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There is considerable controversy over when and from what wild species the first domestic sheep descended. Current chromosomal and archeological evidence indicates that the divergence occurred about 9000-11000 years ago and that the first sheep domesticated were from the mounflon (Ovis musimon) flocks from Sardinia and Corsica. (Grzimek 1990)
Perception Channels: tactile ; chemical
The world population of domestic sheep has steadly increased since their domestication and the world sheep population totals over a billion sheep.
US Federal List: no special status
CITES: appendix i; no special status
Ovis aries has no adverse effects on human populations. The proliferation of domestic sheep, though, has adversely effected populations of their wild relatives through competition for forage and the spread of disease.
Ovis aries is one of the most economically significant species on the planet. Since their domestication between 9000 and 11000 years ago they have been a source of meat, milk, wool and hides in nearly every country. In some cultures sheep are considered highly useful as a sacrificial animal. The versatility of the species contributes to its economic significance as large herds of animals can be maintained in many environments at relatively low costs. Besides their usefulness in an agricultural sense, sheep have become important as a tool for scientific research. Because of their large size and low maintenance costs they make an ideal model for a great deal of scientific research.
Positive Impacts: food ; body parts are source of valuable material
Domestic sheep are extremely hardy animals and can survive on a diet consisting of only cellulose, starch or sugars as an energy source and a nitrogen source which need not be protein. In general, sheep feed mainly on grasses while in pastures and can be fed a wide variety of hays and oats. Considerable research has been done on sheep nutritional requirements, and feed substitution tables are present in Ensminger's 1965 "The Stockman's Handbook". Grazing sheep ingest a large amount of food in a short time, then retire to rest and rechew the ingested matter. Sheep spend their day alternating between these periods of grazing and ruminating. Ovis aries has a large and complex stomach which is able to digest highly fibrous foods that can not be digested by many other animals. Its modest nutritional requirements contribute to its economic significance.(Hecker 1983, Ensminger 1965)
Domestic sheep live worldwide in association with humans. The first domesticated sheep resided mainly in the Middle East and Central Asia but since then have been introduced everywhere.
Biogeographic Regions: nearctic (Introduced ); palearctic (Native ); oriental (Introduced ); ethiopian (Introduced ); neotropical (Introduced ); australian (Introduced ); oceanic islands (Introduced )
Domestic sheep are extremly versitile and exist in a wide variety of habitats worldwide ranging from temperate mountain forests to desert conditions. (Grzimek 1990, MacDonald 1984)
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral ; forest ; scrub forest ; mountains
Average lifespan
Status: captivity: 22.8 years.
The physical details of domestic sheep vary greatly among breeds. Head and body length is 1,200-1,800 mm and shoulder height is 650-1,270 mm. Female sheep tend to be three quarters to two thirds the size of males. Wild sheep have tails between 70-150 mm but in domestic sheep tails may be larger and used as a fat reserve, although these long tails are removed on most commercial farms. Sheep have a vertical cleft and narrow snout completely covered with short hair except on the margins of the nostrils and lips. The genus Ovis is characterized by the presence of glands situated in a shallow depression in the lacrimal bone, the groin area, and between the two main toes of the foot. These glands secrete a clear semi-fluid substance that gives domestic sheep their characteristic smell. The skulls of domesticated sheep differ from those of wild sheep in that the eye socket and brain case are reduced. Selection for economically important traits has produced domestic sheep with or without wool, horns, and external ears. Coloration ranges from milky white to dark brown and black. There is considerable diversity among the over 200 distinct breeds of sheep. For details on a specific breeds consult http://pc200.anmsci.okstate.edu/BREEDS/SHEEP.
Range mass: 20 to 200 kg.
Range length: 120 to 180 cm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger; ornamentation
Ovis aries breeds on a seasonal basis, determined by day length, with females (ewes) first becoming fertile in the early fall and remaining fertile through midwinter. Estrus cycles range between 14 and 20 days with 17 as the average. Females are in heat on average for 30 hours. Males (rams) are fertile year round and most domestic sheep breeders use 1 ram to 25 to 35 ewes. Gestation averages 148 days with most lambs born in mid spring. One or two lambs, which are able to stand and suckle within a few minutes of birth, are born to each ewe. Both male and female lambs reach sexual maturity within one year. (Ensminger 1965)
Range number of offspring: 1 to 2.
Average number of offspring: 1.3.
Average gestation period: 5.03 months.
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
Average birth mass: 2370 g.
Average gestation period: 146 days.
Average number of offspring: 1.58.
Average age at sexual or reproductive maturity (male)
Sex: male: 914 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 548 days.
Parental Investment: altricial
