Sheep

? Sheep Conservation status: Domesticated
Romney sheep (More)
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Artiodactyla Family: Bovidae Subfamily:: Caprinae Genus: Ovis Species: O. aries
Binomial name
Ovis aries Linnaeus, 1758

Sheep, Ovis aries, are one of the first animal species domesticated by humans and have had an important part in human life for thousands of years. There are also several species of wild sheep, also members of the genus Ovis. All sheep are even-toed ungulates, hoofed mammals, and are members of the bovid, or Bovidae, family along with goats, antelopes, and cattle.

Male sheep are called rams, females ewes, and the young lambs.

Wild sheep species

Wild sheep mostly found in hilly or mountainous habitats. They are fairly small compared to other ungulates; in most species adults weigh less than 100 kg (220 lbs) (Nowak 1983). Their diet consists mainly of grasses, as well as other plants and lichens. Their bodies are covered by a coat to thick hair to protect them from the cold of their environments. The coat contains long, stiff hairs, called kemps, and a short woolly undercoat which grows in fall and is shed in spring (Clutton-Brock 1999).

Wild sheep are social animals and live in groups, most often called flocks. This helps them to avoid predators and also helps them stay warm in bad weather by huddling together. Flocks of sheep need to keep moving to find new grazing areas and more favorable climate as the seasons change. In each flock there is a sheep, usually a mature ram, which the others follow as a leader (Clutton-Brock 1999).

In wild sheep both rams and ewes have horns, with the rams' being much larger. Rams use their horns to fight with each other for dominance and for the right to mate with females. In most cases they do not injure each other because they hit each other head to head and their curved horns do not strike each other's bodies. They are also protected by having very thick skin and a double-layered skull (Voelker 1986).

There are some differences of opinion among experts on how wild sheep should be divided and named as species. One group of sheep species consists of the bighorn sheep, Ovis canadensis, and Dall sheep, O. dalli, of western North America and the closely related snow sheep, O. nivicola, of Siberia. The other group is more closely related to domestic sheep and includes the Asiatic mouflon, O. orientalis, which is thought to be the ancestor of domestic sheep. Also in this group is the urial, O. vignei, which also might have contributed to domestic sheep ancestry; as well as the argali, O. ammon. These three species are native to central and western Asia. The European mouflon, O. musimon, is found on the islands of Corsica and Sardinia in the Mediterranean Sea. It is thought to be descended from an early form of domestic sheep brought there by humans in prehistoric times (Clutton-Brock 1999, Huffman 2006, Nowak 1983).

Domestication

The process of domestication of sheep seems to have started about 10,000 years ago in southwestern Asia. It is not known how sheep came to be associated with humans. It has been suggested that humans followed wild sheep flocks killing some when they needed for meat but also protecting them from other predators. It is also possible that sheep preferred to stay near human settlements to eat crops or weeds that grew there or to lick the salt found in human urine or because predators would avoid humans. It is also possible that hunters sometimes found new-born lambs and brought them home to keep as pets (Clutton-Brock 1999).

An important factor in their domestication seems to be that sheep started to relate to humans as their flock leaders. This made it possible for a single shepherd to control a large flock of sheep. Dogs were also used to help control and protect the flocks. Because sheep can thrive in dry or hilly country that is not suited for crops the keeping of flocks gave early human communities an important additional resource. Besides meat, they provided hides which made very warm coats. Ewes began to be milked and the wool which sheep shed each spring was gathered and spun into yarn to make clothing.

Because of selective breeding, shepherds would select the sheep with the most desirable characteristics to give each year's new lambs, sheep slowly changed under domestication. They became smaller, slower, and calmer than their wild ancestors. In most breeds ewes became hornless. Some breeds arose in which the wool was not shed in spring but grew year-round.

History

Cultural significance

Australian Sheep

Sheep have had associations with many cultures, especially in the Mediterranean area and Britain, where they form the most common type of livestock in pastoralism. Selective breeding of sheep has frequently occurred and in Egyptian Mythology the ram was the symbol of Heryshaf.

A wide symbology relates to sheep in ancient art, traditions and culture. Judaism uses many sheep references including the Passover lamb. Christianity uses sheep-related images, such as: Christ as the good shepherd, or as the sacrificed Lamb of God (Agnus Dei); the bishop's Pastoral; the lion lying down with the lamb (a reference to all of creation being at peace, without suffering, predation or otherwise). Greek Easter celebrations traditionally feature a meal of Paschal lamb. Sheep also have considerable importance in Arab culture, with Eid ul-Adha being a major festival in Islam when a sheep is sacrificed yearly.

Herding sheep plays an important historico-symbolic part in the Jewish and Christian faiths, since Abraham, Jacob, Moses, and King David all worked as shepherds.

The ram is the first sign of the Western zodiac, in which it is known as Aries. The sheep (or goat) also forms one of the animals associated with the 12-year cycle of in the Chinese zodiac, related to the Chinese calendar. Chinese tradition associates each animal with certain personality traits. See: Sheep (Zodiac).

The raising of sheep for wool and meat became a major industry in colonial Australia and New Zealand and remains significant. As a result, sheep and sheep shearing have become an important part of the folklore and cultural tradition of these two countries. In New Zealand, sheep outnumber the human population 12 to 1.

Breeds

File:A sheep on a railway track.jpg

A sheep in a railway track in Mount Barker, South Australia.

There are many breeds of sheep, but these are generally sub-classable as wool class, hair class and sheep meat breeds.

Farmers develop wool breeds for superior wool quantity and quality (fineness of fibers), wool staple length and degree of crimp in the fiber. Major wool breeds include Merino, Rambouillet, Romney and Lincoln. Drysdale is a sheep bred specifically for carpet wool.

Breeds of meat sheep include Suffolk, Hampshire, Dorset, Columbia, and Texel.

Breeders of dual-purpose wool class sheep concentrate on fast growth, multiple births, ease of lambing and hardiness. An easy-care sheep is the Coopworth that has long wool and good lamb meat production qualities. Another dual-use breed is the Corriedale. Sometimes sheep are used for both purposes equally and cross-breeding is practiced to maximise both outputs. For example, Merino ewes providing wool may be crossed with Suffolk rams to produce lambs which are robust and suitable for the meat market.

Hair class sheep are the original class of sheep in the world, developed for meat and leather. They are prolific and highly resistant to disease and parasites. Dorpers and Kahtahdins are composite breeds of wool and hair crosses with different degrees of wool/hair mixes within the hair class. True hair sheep such as St. Croix, Barbados Blackbelly, Mouflon, Santa Inez and Royal White shed their protective down fiber to an all hair coat in the Spring/Summer. Hair class sheep are becoming more popular for their no-shear aspects.

Economic importance

Global Sheep and Lamb stocks in 2005
(million head)
People's Republic of China	170.9
Australia	102.7
European Union (15 nation)	99.3
former Soviet Union	65.3
India	62.5
Iran	54.0
Sudan	49.0
New Zealand	39.9
United Kingdom	35.3
South Africa	25.3
World Total	1079.0
Source: UN Food & Agriculture Organisation (FAO)[1]

Raising sheep occupied many farmers in ancient economies, given that this animal can give milk (and all its derivative products, such as cheese), wool, sheepskin (used for making footwear, rugs and other coverings) and meat. In the 21st century, sheep retain considerable importance in the economies of several countries. After China, the largest producers of sheep are in the southern hemisphere: Australia, New Zealand and the Patagonian regions of Argentina, Uruguay and Chile. Other countries may produce a very small proportion of the world market, but sheep nonetheless play an important role in their economy. In some places, like Sardinia, sheep-breeding has become the principal and characteristic activity.

In the UK, the importance of the wool trade was so significant that in the upper chamber of parliament (the House of Lords), the Lord Chancellor sits on a bench known as the Woolsack. This is, as its name suggests, a sack of wool and confers the importance of the wool trade to the English economy at the time of its installation many centuries ago.

The economic importance of sheep in much of the United States has declined as it has become, in some cases, economically unviable to ranch sheep for wool. Texas has by far the most sheep of any state, but now has only about one-tenth of the almost 11 million sheep it had in the 1940s.

Even in the 21st century, in some situations, sheep can provide a return on investment of up to 400% of their cost annually (including reproduction gains). Sheep breeding has played a role in several historic conflicts, such as the Scottish Highland Clearances, the American range wars, and the English "enclosing of the commons".

Domestication

Grazing sheep

Domestic sheep are descended from the mouflon that is found from the mountains of Turkey to southern Iran. Evidence for domestication dates to 9000 B.C.E. in Iraq. It has been found by DNA analysis to be one of two ancestors of domestic sheep. Although the second ancestor has not been identified, both the urial and argali have been ruled out. The urial (O. vignei) is found from northeastern Iran to northwestern India. It has a higher number of chromosomes (58) than domestic sheep (54) which makes it an unlikely ancestor of the latter, but it interbreeds with the mouflon. The argali sheep (O. ammon) of inner Asia (Tibet, Himalayas, Altay Mountains, Tien-Shan and Pamir) has 56 chromosomes and the Siberian snow sheep (Ovis nivicola) has 52 chromosomes.

File:Lamb with tail.jpg

Lambs are born with long tails which are cut off once they reach a certain age.

Evidence of early domesticated sheep have been found in PPNB Jericho and Zawi Chemi Shanidar. The fleece-bearing sheep are only found since the Bronze Age. Primitive breeds, like the Scottish Soay sheep have to be plucked (a process called rooing), instead of sheared, as the kemps are still longer than the soft fleece, or the fleece must be collected from the field after it falls out. The European mouflon (O. musimon) found on Corsica and Sardinia as well as the Cretan and the extinct Cypriot wild sheep are possibly descended from early domestic sheep that turned feral.

=Cuisine

Chefs and diners commonly know sheep meat prepared for food as lamb or mutton (compare the French word for "sheep": mouton).

Ewes' milk is used in the production of cheese and yogurt in many upland parts of the world. Well known sheepmilk cheeses include the Roquefort of France, the brocciu of Corsica, the pecorino of Italy and the feta cheese of Greece. Sheepmilk contains no lactose, and thus does not trigger lactose intolerance in humans. [2]

Behavior

File:Happy Sheep.jpg

Sheep graze on green pasture lands at the edge of Giants Causeway in Northern Ireland.

File:Sheep in Serbia.jpeg

A flock of sheep in Serbia

Some breeds of sheep exhibit a strong flocking behaviour. This was used as an example to Israelites in the Christian Bible to instruct them to obey their shepherd, or master. Flocking behaviour is advantageous to non-predatory animals; the strongest animals fight their way to the center of the flock which offers them great protection from predators. It can be disadvantageous when food sources are limited and sheep are almost as prone to overgrazing a pasture as goats. In Iceland, where sheep have no natural predators, and grasses grow slowly, none of the various breeds of sheep exhibit a strong flocking behaviour.

Sheep flocking behaviour is so prevalent in some English breeds that special names apply to the different roles sheep play in a flock. One calls a sheep that roams furthest away from the others an outlier, a term originally used to refer to someone who lives far from where they work. This sheep ventures further away from the safety of the flock to graze, due to a larger flight zone or a weakness that prevents it from obtaining enough forage when with the flock. Another sheep, the bellwether, leads the others. Traditionally this was a castrated ram (or wether) with a bell hung off a string around its neck. The tendency to act as an outlier, bellwether or to fight for the middle of the flock stays with sheep throughout their adulthood; that is unless they have a scary experience which causes them to increase their flight zone.

According to a spokesperson of the British National Sheep Association, "Sheep are quite intelligent creatures and have more brainpower than people are willing to give them credit for." For example, sheep in Yorkshire, England found a way to get over cattle grids by rolling on their backs. A study published in National Geographic (December 8) showed a sheep can remember the faces of fifty other sheep for over two years.

Sheep can become hefted to one particular pasture so they do not roam far from home. Since the outbreak of foot and mouth disease in the United Kingdom, transplanted sheep have had to be trained to stay in their grazing area.

References

ISBN links support NWE through referral fees

• Clutton-Brook, J. 1999. A Natural History of Domesticated Mammals. Cambridge, UK : Cambridge University Press ISBN 0521634954
• Forsyth, A. 1999. Mammals of North America. Buffalo, New York, USA : Firefly Books ISBN 155209409X
• Huffman, B. 2006. The Ultimate Ungulate Page Website [3]
• Nowak, R. M. and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0801825253
• Oklahoma State University (OSU). 2006 Breeds of Livestock: Sheep[4]
• Parker, D. 2001. The Sheep Book. Athens, Ohio, USA : Ohio University Press ISBN 0804010323
• University of California Museum of Paleontology (UCMP) 2006. "Ungulates: Hoofed Mammals"
• Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing, Inc. ISBN 0937548081

External links

• Breeds of Livestock - Sheep: (Ovis aries). Oklahoma State University. Retrieved 2006-08-02.
• Sheep at the Open Directory Project
• Genetic origins of domestic sheep
• Dutch Texel Sheep
• SHEEP 101 .info
• A Glossary of sheep terms (National Sheep Association)
• The Domestic Sheep by Henry Stewart (1898), "Natural History" and "Anatomy."

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