Sheep
| Sheep Conservation status: Domesticated | ||||||||||||||||
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 Romney sheep | ||||||||||||||||
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| 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
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 of 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 population 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. Ewes began to be milked and the wool which sheep shed each spring was gathered and spun into yarn to make clothing.
Shepherds would select the sheep with the most desirable characteristics to give each year's new lambs and sheep slowly changed under domestication. They became smaller, slower, and calmer than their wild ancestors. Different breeds arose depending on different environmental conditions and standards of selection. In most breeds ewes became hornless. In some breeds which the wool was not shed in spring but grew year-round and was cut off, or shorn, usually once a year in the spring.
Wool
Sheep herding spread over much of Asia and Europe and wool became one of the most commonly used fibers for clothing and a very important product in commerce and trade. Wool has two qualities that distinguish it from hair or fur: it has scales which overlap like shingles on a roof and it is crimped; in some fleeces the wool fibers have more than 20 bends per inch. Wool's scaling and crimp make it easier to spin and felt the fleece. They help the individual fibers attach to each other so that they stay together. Because of the crimp, wool fabrics have a greater bulk than other textiles and retain air, which causes the product to retain heat. Insulation also works both ways; Bedouins and Tuaregs of the North African desert use wool clothes to keep the heat out.
The amount of crimp corresponds to the thickness of the wool fibres. A fine wool like merino may have up to a hundred crimps per inch, while the coarser wools like karakul may have as few as one to two crimps per inch. Hair, by contrast, has little if any scale and no crimp and little ability to bind into yarn. On sheep, the hair part of the fleece is called kemp. The relative amounts of kemp to wool vary from breed to breed, and make some fleeces more desirable for spinning, felting or carding into batts for quilts or other insulating products.
Wool is generally a creamy white colour, although some breeds of sheep produce natural colors such as black, brown (also called moorit) and grey.
Wool straight off a sheep contains a high level of grease which contains valuable lanolin, as well as dirt, dead skin, sweat residue, and vegetable matter. This state is known as "grease wool" or "wool in the grease". Before the wool can be used for commercial purposes it must be scoured, or cleaned. In less processed wools, vegetable matter may be removed by hand, and some of the lanolin left intact through use of gentler detergents. This semi-grease wool can be worked into yarn and knitted into particularly water-resistant mittens or sweaters, such as those of the Aran Island fishermen. Lanolin removed from wool is widely used in the cosmetics industry.
Sheep in religion
In Catal Huyuk in ancient Turkey clay heads of rams, along with heads of bulls, are found in shrines 8,000 years old (Budlansky 1992). The ancient Egyptian fertility god Heryshaf was depicted as a man with the head of a ram. In Chinese Buddhism the ram was one of the animals that attended the birth of Buddha and is honored by being one of the signs of the Chinese zodiac. The ram, Aries, is also one of the signs of the Western zodiac.
The three Abrahamic religions, Judaism, Christianity, and Islam, grew up in the sheep herding areas of the Middle East and sheep and sheep herding play important parts in all three. According to the Bible Abraham, Jacob, Moses, and King David all worked as shepherds. Abraham's sacrifice of a ram which was substituted for his son is commemorated by Muslims each year in the festival of Eid ul-Adha. Sheep are mentioned symbolically in the Bible many times, perhaps most famously in Psalm 23: "The Lord is my shepherd." In Christianity Jesus is called the Good Shepherd and the Lamb of God.
Modern sheep
There are now 200 to 300 breeds of sheep.(Voelker 1986, OSU 2003). Those bred mainly for wool 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. Hair class sheep resemble the original domesticated breeds and are useful for meat and leather. They are prolific and highly resistant to disease and parasites.
In the Twentieth Century the invention of artificial fibers took away some of the market for wool, although it is still very important and remains the most popular fiber for cold weather clothing. Sheep hides are used for coats, boots, rugs, and other products.
The production and consumption of sheep meat, called mutton if from mature sheep and lamb if from young ones, is declining in the United States but increasing in China due to improved economic conditions. In India and the Middle East religious restrictions on the eating of the meat of cattle and pigs also contribute to growing sheep meat consumption (Miller 1998).
Ewes' milk is used in the production of cheese and yogurt in many parts of the world. Well known sheep milk cheeses include the roquefort of France, the brocciu of Corsica, the pecorino of Italy and the feta cheese of Greece.
The world population of sheep in 2005 was just over one billion. China has about 170 million sheep, most of which are raised for meat. Australia, with about 100 million, and New Zealand, with about 50 million, (numbers which are many times their human population) dominate the world export trade in sheep products. Large numbers of sheep are also found in other Asian countries, Europe, Africa, and South America (Miller 1998).
ReferencesISBN links support NWE through referral fees
- Bulanskey, S. 1992. The Covenant of the Wild. New york : William Morrow and Company, Inc. ISBN 0688096107
- Clutton-Brook, J. 1999. A Natural History of Domesticated Mammals. Cambridge, UK : Cambridge University Press ISBN 0521634954
- Huffman, B. 2006. The Ultimate Ungulate Page Website [1] Retrieved January 13, 2007
- Miller, S. 1998. "Sheep and Goats". United States Department of Agriculture, Foreign Agricultural Service[2]
- 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). 2003 Breeds of Livestock: Sheep[3] Retrieved January 13, 2007
- Parker, D. 2001. The Sheep Book. Athens, Ohio, USA : Ohio University Press ISBN 0804010323
- Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing, Inc. ISBN 0937548081
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