While the origin is Germanic, it is unclear exactly where the word came from, although it could ultimately have come from an imitation of the sound a chicken makes. The word chicken comes from Old English cicen (pronounced essentially the same as in Modern English). Chickens are social animals with complex vocalizations and behaviors, and feature in folklore, religion, and literature across many societies.

Use by humans

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. Females (mature hens and younger chickens, called pullets) are raised for meat and for their edible eggs. The chicken is perhaps the most widely domesticated fowl, raised worldwide for its meat and eggs. These domesticated chickens spread across Southeast and South Asia where they interbred with local wild species of junglefowl, forming genetically and geographically distinct groups. Specialized breeds such as broilers and laying hens have been developed for meat and egg production, respectively.

Animal Names Glossary

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. Skeletons of birds in the Gallus genus were used as grave goods at the site, confirming domestication. 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. Fertile chicken eggs hatch at the end of the incubation period, about 21 days; the chick uses its egg tooth to break out of the shell. As with all birds, reproduction is controlled by a neuroendocrine system, the Gonadotropin-Releasing Hormone-I neurons in the hypothalamus.

Animal Classification

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. 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 khelovipbangladesh.com by different sources.