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:''This article refers to the sheep genus. For the species commonly referred to simply as "sheep", see [[Domestic sheep]].''
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{{taxobox
  
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{{Taxobox
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| name = Domestic sheep
  
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| status = DOM
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| name = Sheep
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| image = Flock of sheep.jpg
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| image = Ovis canadensis 2.jpg
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| image_width = 250px
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| image_width = 200px
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| image_caption = A research flock at [[U.S. Sheep Experiment Station]] near [[Dubois, Idaho]]
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| image_caption = [[Bighorn Sheep]]
 
| regnum = [[Animal]]ia
  
| regnum = [[Animal]]ia
 
| phylum = [[Chordate|Chordata]]
  
| phylum = [[Chordate|Chordata]]
 
| classis = [[Mammal]]ia
  
| classis = [[Mammal]]ia
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| ordo = [[even-toed ungulate|Artiodactyla]]
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| ordo = [[Artiodactyla]]
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| familia = [[Bovid]]ae
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| familia = [[Bovidae]]
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| subfamilia = [[goat antelope|Caprinae]]
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| subfamilia = [[Caprinae]]
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| genus = ''[[Ovis]]''
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| genus = '''''Ovis'''''
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| genus_authority = [[Carolus Linnaeus|Linnaeus]], 1758
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| species = '''''O. aries'''''
  
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| subdivision_ranks = Species
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| binomial = ''Ovis aries''
  
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| subdivision =
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| binomial_authority = [[Carolus Linnaeus|Linnaeus]], 1758
  
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See text.
 
}}
  
}}
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A '''sheep''' is an individual of any of the five or more [[mammal]] [[species]] that comprise the [[genus]] '''''Ovis''''', part of the [[goat-antelope]] [[subfamily]]. Sheep are [[bovid]]s (members of the [[scientific classification|family]] ''[[Bovidae]]'') and [[ruminant]]s, meaning they chew cud. The [[domestic sheep]] is thought to be descended from the wild [[mouflon]] of [[central Asia|central]] and [[southwest Asia]]. Members of the genus are highly gregarious.
   
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Female sheep are called ''ewes'', males are called ''rams'' (sometimes also called ''bucks'' or ''[[tup]]s'') and young sheep are called ''lambs''. The adjective applying to sheep is ''ovine'' and the collective term for sheep is ''[[Herd|flock]]'' or ''mob''. The term ''herd'' is also occasionally used in this sense. See [[Glossary of sheep husbandry]] for other terms related to domestic sheep.
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'''Domestic sheep''' (''Ovis aries'') are [[quadruped]]al, [[ruminant]] [[mammal]]s typically kept as [[livestock]]. Like all ruminants, sheep are members of the order Artiodactyla, the [[even-toed ungulate]]s. Although the name "sheep" applies to many species, in everyday usage it almost always refers to ''Ovis aries''. Numbering a little over 1 billion, domestic sheep are the most numerous species in [[Ovis|their genus]].
  
   
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Sheep are usually stockier than other bovines and some have horns which are more divergent than those of goats. Sheep have [[scent gland]]s on the face and hind feet. Communication through the scent glands is not well understood but is thought to be important for sexual signaling. Males can smell females which are fertile and ready to mate, and rams mark their territories by rubbing scent on to rocks. They have a four-chambered [[stomach]] which plays a vital role in [[digestion|digesting]], [[Regurgitation|regurgitating]], and redigesting food. Domestic sheep are important for their [[wool]], [[milk]], and [[meat]] (which is called [[Lamb (food)|mutton]] or [[Lamb (food)|lamb]]).
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Sheep are most likely descended from the wild [[mouflon]] of Europe and Asia. One of the earliest animals to be domesticated for [[agriculture|agricultural]] purposes, sheep are raised for [[Wool|fleece]], meat (lamb or mutton) and [[sheep milk|milk]]. A sheep's [[wool]] is the most widely used of any animal, and is usually harvested by [[Sheep shearing|shearing]]. [[Wikt:Ovine|Ovine]] meat is called [[Lamb and mutton|lamb]] when from younger animals and [[Lamb and mutton|mutton]] when from older ones. Sheep continue to be important for wool and meat today, and are also occasionally raised for [[Sheepskin (material)|pelts]], as [[dairy]] animals, or as [[model organism]]s for science.
  
   
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Five species and numerous subspecies of sheep are currently recognized, although some subspecies have also been considered full species. The following are the main ones:<ref>''Wilson & Reeder's Mammal species of the world'' 3rd edition [http://www.bucknell.edu/msw3/browse.asp?s=y&id=14200825 online]</ref>
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[[Sheep husbandry]] is practised throughout the majority of the inhabited world, and has been fundamental to many civilizations. In the modern era, [[Australia]], [[New Zealand]], the southern and central [[South America]]n nations, and the [[British Isles]] are most closely associated with sheep production. Sheep-raising has a large [[Glossary of sheep husbandry|lexicon of unique terms]] which vary considerably by region and [[dialect]]. Use of the word ''sheep'' began in [[Middle English]] as a derivation of the [[Old English]] word ''scēap''; it is both the singular and plural name for the animal. A group of sheep is called a flock, [[herd]] or mob. Adult female sheep are referred to as ewes, intact males as rams or tups, [[Castration|castrated]] males as wethers, and younger sheep as lambs. Many other specific terms for the various life stages of sheep exist, generally related to lambing, shearing, and age.
  
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{| class="wikitable"
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‎
  
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| [[Image:Argali.jpg|120px]] || ''Ovis ammon'' || [[Argali]]
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Being a key animal in the history of farming, sheep have a deeply entrenched place in human culture, and find representation in much modern language and [[symbology]]. As livestock, sheep are most-often associated with [[pastoral]], [[Arcadia (utopia)|Arcadian]] imagery. Sheep figure in many [[mythology|mythologies]]—such as the [[Golden Fleece]]—and major religions, especially the [[Abrahamic]] traditions. In both ancient and modern religious ritual, sheep are used as [[Animal sacrifice|sacrificial animals]]. In contemporary [[English language]] usage, people who are timid, easily led, or stupid are often compared to sheep.
  
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|-
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{{TOClimit|limit=3}}
  
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| [[Image:Ovis orientalis aries 'Skudde' (aka).jpg|120px]] || ''Ovis aries aries''<ref>ICZN ([[International Commission on Zoological Nomenclature]]) [http://www.iczn.org/BZNMar2003opinions.htm opinion 2027]</ref> || [[Domestic sheep]]
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|-
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| [[Image:Mouflon 2.jpg|120px]] || ''Ovis orientalis orientalis'' group|| [[Mouflon]]
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|-
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| [[Image:Ovis ammon vignei arkal Pretoria 3.jpg|120px]] || ''Ovis orientalis vignei'' group || [[Urial]]
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|-
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| [[Image:Ovis canadensis 2.jpg|120px]] || ''Ovis canadensis'' || [[Bighorn sheep]]
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|-
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| [[Image:2005 04 27 1582 Dall Sheep.jpg|120px]] || ''Ovis dalli'' || [[Dall Sheep]]
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|-
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| || ''Ovis nivicola'' || [[Snow sheep]]
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|}
   
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Wild sheep are 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 lb) (Nowak 1983). Their diet consists mainly of [[grass]]es, as well as other plants and [[lichens]]. Like other [[bovid]]s their [[digestive system]] enables them to digest and live on low-quality, rough plant materials. Sheep conserve water well and can live in fairly dry environments. Their bodies are covered by a coat of thick [[hair]] to protect them from cold. The coat contains long, stiff hairs, called kemps, and a short woolly undercoat, called [[fleece]], which grows in fall and is shed in spring.<ref name=Clutton-Brock>Clutton-Brock, J. 1999. ''A Natural History of Domesticated Mammals''. Cambridge, UK : Cambridge University Press ISBN 0521634954</ref>
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==Description==
 
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[[Image:Crâne mouton.jpg|thumb|A sheep's skull]]
  
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Domestic sheep are relatively small ruminants, usually with a [[Crimp (wool)|crimped]] hair called wool and often with horns forming a [[Human anatomical terms#Anatomical directions|lateral]] [[spiral]]. Domestic sheep differ from their wild relatives and ancestors in several respects, having become uniquely [[Neoteny|neotenic]] as a result of man's influence.<ref>Budiansky, pp. 97–98.</ref><ref>Budianksy, pp. 100–01.</ref> A few primitive breeds of sheep retain some of the characteristics of their wild cousins, such as short tails. Depending on breed, domestic sheep may have no horns at all (polled), or horns in both sexes (as in wild sheep), or in males only. Most horned breeds have a single pair, but a few breeds may have several.<ref name="sheep and goat"/>
 
   
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Wild sheep are social animals and live in groups, called flocks. This helps them to avoid [[predator]]s 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 <ref name=Clutton-Brock/>.
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Another trait unique to domestic sheep (as compared to wild ovines, not other livestock) are their wide variation in color. Wild sheep are largely variations of brown hues, and variation with species is extremely limited. Colors of domestic sheep range from pure white to dark chocolate brown and even spotted or [[piebald]].<ref name="rmcsba"/><ref name="bcsba"/> Selection for easily dyeable white fleeces began early in sheep domestication, and as white wool is a [[dominant trait]] it spread quickly. However, colored sheep do appear in many modern breeds, and may even appear as a [[recessive]] trait in white flocks.<ref name="bcsba">{{cite web |url=http://www.bcsba.org.uk/coloured-sheep/coloured-sheep.html |title=An introduction to coloured sheep |accessdate=2008-01-05 |publisher= British Coloured Sheep Breeders Association }}</ref><ref name="rmcsba">{{cite web |url=http://www.rmncsba.org/ |title=Natural Colored Sheep |accessdate=2008-01-05 |publisher=Rocky Mountain Natural Colored Sheep Breeders Association |month=January | year=2007 |work=Rare Breeds Watchlist }}</ref> While white wool is desirable for large commercial markets, there is a [[niche market]] for colored fleeces, mostly for [[handspinning]].<ref name="hobby"/> The nature of the fleece varies widely among the breeds, from dense and highly crimped, to long and hair-like. There is variation of wool type and quality even among members of the same flock, so [[wool classing]] is a step in the commercial processing of the fiber.
  
   
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In wild sheep both rams and ewes have [[Horn (anatomy)|horn]]s, with those of rams being much larger. The horns of a mature bighorn ram can weigh 14 kg (30 lb) &ndash; as much as the rest of its bones put together. 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.<ref name=Voelker> Voelker, W. 1986. ''The Natural History of Living Mammals''. Medford, New Jersey: Plexus Publishing, Inc. ISBN 0937548081</ref>
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[[Image:Take ours!.jpg|thumb|left|[[Suffolk sheep|Suffolks]] are a medium wool, black-faced breed of meat sheep that make up 60% of the sheep population in the U.S.<ref name="storey"/>]]
  
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Depending on breed, sheep show a range of heights and weights. Their rate of growth and mature weight is a [[heritable]] trait that is often selected for in breeding.<ref name="storey"/> Ewes typically weigh between 100 and 225&nbsp;pounds (45–100 kg), with the larger rams between 100 and 350&nbsp;pounds (45–160 kg).<ref>{{cite encyclopedia |year=2004 |author=Melinda J. Burrill Ph.D. Professor Coordinator of Graduate Studies, Department of Animal and Veterinary Sciences, California State Polytechnic University |title =Sheep |encyclopedia=World Book |publisher=Mackiev}}</ref> Mature sheep have 32 teeth ([[Dentition|dental formula]]: I:0/4 C:0/0 P:3/3 M:3/3). As with other ruminants, the eight incisors are in the lower jaw and bite against a hard, toothless pad in the upper jaw; picking off vegetation. There are no canines, instead there is a large gap between the incisors and the premolars. Until the age of four (when all the adult teeth have erupted), it is possible to see the age of sheep from their front teeth, as a pair of incisors erupts each year.
  
   
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Wild sheep have very keen [[senses]] of [[sight]] and [[Hearing (sense)|hearing]]. When detecting predators wild sheep most often flee, usually uphill to higher ground. However they can also fight back. The Dall sheep has been known to butt [[wolf|wolves]] off the face of cliffs.<ref name=Voelker/>
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The front teeth are gradually lost as sheep age, making it harder for them to feed and hindering the health and productivity of the animal. For this reason, domestic sheep on normal pasture begin to slowly decline from four years on, and the average life expectancy of a sheep is 10 to 12 years, though some sheep may live as long as 20 years.<ref name="sheep and goat">Ensminger</ref><ref>{{cite web | last =Schoenian | first =Susan | title =Sheep Basics | work =Sheep101.info | url =http://www.sheep101.info/sheepbasics.html | accessdate =2007-11-27 }}</ref><ref name="begin">Smith et al.</ref>
 
   
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==See also==
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[[Image:Ewe sheep black and white.jpg |thumb|Portrait of a Ewe Sheep in [[Scotland]]]]Sheep have good hearing, and are sensitive to noise when being handled.<ref name=smith5>Smith et al., p. 5.</ref> Sheep have horizontal slit-shaped pupils, possessing excellent [[peripheral vision]]; with visual fields of approximately 270° to 320°, sheep can see behind themselves without turning their heads.<ref name="ASI">{{cite journal |last=Shulaw |first=Dr. William P.|year=2006 |title=Sheep Care Guide |url=http://www.sheepusa.org/index.phtml?page=site/get_file&print=1&file_id=9a0f14975be048606228762fc2d2a7ff |publisher=American Sheep Industry Association|accessdate= 2008-09-08 }}</ref><ref name="hobby">Weaver</ref> However, sheep have poor [[depth perception]]; shadows and dips in the ground may cause sheep to balk. In general, sheep have a tendency to move out of the dark and into well-lit areas.<ref name="modern"/> Sheep also have an excellent sense of smell, and—like all species of their genus—have scent glands just in front of the eyes, and interdigitally on the feet. The purpose of these glands is uncertain,<ref name="Smith4"/> but those on the face may be used in breeding behaviors.<ref name="storey"/> The interdigital glands might also be used in reproduction,<ref name="storey"/> but alternative reasons, such as secretion of a waste product or a scent marker to help lost sheep find their flock, have also been proposed.<ref name="Smith4">Smith et al., p. 4.</ref>
  
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*[[Barbary Sheep]] (''Ammotragus lervia''), another type of [[goat antelope]], not closely related to ''Ovis'' sheep.
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*Blue sheep or bharal (''Pseodois''), two species of [[goat antelope]]s, not closely related to ''Ovis'' sheep.
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*[[Domestic sheep]]
   
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==References==
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Sheep and [[goat]]s are closely related (both are in the subfamily [[Caprinae]]), and it can be difficult to distinguish them by their appearance. However, they are separate species, so [[Hybrid (biology)|hybrid]]s rarely occur, and are always infertile. A hybrid of a ewe and a buck (a male goat) is called a [[sheep-goat hybrid]], and is not to be confused with the [[Chimera (genetics)|genetic chimera]] called a [[geep]]. Visual differences between sheep and goats include the beard and divided upper lip unique to goats. Sheep tails also hang down, even when short or [[Docking (animal)|docked]], while the tails of goats are held upwards. Sheep breeds are also often naturally [[polled]] (either in both sexes or just in the female), while naturally polled goats are rare (though many are polled artificially). Males of the two species differ in that buck goats acquire a unique and strong odor during the [[Rut (mammalian reproduction)|rut]], whereas rams do not.<ref name="begin"/>
 
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Because of their economic importance and ease of access most psychological orientated resarch on sheep has been conducted on the [[domestic sheep]] so the majority of references are in that article.
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{{Reflist}}
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*Bulanskey, S. 1992. ''The Covenant of the Wild''. New York: William Morrow and Company, Inc. ISBN 0688096107
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*Ciuti, S., Pipia, A., Ghiandai, F., Grignolio, S., & Apollonio, M. (2008). The key role of lamb presence in affecting flight response in Sardinian mouflon (Ovis orientalis musimon): Behavioural Processes Vol 77(3) Mar 2008, 408-412.
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*Green, D. J. (2005). Review of Soay Sheep: Dynamics and Selection in an Island Population: Applied Animal Behaviour Science Vol 93(1-2) Sep 2005, 179-180.
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*Mooring, M. S., Hart, B. L., Fitzpatrick, T. A., Reisig, D. D., Nishihira, T. T., Fraser, I. C., et al. (2006). Grooming in desert bighorn sheep (Ovis Canadensis Mexicana) and the ghost of parasites past: Behavioral Ecology Vol 17(3) May-Jun 2006, 364-371.
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*Langbein, J., Streich, J., & Scheibe, K. M. (1998). Characteristic activity patterns of female mouflons (Ovis orientalis musimon) in the lambing period: Applied Animal Behaviour Science Vol 58(3-4) Jul 1998, 281-292.
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*Loehr, J., Carey, J., Ylonen, H., & Suhonen, J. (2008). Coat darkness is associated with social dominance and mating behaviour in a mountain sheep hybrid lineage: Animal Behaviour Vol 76(5) Nov 2008, 1545-1553.
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*Nowak, R. M. and J. L. Paradiso. 1983. ''Walker's Mammals of the World''. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0801825253
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*Parker, D. 2001. ''The Sheep Book''. Athens, Ohio, USA : Ohio University Press ISBN 0804010323
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*Perez-Barberia, F. J., Walker, D. M., & Marion, G. (2007). Maximizing intake under challenging foraging conditions at two spatial scales in Soay sheep: Animal Behaviour Vol 73(2) Feb 2007, 339-348.
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*Toomer, E. E. (1997). The ethological characteristics and habitat of the desert bighorn sheep. Dissertation Abstracts International: Section B: The Sciences and Engineering.
   
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===Breeds===
  
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[[Image:Synchronized Sheep Judging.jpg|thumb|Sheep being judged for adherence to their [[breed standard]], and being held by the most common method of restraint]]
  
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{{seealso|List of sheep breeds}}
  
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The domestic sheep is a multi-purpose animal, and the more than 200 [[List of sheep breeds|breeds]] now in existence were created to serve these diverse purposes.<ref name="okstate">{{cite web |url=http://www.ansi.okstate.edu/breeds/sheep/ |title=Sheep (Ovis aries) |accessdate= 2007-11-02 |work=Breeds of Livestock |publisher=Oklahoma State University Dept. of Animal Science }}</ref><ref name="sheep and goat"/> Some sources give a count of a thousand or more breeds, but these numbers cannot be verified.<ref name="hobby"/><ref name="begin"/> Almost all sheep are classified as being best suited to furnishing a certain product: wool, meat, milk, hides, or a combination in a dual-purpose breed. Other features used when classifying sheep include face color (generally white or black), tail length, presence or lack of horns, and the [[topography]] for which the breed has been developed. This last point is especially stressed in the UK, where breeds are described as either upland (hill or mountain) or lowland breeds.<ref name="modern">{{cite book |title=The Modern Shepherd |last=Brown |first=Dave |coauthors= Sam Meadowcroft |year=1996 |publisher=Farming Press |location=Wharfedale Road, Ipswich 1P1 4LG, United Kingdom |isbn=0-85236-188-2 }}</ref> A sheep may also be of a [[fat-tailed sheep|fat-tailed breed]], which is a dual-purpose sheep common in Africa and Asia with larger deposits of fat within its tail.
  
   
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Breeds are also grouped based on how well they are suited to producing a certain type of breeding stock. Generally, sheep are thought to be either "ewe breeds" or "ram breeds". Ewe breeds are those that are hardy, and have good reproductive and mothering capabilities—they are for replacing breeding ewes in standing flocks. Ram breeds are selected for rapid growth and carcase quality, and are mated with ewe breeds to produce meat lambs. Lowland and upland breeds are also crossed in this fashion, with the hardy hill ewes crossed with larger, fast-growing lowland rams to produce ewes called [[Mule (sheep)|mules]], which can then be crossed with meat-type rams to produce prime market lambs.<ref name="modern"/> Many breeds, especially rare or primitive ones, fall into no clear category.
  
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[[Image:Barbados Blackbelly.JPG|thumb|left|upright|The [[Barbados Blackbelly]] is a hair sheep breed of [[Caribbean]] origin.]]
  
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Breeds are categorized by the type of their wool. Fine wool breeds are those that have wool of great crimp and density, which are preferred for textiles. Most of these were derived from [[Merino (sheep)|Merino]] sheep, and the breed continues to dominate the world sheep industry. Downs breeds have wool between the extremes, and are typically fast-growing meat and ram breeds with dark faces.<ref name="D’Arcy">D’Arcy, J.B., Sheep Management & Wool Technology, NSW University Press, 1986, ISBN 0 86840 106 4</ref> Some major medium wool breeds, such as the [[Corriedale sheep|Corriedale]], are dual-purpose crosses of long and fine-wooled breeds and were created for high-production commercial flocks. Long wool breeds are the largest of sheep, with long wool and a slow rate of growth. Long wool sheep are most valued for crossbreeding to improve the attributes of other sheep types. For example: the American [[Columbia (sheep)|Columbia]] breed was developed by crossing [[Lincoln (sheep)|Lincoln]] rams (a long wool breed) with fine-wooled [[Rambouillet (sheep)|Rambouillet]] ewes.
  
   
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Coarse or [[carpet]] wool sheep are those with a medium to long length wool of characteristic coarseness. Breeds traditionally used for carpet wool show great variability, but the chief requirement is a wool that will not break down under heavy use (as would that of the finer breeds). As the demand for carpet-quality wool declines, some breeders of this type of sheep are attempting to use a few of these traditional breeds for alternative purposes. Others have always been primarily meat-class sheep.<ref name="living"/>
  
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A minor class of sheep are the [[dairy]] breeds. Dual-purpose breeds that may primarily be meat or wool sheep are often used secondarily as milking animals, but there are a few breeds that are predominantly used for milking. These sheep do produce a higher quantity of milk and have slightly longer lactation curves.<ref>{{cite book |title=Dairy Sheep Nutrition |last=Pulina |first=Giuseppe |coauthors=Roberta Bencini |year=2004 |publisher=CABI Publishing |isbn=0851995950 |url=http://books.google.com/books?id=rTdfR3UxWXQC&dq=dairy+sheep+breeds}}</ref> In the quality of their milk, fat and protein content percentages of dairy sheep vary from non-dairy breeds but lactose content does not.<ref name="Pulina2">Pulina et al p. 2.</ref>
  
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A last group of sheep breeds is that of fur or hair sheep, which do not grow wool at all. Hair sheep are similar to the early domesticated sheep kept before woolly breeds were developed, and are raised for meat and pelts. Some modern breeds of hair sheep, such as the [[Dorper (sheep)|Dorper]], result from crosses between wool and hair breeds. For meat and hide producers, hair sheep are cheaper to keep, as they do not need shearing.<ref name="living"/> Hair sheep are also more resistant to parasites and hot weather.<ref name="begin"/>
  
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With the modern rise of corporate [[agribusiness]] and the decline of localized [[family farm]]s, many breeds of sheep are in danger of extinction. The [[Rare Breeds Survival Trust]] of the UK lists 22 native breeds as having only 3,000 registered animals (each), and the [[American Livestock Breeds Conservancy]] lists 14 as having fewer than 10,000.<ref>{{cite web |url=http://www.rbst.org.uk/watch-list/sheep.php |title=Sheep |accessdate=2008-09-07 |author=[[Rare Breeds Survival Trust]] (UK) |month=January | year=2008 |work=Rare Breeds Watchlist }}</ref><ref>{{cite web |url=http://www.rbst.org.uk/watch-list/main.php|title=Watchlist |accessdate=2008-09-07 |author=[[Rare Breeds Survival Trust]] (UK) |month= | year=2008 |work=A numerical guide to the 2008 Watchlist categories }}</ref><ref>{{cite web |url=http://www.albc-usa.org/cpl/wtchlist.html#sheep |title=Conservation Priority List |accessdate=2008-01-02 |author=[[American Livestock Breeds Conservancy]] |year=2007 }}</ref> Preferences for breeds with uniform characteristics and fast growth have pushed heritage (or heirloom) breeds to the margins of the sheep industry.<ref name="living"/> Those that remain are maintained through the efforts of conservation organizations, breed registries, and individual farmers dedicated to their preservation.
  
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==Diet==
  
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[[Image:German ewe grazing closeup.jpg|thumb|upright|A ewe grazing]]
  
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Sheep are exclusively [[herbivorous]] mammals. Like all ruminants, sheep have a complex [[digestive system]] composed of four chambers, allowing them to break down [[cellulose]] from stems, leaves, and seed hulls into simpler [[carbohydrate]]s. When sheep graze, vegetation is chewed into a mass called a [[Bolus (digestion)|bolus]], which is then passed into the first chamber: the [[rumen]]. The rumen is a 5- to 10-gallon (19–38&nbsp;l) organ in which feed is [[Fermentation (food)|fermented]] via a [[symbiotic]] relationship with the [[bacteria]], [[protozoa]], and [[yeast]]s of the [[gut flora]].<ref name=simmons146>Simmons & Ekarius, p. 146.</ref> The bolus is periodically regurgitated back to the mouth as [[cud]] for additional chewing and [[salivation]].<ref name=simmons146/> Cud chewing is an [[adaptation]] allowing ruminants to graze more quickly in the morning, and then fully chew and digest feed later in the day.<ref>Smith et al., p. 56.</ref> This is beneficial as grazing, which requires lowering the head, leaves sheep vulnerable to predators, while cud chewing does not.<ref name="begin"/>
  
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During fermentation, the rumen produces gas that must be expelled; disturbances of the organ, such as sudden changes in a sheep's diet, can cause potentially fatal conditions such as [[bloat]]. After fermentation in the rumen, feed passes in to the [[Reticulum (anatomy)|reticulum]] and the [[omasum]]; special feeds such as grains may bypass the rumen altogether. After the first three chambers, food moves in to the [[abomasum]] for final digestion before processing by the [[intestine]]s. The abomasum is the only one of the four chambers analogous to the human stomach (being the only one that absorbs nutrients for use as energy), and is sometimes called the "true stomach".<ref>Simmons & Ekarius, p. 171.</ref>
  
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Sheep follow a [[diurnality|diurnal]] pattern of activity, feeding from dawn to dusk, stopping sporadically to rest and chew their [[cud]]. Ideal pasture for sheep is not lawn-like grass, but an array of [[grass]]es, [[legume]]s and [[forb]]s.<ref>Simmons & Ekarius, p. 82.</ref> Types of land where sheep are raised vary widely, from pastures that are seeded and improved intentionally to rough, native lands. Common plants toxic to sheep are present in most of the world, and include (but are not limited to) oak and acorns, tomato, [[Taxus|yew]], rhubarb, potato, and [[rhododendron]].<ref>Simmons & Ekarius, p. 160.</ref>
  
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[[Image:Rumen-sheep2.jpg|thumb|left|A sheep's ruminant system]]
  
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Sheep are largely [[grazing]] herbivores, unlike [[Browsing (predation)|browsing]] animals such as goats and deer that prefer taller foliage. With a much narrower face, sheep crop plants very close to the ground and can [[overgraze]] a pasture much faster than cattle.<ref name="begin"/> For this reason, many shepherds use [[managed intensive rotational grazing]], where a flock is rotated through multiple pastures, giving plants time to recover.<ref name="begin"/><ref name="modern"/> Paradoxically, sheep can both cause and solve the spread of [[invasive species|invasive plant species]]. By disturbing the natural state of pasture, sheep and other livestock can pave the way for invasive plants. However, sheep also prefer to eat invasives such as [[cheatgrass]], [[leafy spurge]], [[kudzu]] and [[spotted knapweed]] over native species such as [[sagebrush]], making grazing sheep effective for [[conservation grazing]].<ref>Simmons & Ekarius, p. 143.</ref> Research conducted in [[Imperial County, California]] compared lamb grazing with [[herbicides]] for [[weed]] control in seedling [[alfalfa]] fields. Three trials demonstrated that grazing lambs were just as effective as herbicides in controlling winter weeds. [[Entomologist]]s also compared grazing lambs to [[insecticides]] for insect control in winter alfalfa. In this trial, lambs provided insect control as effectively as insecticides.<ref>{{cite web |url=http://ucanr.org/delivers/impactview.cfm?impactnum=176 |title=Sheep grazing reduces pesticide use in alfalfa |work=ucanr.org |publisher=University of California Agriculture and Natural Resources }}</ref>
  
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Other than forage, the other staple feed for sheep is [[hay]], often during the winter months. The ability to thrive solely on pasture (even without hay) varies with breed, but all sheep can survive on this diet.<ref name="living"/> Also included in some sheep's diets are [[mineral]]s, either in a trace mix or in [[Salt lick|licks]].
  
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Naturally, a constant source of [[potable]] water is also a fundamental requirement for sheep. The amount of water needed by sheep fluctuates with the season and the type and quality of the food they consume.<ref name=wooster64>Wooster, p. 64.</ref> When sheep feed on large amounts of new growth and there is [[precipitation (meteorology)|precipitation]] (including [[dew]], as sheep are dawn feeders), sheep need less water. When sheep are confined or are eating large amounts of cured [[hay]], more water is typically needed. Sheep also require clean water, and may refuse to drink water that is covered in [[Wiktionary:scum|scum]] or [[algae]].<ref name=wooster64/>
  
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Sheep are one of the few livestock animals raised for meat today that have never been widely raised in an [[Intensive farming|intensive]], [[confined animal feeding operation]] (CAFO).<ref name="hobby"/> Although there is a growing movement advocating alternative farming styles, a large percentage of [[beef]] cattle, [[pig]]s, and [[poultry]] are still produced under such conditions.<ref name="storey"/> In contrast, only some sheep are regularly given high-concentration grain feed, much less kept in confinement. Especially in industrialized countries, sheep producers may fatten market lambs before slaughter (called "finishing") in [[feedlot]]s.<ref name="begin"/> Many sheep breeders [[Glossary of sheep husbandry|flush]] ewes and rams with a daily ration of grain during breeding to increase [[fertility]].<ref>Smith et al., p. 101.</ref> Ewes are also flushed during pregnancy to increase birth weights, as 70% of a lamb's growth occurs in the last five to six weeks of gestation.<ref name="hobby"/> Otherwise, only lactating ewes and especially old or infirm sheep are commonly provided with grain.<ref name="hobby"/><ref name="living"/> Feed provided to sheep must be specially formulated, as most cattle, poultry, pig, and even some goat feeds contain levels of [[copper]] that are lethal to sheep.<ref name="hobby"/> The same danger applies to mineral supplements such as [[salt lick]]s.<ref>Simmons & Ekarius, p. 159.</ref>
  
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==Behavior and intelligence==
  
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[[Image:Border Collie sheepdog trial.jpg|thumb|250px|Sheep showing flocking behavior during a [[sheepdog trial]]]]
  
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Sheep are [[Predation|prey]] animals with a strong gregarious instinct, and a majority of sheep behaviors can be understood in these terms. The [[dominance hierarchy]] of ''Ovis aries'' and its natural inclination to follow a leader to new pastures were the pivotal factors in it being one of the first domesticated livestock species.<ref name="wild">Budiansky</ref> All sheep have a tendency to congregate close to other members of a flock, although this behavior varies with breed.<ref name=smith5/> Farmers exploit this behavior to keep sheep together on unfenced pastures and to move them more easily. Shepherds may also use [[sheepdog]]s in this effort, whose highly bred [[herding]] ability can assist in moving flocks. Sheep are also extremely food-oriented, and association of humans with regular feeding often results in sheep soliciting people for food.<ref>Budiasnky p. 100 et al.</ref> Those who are moving sheep may exploit this behavior by leading sheep with buckets of feed, rather than forcing their movements with herding.<ref>Budiansky p. 100.</ref><ref>Wooster pp. 73, 75.</ref>
  
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In regions where sheep have no natural predators, none of the native breeds of sheep exhibit a strong flocking behavior.<ref name="begin"/> Sheep can also become [[hefted]] to one particular local pasture (heft) so they do not roam freely in unfenced landscapes. Ewes teach the heft to their lambs, and if whole flocks are culled it must be retaught to the replacement animals.<ref>{{cite web| url=http://news.bbc.co.uk/1/hi/england/1634526.stm| publisher=[[BBC News]]| date=[[2001-11-03]]| title=Sheep taught to stay put| accessdate=2006-04-29}}</ref><ref name="storey"/>
  
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[[Image:Round 'em up.jpg|thumb|left|Escaped sheep being led back to pasture with the enticement of food. This method of moving sheep works best with smaller flocks.]]
  
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Flock dynamics in sheep are, as a rule, only exhibited in a group of four or more sheep. Fewer sheep may not react as normally expected when alone or with few other sheep.<ref name="hobby"/> For sheep, the primary defense mechanism is simply to flee from danger when their [[flight zone]] is crossed. Secondly, cornered sheep may charge or threaten to do so through hoof stamping and aggressive posture. This is particularly true for ewes with newborn lambs.<ref name="hobby"/>
  
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In displaying flocking, sheep have a strong lead-follow tendency, and a leader often as not is simply the first sheep to move. However, sheep do establish a [[pecking order]] through physical displays of dominance. Dominant animals are inclined to be more aggressive with other sheep, and usually feed first at [[wiktionary:trough|trough]]s.<ref>Simmons & Ekarius, p. 8.</ref> Primarily among rams, horn size is a factor in the flock hierarchy.<ref name="Budiansky78">Budiansky p. 78.</ref> Rams with different size horns may be less inclined to fight to establish pecking order, while rams with similarly sized horns are more so.<ref name="Budiansky78"/>
  
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Sheep can become stressed when separated from their flock members.<ref name="storey"/> Sheep can recognize individual human and ovine faces, and remember them for years.<ref name="nature">{{cite journal |last=Kendrick |first=Keith |coauthors=da Costa AP, Leigh AE, Hinton MR, Peirce JW |year=2001 |month=November |title=Sheep don't forget a face |journal=Nature |volume= 414|issue= |pages= 165|id=11700543 |url=http://www.ncbi.nlm.nih.gov/sites/entrez?db=pubmed&uid=11700543&cmd=showdetailview&indexed=google |doi=10.1038/35102669 }}</ref><ref name="minds">{{Cite journal|last=Morell|first=Virginia|month=March | year=2008|title=Animal Minds|periodical=[[National Geographic Magazine]]|publisher=The [[National Geographic Society]]|volume=213|issue=3}} pg. 47</ref> Relationships in flocks tend to be closest among related sheep: in mixed-breed flocks same-breed subgroups tend to form, and a ewe and her direct descendants often move as a unit within large flocks.<ref name="hobby"/>
  
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Sheep are frequently thought of as extremely unintelligent animals.<ref>Smith et al., p. 3.</ref> A sheep's [[herd mentality]] and quickness to flee and panic in the face of stress often make shepherding a difficult endeavor for the uninitiated. Despite these perceptions, a [[University of Illinois system|University of Illinois]] [[monograph]] on sheep found them to be just below pigs and on par with cattle in [[Intelligence quotient|IQ]],<ref name="hobby"/> and some sheep have shown problem-solving abilities; a flock in [[West Yorkshire]], [[England]] allegedly found a way to get over [[cattle grid]]s by rolling on their backs, although documentation of this has relied on anecdotal accounts.<ref>{{cite news|url=http://www.guardian.co.uk/uk/2004/jul/30/sillyseason.ruralaffairs|title=Pennine spot where sheep won't be fenced in|last=Wainwright|first=Martin|date=2004-07-30|work=[[The Guardian]]|accessdate=2008-06-17}}</ref> In addition to long-term facial recognition of individuals, sheep can also differentiate emotional states through facial characteristics.<ref name="nature"/><ref name="minds"/> If worked with patiently, sheep may learn their names, and many sheep are trained to be led by [[halter]] for showing and other purposes.<ref name="hobby"/> Sheep have also responded well to [[clicker training]].<ref name="hobby"/> Very rarely, sheep are used as pack animals. [[Tibetan people|Tibetan]] nomads distribute baggage equally throughout a flock as it is herded between living sites.<ref name="hobby"/>
  
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==Reproduction==
  
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{{main|Domestic sheep reproduction}}
  
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[[Image:Emerging lamb cropped.jpg|thumb|The second of twins being born on a New Zealand pasture]]
  
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Sheep follow a similar [[Reproduction|reproductive]] strategy to other herd animals. A group of ewes is generally mated by a single ram, who has either been chosen by a breeder or has established dominance through physical contest with other rams (in [[feral]] populations).<ref name="living"/> Most sheep are seasonal breeders, although some are able to breed year-round.<ref name="living"/> Ewes generally reach sexual maturity at six to eight months of age, and rams generally at four to six months.<ref name="living"/> Ewes have [[estrus]] cycles about every 17 days,<ref>Wooster, p. 111.</ref> during which they emit a scent and indicate readiness through physical displays towards rams. A minority of sheep display a preference for [[homosexuality]] (8% on average)<ref name="nyt"/> or are [[freemartin]]s (female animals that are behaviorally masculine and lack functioning [[Ovary|ovaries]]).<ref name="freemartin">{{cite journal |last=Padula |first=A.M. |year=2005 |title=The freemartin syndrome: an update. |journal=Animal Reproduction Science |volume= 87|issue= 1/2 |pages=pp. 93–109 |url=http://www.cababstractsplus.org/google/abstract.asp?AcNo=20053098181 |doi=10.1016/j.anireprosci.2004.09.008}}</ref>
  
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Without human intervention, rams fight during the [[Rut (mammalian reproduction)|rut]] to determine which individuals may mate with ewes. Rams, especially unfamiliar ones, will also fight outside the breeding period to establish dominance; rams can kill one another if allowed to mix freely.<ref name="living"/> During the rut, even normally friendly rams may become aggressive towards humans due to increases in their hormone levels.<ref name="storey"/>
  
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After mating, sheep have a [[gestation]] period of about five months,<ref>Wooster, p. 71.</ref> and normal labor may take one to three hours.<ref>Wooster, p. 124.</ref> Although some breeds may regularly throw larger litters of lambs, most produce single or twin lambs.<ref name="storey"/><ref name="quints">{{cite news |title=Quintuplet birth takes sheep breeder by surprise |url=http://www.praguemonitor.com/en/258/czech_business/17581/ |work=Prague Daily Monitor |publisher=Czech News Agency |date= 2008-01-24 |accessdate=2008-01-25 }}</ref> During or soon after labor, ewes and lambs may be confined to small [[Glossary of sheep husbandry|lambing jugs]],<ref>Smith, et al., p. 32.</ref> small pens designed to aid both careful observation of ewes and to cement the bond between them and their lambs.<ref name="living"/><ref name="modern"/> [[Image:Lamb first steps (edited).jpg|thumb|left|A lamb's first steps]]
  
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Ovine [[obstetrics]] can be problematic. By selectively breeding ewes that produce multiple offspring with higher birth weights for generations, sheep producers have inadvertently caused some domestic sheep to have difficulty lambing; balancing ease of lambing with high productivity is one of the dilemmas of sheep breeding.<ref>Budiansky, pp. 122–23.</ref> In the case of any such problems, those present at lambing may assist the ewe by extracting or repositioning lambs.<ref name="living"/> After the birth, ewes ideally break the [[amniotic sac]] (if it is not broken during labor), and begin licking clean the lamb.<ref name="living"/> Most lambs will begin standing within an hour of birth.<ref name="living"/> In normal situations, lambs nurse after standing, receiving vital [[colostrum]] milk. Lambs that either fail to nurse or that are rejected by the ewe require aid to live, such as bottle-feeding or fostering by another ewe.<ref>Smith et al., p. 110.</ref>
  
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After lambs are several weeks old, [[Glossary of sheep husbandry|lamb marking]]—the process of [[Glossary of sheep husbandry|ear tagging]], [[Docking (animal)|docking]], and [[castrating]]—is carried out.<ref name="living"/> Vaccinations are usually carried out at this point as well. Ear tags with numbers are attached, or ear marks are applied for ease of later identification of sheep. Castration is performed on ram lambs not intended for breeding, although some shepherds choose to avoid the procedure for ethical, economic or practical reasons.<ref name="living"/> Ram lambs that will either be slaughtered or separated from ewes before sexual maturity are not usually castrated.<ref name="modern"/> Docking, which is the shortening of a lamb's tail, is practised for health reasons.<ref>Smith, et al., p. 112.</ref> Objections to all these procedures have been raised by animal rights groups, but farmers defend them by saying they solve many practical and veterinary problems, and inflict only temporary pain.<ref name="storey"/><ref name="living"/>
  
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==Health==
  
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[[Image:Scrapie testing.jpg‎|thumb|upright|A veterinarian draws blood to test for resistance to scrapie]]
  
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Sheep may fall victim to poisons, infectious diseases, and physical injuries. As a prey species, a sheep's system is adapted to hide the obvious signs of illness, to prevent being targeted by predators.<ref name="storey"/> However, there are some obvious signs of ill health, with sick sheep eating little, vocalizing excessively, and being generally listless.<ref>Wooster, p. 187.</ref> Throughout history, much of the money and labor of sheep husbandry has aimed to prevent sheep ailments. Historically, shepherds often created remedies by experimentation on the farm. In some developed countries, including the United States, sheep lack the economic importance for drugs companies to perform expensive clinical trials required to approve drugs for ovine use.<ref>Smith et al., p. 95.</ref> In such instances, shepherds resort to illegal, extra-label usage of drugs approved for other animals.<ref name="storey"/> In the 20th and 21st centuries, a minority of sheep owners have turned to alternative treatments such as [[homeopathy]], [[herbalism]] and even [[traditional Chinese medicine]] to treat sheep veterinary problems.<ref name="storey"/><ref name="hobby"/> Despite some favorable [[anecdotal evidence]], the effectiveness of alternative veterinary medicine has been met with skepticism in [[scientific journal]]s.<ref name="storey"/><ref name="hobby"/><ref>{{cite journal|author=Paolo Bellavite, Riccardo Ortolani, and Anita Conforti |year=2006 |month=June |title=Immunology and Homeopathy. Experimental Studies on Animal Models |journal=Evidence Based Complementary Alternative Medicine |volume=3 |issue=2 |pages=pp. 171–86 |url=http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1475939|accessdate=2008-02-12|pmid=16786046|doi=10.1093/ecam/nel016}}</ref> The need for traditional anti-parasite drugs and [[antibiotic]]s is widespread, and is the main impediment to certified [[organic farming]] with sheep.<ref name="living">Wooster</ref>
  
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Many breeders take a variety of [[Preventive medicine|preventative measures]] to ward off problems. The first is to ensure that all sheep are healthy when purchased. Many buyers avoid outlets known to be clearing houses for animals culled from healthy flocks as either sick or simply inferior.<ref name="storey"/> This can also mean maintaining a closed flock, and [[Quarantine|quarantining]] new sheep for a month. Two fundamental preventative programs are maintaining good nutrition and reducing stress in the sheep. Handling sheep in loud, erratic ways causes them to produce [[cortisol]], a [[stress hormone]]. This can lead to a weakened [[immune system]], thus making sheep far more vulnerable to disease.<ref name="hobby"/> Signs of stress in sheep include: excessive [[panting]], [[teeth grinding]], restless movement, wool eating, and wood chewing.<ref name="hobby"/> Avoiding poisoning is also important, common poisons are [[pesticide]] sprays, inorganic [[fertilizer]], [[motor oil]], as well as radiator [[coolant]] (the [[ethylene glycol]] [[antifreeze]] is sweet-tasting).<ref>Simmons & Ekarius, p. 161.</ref> [[Image:Sheep with orf.jpg|thumb|left|A sheep infected with Orf, a disease transmittable to humans through skin contact]]
  
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Common forms of preventive medication for sheep are [[vaccination]]s and treatments for [[parasites]]. Both external and internal parasites are the most prevalent malady in sheep, and are either fatal, or reduce the productivity of flocks.<ref name="storey"/> [[Worm]]s are the most common internal parasites. They are ingested during grazing, incubate within the sheep, and are expelled through the digestive system (beginning the cycle again). Oral anti-parasitic medicines known as [[drench]]es are given to a flock to treat worms, sometimes after worm eggs in the feces has been counted to assess infestation levels. Afterwards, sheep may be moved to a new pasture to avoid ingesting the same parasites.<ref name="modern"/> External sheep parasites include: lice (for different parts of the body), sheep [[Hippoboscidae|ked]]s, [[nose bot]]s, [[Psorergates ovis|sheep itch mite]], and [[maggot]]s. Keds are blood-sucking parasites that cause general malnutrition and decreased productivity, but are not fatal. Maggots are those of the [[bot fly]] and the [[blow-fly]]. Fly maggots cause the extremely destructive condition of [[flystrike]]. Flies lay their eggs in wounds or wet, manure-soiled wool, when the maggots hatch they burrow into a sheep's flesh, eventually causing death if untreated. In addition to other treatments, [[crutching]] (shearing wool from a sheep's rump) is a common preventative method. Nose bots are flies that inhabit a sheep's [[Paranasal sinus|sinuses]], causing breathing difficulties and discomfort. Common signs are a discharge from the nasal passage, sneezing, and frantic movement such as head shaking. External parasites may be controlled through the use of [[Glossary of sheep husbandry|backliner]]s, sprays or immersive [[sheep dip]]s.<ref name="storey"/>
  
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A wide array of bacterial diseases affect sheep. Diseases of the hoof, such as [[foot rot]] and foot scald may occur, and are treated with footbaths and other remedies. These painful conditions cause lameness and hinder feeding. Ovine [[Johne's disease]] is a wasting disease that affects young sheep. [[Bluetongue disease]] is an insect-borne illness causing fever and inflammation of the [[mucous membrane]]s. [[Ovine rinderpest]] (or ''peste des petits ruminants'') is a highly contagious and often fatal [[viral]] disease affecting sheep and goats.
 
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A few sheep conditions are transmittable to humans. [[Orf (animal disease)|Orf]] (also known as scabby mouth, contagious ecthyma or soremouth) is a skin disease leaving lesions that is transmitted through skin-to-skin contact. More seriously, the organisms that can cause spontaneous enzootic [[abortion]] in sheep are easily transmitted to pregnant women. Also of concern are the [[prion]] disease [[scrapie]] and the [[virus]] that causes [[foot-and-mouth disease]] (FMD), as both can decimate entire flocks. The latter poses a slight risk to humans. During the 2001 FMD pandemic in the UK, hundreds of sheep were culled and some rare British breeds were at risk of extinction due to this.<ref name="storey"/>
 
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===Predation===
  
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{{main|Domestic sheep predation}}
  
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[[Image:Coyotekilling.jpg|thumb|A lamb being attacked by coyotes with the most typical method, a bite to the throat]]
  
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Other than parasites and disease, [[predation]] is a threat to sheep and the profitability of sheep raising. Sheep have little ability to defend themselves, compared with other species kept as livestock. Even if sheep survive an attack, they may die from their injuries, or simply from panic.<ref name="storey"/> However, the impact of predation varies dramatically with region. In Africa, Australia, the Americas, and parts of Europe and Asia predators are a serious problem. In the United States, for instance, over 1/3 of sheep deaths in 2004 were caused by predation.<ref name="nass"/> In contrast, other nations are virtually devoid of sheep predators, particularly islands known for extensive sheep husbandry.<ref name="storey"/> Worldwide, [[Canidae|canid]]s—including the domestic dog—are responsible for most sheep deaths.<ref>{{cite news |title=Sheep mauled by wild dogs |url=http://www.tweednews.com.au/?storyid=3761352&thesection=localnews&thesubsection=&thesecondsubsection= |work=Tweed Daily News |date= 2008-01-18 |accessdate=2008-01-21 }}</ref><ref>{{cite news |first=Gareth |last=Lewis |title=Sheep worrying leads to warning from farmers |url=http://www.dailyecho.co.uk/debusiness/news/display.var.1980009.0.sheep_worrying_leads_to_warning_from_farmers.php |work=The Daily Echo |date= 2008-01-21 |accessdate=2008-01-21 }}</ref><ref name="canids">{{cite book |title=The Biology and Conservation of Wild Canids |last=Macdonald |first=David Whyte |coauthors=Claudio Sillero-Zubiri |year=2004 |publisher=Oxford University Press |isbn=0198515553 }}</ref> Other animals that occasionally prey on sheep include: felines, bears, birds of prey, ravens and [[Razorback|feral hogs]].<ref>Simmons & Ekarius, p. 124.</ref><ref name="nass">{{Cite web| date= 2005-05-06 |title=Sheep and Goats Death Loss | publisher=[[National Agricultural Statistics Service]] |url=http://usda.mannlib.cornell.edu/MannUsda/viewDocumentInfo.do?documentID=1628 |accessdate=2007-12-27}}</ref>
  
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Sheep producers have used a wide variety of measures to combat predation. Pre-modern shepherds used their own presence, [[livestock guardian dog]]s, and protective structures such as barns and fencing. Fencing (both regular and [[Electric fence|electric]]), penning sheep at night and lambing indoors all continue to be widely used.<ref name="living"/> More modern shepherds used guns, [[Animal trapping|traps]], and poisons to kill predators,<ref>Simmons & Ekarius, p. 131.</ref> causing significant decreases in predator populations. In the wake of the environmental and conservation movements, the use of these methods now usually falls under the purview of specially designated government agencies in most developed countries .<ref>{{cite web |url=http://www.aphis.usda.gov/lpa/pubs/fsheet_faq_notice/fs_wspredation.html |title=Effects of Wildlife Services on Predator Populations |month=October | year=2001 |publisher=Wildlife Services |accessdate=2008-01-24 }}</ref>
  
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The 1970s saw a resurgence in the use of livestock guardian dogs and the development of new methods of predator control by sheep producers, many of them non-lethal.<ref name="modern"/> Donkeys and [[guard llama]]s have been used since the 1980s in sheep operations, using the same basic principle as livestock guardian dogs.<ref name="storey"/> Interspecific pasturing, usually with larger livestock such as cattle or horses, may help to deter predators, even if such species do not actively guard sheep.<ref name="living"/> In addition to animal guardians, contemporary sheep operations may use non-lethal predator deterrents such as motion-activated lights and noisy alarms.<ref name="storey"/>
  
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====Animal welfare concerns====
  
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The Australian sheep industry is the only sector of the industry to receive international criticism for its practices. [[Sheep station]]s in Australia are cited in ''[[Animal Liberation (book)|Animal Liberation]]'', the seminal book of the [[animal rights movement]], as the author's primary evidence in his argument against retaining sheep as a part of [[animal agriculture]].<ref>{{cite book |title=Animal Liberation |last=Singer |first=Peter |authorlink=Peter Singer |year=1991 |publisher=Avon Books |isbn=0380713330 }}</ref> The practice of [[mulesing]], in which skin is cut away from an animal's [[Perineum|perineal]] area to prevent cases of the fatal condition [[flystrike]], has been condemned by [[PETA]] as being painful and unnecessary.<ref name="ng"> {{cite news |url= http://news.nationalgeographic.com/news/2005/08/0816_050816_woolboycott.html |title = Wool Boycott Targets Australia Sheep Farmers |date = [[2005-08-16]] |accessdate = 2007-12-07 |publisher=[[National Geographic News]]}}</ref> In response, a program of phasing out mulesing is currently being implemented,<ref>{{cite web | url=http://www.australianwoolgrowers.com.au/news2004/news081104.html | title = In the News | date = [[2004-11-08]] | accessdate = 2007-01-09 | author = Peter Wilkinson | publisher = Australian Wool Growers Association }}</ref> and some mulesing operations are being carried out with the use of anaesthetic.<ref name=Farmonline>{{cite web |title=Pain relief from man to lamb|url=http://sl.farmonline.com.au/news/state/agribusiness-and-general/general/pain-relief-from-man-to-lamb/13113.aspx |author=Cuming, Marius |publisher=Stock and Land |date=[[2007-03-16]] |accessdate = 2008-08-11}}</ref> The Animal Welfare Advisory Committee to the [[New Zealand Ministry of Agriculture]] ''Code of recommendations and minimum standards for the welfare of Sheep'', considers mulesing a "special technique" which is performed on some Merino sheep at a small number of farms in New Zealand.<ref>[http://www.biosecurity.govt.nz/animal-welfare/codes/sheep/index.htm#E22E7 Code of recommendations and minimum standards for the welfare of Sheep] Retrieved 1 October 2008</ref>
  
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Most of the sheep meat exported from Australia is either frozen carcases to the UK or live animals to the [[Middle East]]. Shipped on converted [[Tanker (ship)|oil tankers]] in what has been called crowded, unsafe conditions by critics, live sheep are desired by Middle Eastern nations to meet the requirements of ritual [[halal]] slaughter.<ref name="peta"/> Opponents of the export—such as PETA—say that sheep exported to countries outside the jurisdiction of Australia's [[animal cruelty]] laws are treated with horrendous brutality and that halal facilities exist in Australia to make export of live animals redundant.<ref name="peta">{{cite web |url=http://www.savethesheep.com/ |title=Savethesheep.com |accessdate=2007-12-07 |work=[[PETA]] }}</ref> A few celebrities and companies have pledged to [[boycott]] all Australian sheep products in protest.<ref name= "Pink">{{cite news |url= http://news.bbc.co.uk/2/hi/entertainment/6196691.stm |title = Pink angers Australian government |date =[[2006-12-20]]|accessdate = 2007-01-09 |publisher=[[BBC News]]}}</ref>
  
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==In science==
  
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{{seealso|U.S. Sheep Experiment Station}}
  
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Sheep are generally too large and reproduce too slowly to make ideal research subjects, and thus are not a common [[model organism]].<ref name=EU2005>{{cite web | title =Fifth Report on the Statistics on the Number of Animals used for Experimental and other Scientific Purposes in the Member States of the European Union | publisher = Commission of the European Communities| format =PDF | url = http://ec.europa.eu/environment/chemicals/lab_animals/pdf/5th_stat_rep_lab_animals_en.pdf| month =November | year =2007 | accessdate =2008-02-10 }}</ref> They have, however, played an influential role in some fields of science. In particular, the [[Roslin Institute]] of [[Edinburgh, Scotland]] used sheep for [[genetics]] research that produced groundbreaking results. In 1995, two ewes named [[Megan and Morag (cloned sheep)|Megan and Morag]] were the first mammals [[Cloning|cloned]] from [[Cellular differentiation|differentiated cells]]. A year later, a [[Finnish Dorset]] sheep named [[Dolly (sheep)|Dolly]], dubbed "the world's most famous sheep" in ''[[Scientific American]]'',<ref>{{cite news|url=http://www.sciam.com/article.cfm?id=no-more-cloning-around|title=No More Cloning Around|last=Lehrman |first=Sally|date=July 2008|work=[[Scientific American]]|accessdate=2008-09-21}}</ref> was the first mammal to be [[cloned]] from an adult [[somatic cell]]. Following this, [[Polly and Molly]] were the first mammals to be simultaneously cloned and [[transgenic]]. As of 2008, the sheep [[genome]] has not been fully sequenced, although a detailed [[genetic linkage|genetic map]] has been published,<ref>{{cite journal |author=de Gortari MJ, Freking BA, Cuthbertson RP, ''et al'' |title=A second-generation linkage map of the sheep genome |journal=Mamm. Genome |volume=9 |issue=3 |pages=pp. 204–09 |year=1998 |pmid=9501303 |doi=10.1007/s003359900726}}</ref> and a draft version of the complete genome produced by assembling sheep DNA sequences using information given by the genomes of other mammals.<ref>{{cite journal |author=Dalrymple BP, Kirkness EF, Nefedov M, ''et al'' |title=Using comparative genomics to reorder the human genome sequence into a virtual sheep genome |journal=Genome Biol |volume=8 |issue=7 |pages=R152 |year=2007 |pmid=17663790 | doi = 10.1186/gb-2007-8-7-r152}}</ref>
  
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In the study of [[natural selection]], the population of Soay sheep that remain on the island of [[Hirta]] have been used to explore the relation of body size and coloration to reproductive success.<ref>{{cite news |first=Henry |last=Fountain |title=In a Sheep Population, Researchers Find a Fitness Gene |url=http://www.nytimes.com/2008/01/22/science/22obshee.html?ref=science |work= The New York Times |date=2008-01-22 |accessdate=2008-02-05 }}</ref> Soay sheep come in several colors, and researchers investigated why the larger, darker sheep were in decline; this occurrence contradicted the rule of thumb that larger members of a population tend to be more successful reproductively.<ref>{{cite news |first=Ian |last=Sample |title=Soays' natural selection on the hoof |url=http://www.guardian.co.uk/science/2008/jan/18/genetics |work=[[The Guardian]] |date=2008-01-18 |accessdate=2008-02-05 }}</ref> The feral Soays on Hirta are especially useful subjects because they are isolated.<ref>{{cite news |first=Nic |last=Fleming |title=Darker black sheep's decline is in the genes |url=http://www.telegraph.co.uk/earth/main.jhtml?view=DETAILS&grid=&xml=/earth/2008/01/18/scisheep118.xml |work=[[The Daily Telegraph]] |date=2008-01-18 |accessdate=2008-02-05 }}</ref>
  
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Sheep are one of the few animals where the molecular basis of the diversity of male sexual preferences has been examined.<ref>{{cite journal |author=Roselli CE, Larkin K, Resko JA, Stellflug JN, Stormshak F |title=The volume of a sexually dimorphic nucleus in the ovine medial preoptic area/anterior hypothalamus varies with sexual partner preference |journal=Endocrinology |volume=145 |issue=2 |pages=pp. 478–83 |year=2004 |pmid=14525915 |doi=10.1210/en.2003-1098}}</ref> However, this research has been controversial, and much publicity has been produced by a study at the [[Oregon Health and Science University]] that investigated the mechanisms that produce homosexuality in rams. Organizations such as PETA campaigned against the study, accusing scientists of trying to cure homosexuality in the sheep.<ref name="nyt">{{cite news |first=John |last=Schwartz |title=Of Gay Sheep, Modern Science and Bad Publicity |url=http://www.nytimes.com/2007/01/25/science/25sheep.html |work=[[The New York Times]] |date=[[2007-01-25]] |accessdate=2007-12-07 }}</ref> OHSU and the involved scientists vehemently denied such accusations.<ref name="nyt"/> [[Image:Faroe stamp 036 ram.jpg|thumb|right|A 1979 [[Faroe Islands|Faroese]] stamp by [[Czesław Słania]]. Sheep are the [[heraldic]] animal of the Faroes ("Sheep Islands").]]
  
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Domestic sheep are sometimes used in medical research, particularly for researching cardiovascular physiology, in areas such as [[hypertension]] and [[heart failure]].<ref>{{cite journal |author=Recchia FA, Lionetti V |title=Animal models of dilated cardiomyopathy for translational research |journal=Vet. Res. Commun. |volume=31 Suppl 1 |pages=pp. 35–41 |year=2007 |pmid=17682844 |doi=10.1007/s11259-007-0005-8}}</ref><ref>{{cite journal |author=Hasenfuss G |title=Animal models of human cardiovascular disease, heart failure and hypertrophy |journal=Cardiovasc. Res. |volume=39 |issue=1 | pages = 60 |year=1998 |pmid=9764190 | doi = 10.1016/S0008-6363(98)00110-2}}</ref> Pregnant sheep are also a useful model for human pregnancy,<ref>{{cite journal |author=Barry JS, Anthony RV |title=The pregnant sheep as a model for human pregnancy |journal=Theriogenology |volume=69 |issue=1 |pages=pp. 55–67 |year=2008 |pmid=17976713}}</ref> and have been used to investigate the effects on fetal development of [[malnutrition]] and [[Hypoxia (medical)|hypoxia]].<ref>{{cite journal |author=Vuguin PM |title=Animal models for small for gestational age and fetal programming of adult disease |journal=Horm. Res. |volume=68 |issue=3 | pages = 113 |year=2007 |pmid=17351325 | doi = 10.1159/000100545}}</ref> In [[behavioral sciences]], sheep have been used in isolated cases for the study of [[Face perception|facial recognition]], as their mental process of recognition is qualitatively similar to humans.<ref>{{cite journal |author=Peirce JW, Leigh AE, daCosta AP, Kendrick KM. |year=2001 |month=June |title=Human face recognition in sheep: lack of configurational coding and right hemisphere advantage. |journal= Behavioural processes |pmid=11390088 | volume = 55 | pages = 13 | doi = 10.1016/S0376-6357(01)00158-9}}</ref>
  
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===In religion and folklore===
  
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In antiquity, symbolism involving sheep cropped up in religions in the [[ancient Near East]], the [[Mideast]], and the [[Mediterranean]] area: Catal Huyuk, ancient Egyptian religion, the Cana'anite and Phoenician tradition, [[Judaism]], [[Greek mythology|Greek religion]], and others. Religious symbolism and ritual involving sheep began with some of the first known faiths: skulls of rams (along with bulls) occupied central placement in shrines at the [[Çatalhöyük]] settlement in 8,000 BCE.<ref>Budiansky, p. 159.</ref> In [[Ancient Egyptian religion]], the ram was the symbol of several gods: [[Khnum]], [[Heryshaf]] and [[Amun]] (in his incarnation as a god of [[fertility]]).<ref name="hobby"/> Other deities occasionally shown with ram features include: the goddess [[Ishtar]], the [[Phoenicia]]n god Baal-Hamon, and the Babylonian god Ea-Oannes.<ref name="hobby"/> In Madagascar, sheep were not eaten as they were believed to be incarnations of the souls of ancestors.<ref name = Cooper92>{{cite book |last=Cooper |first=JC |title=Symbolic and Mythological Animals |pages=p. 219 |year=1992 |publisher= Aquarian Press |location=London |isbn=1-85538-118-4}}</ref>
  
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There are also many ancient Greek references to sheep: that of [[Chrysomallos]], the golden-fleeced ram, continuing to be told through into the modern era. [[Astrology|Astrologically]], ''[[Aries (astrology)|Aries]]'', the ram, is the first sign of the classical Greek [[zodiac]] and the sheep is also the eighth of the twelve animals associated with the 12-year cycle of in the [[Chinese zodiac]], related to the [[Chinese calendar]].<ref name = Cooper92/> In [[Mongolia]], [[shagai]] are an ancient form of dice made from the [[cuboid bone]]s of sheep that are often used for fortunetelling purposes.
  
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[[Image:Liten askenasisk sjofar 5380.jpg|thumb|right|150px|A ram's horn shofar]]
  
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Sheep play an important role in all the Abrahamic faiths; [[Abraham]], [[Isaac]], [[Jacob]], [[Moses]], and [[King David]] were all shepherds. According to the story of the [[Binding of Isaac]], a ram is sacrificed as a substitute for Isaac after an angel stays Abraham's hand. [[Eid al-Adha]] is a major annual festival in [[Islam]] in which sheep (or other animals) are sacrificed in remembrance of this act.<ref name="Eid">{{cite web | title = Eid ul Adha (10 Dhul-Hijja) - the festival of sacrifice| publisher = BBC| url = http://www.bbc.co.uk/religion/religions/islam/holydays/eiduladha.shtml| accessdate = 2008-01-08}}</ref><ref name="sweetness">{{cite web | title = Eid Festival Around The World - Graphic photos| publisher = Sweetness & Light| url = http://sweetness-light.com/archive/the-eid-festival-around-the-world-graphic-photos| accessdate = 2008-01-08}}</ref> Sheep are also occasionally sacrificed to commemorate important [[secular]] events in Islamic cultures.<ref>{{cite news|url=http://baghdadbureau.blogs.nytimes.com/2008/08/13/bloody-blessing-goes-unnoticed/?scp=8&sq=sheep&st=cse|title=Bloody Blessing Goes Unnoticed|last=Robertson|first=Cambpell |date=August 13, 200|work=[[The New York Times]]|accessdate=2008-09-10}}</ref> Greeks and Romans also sacrificed sheep regularly in religious practice, and [[Judaism]] also once sacrificed sheep as a [[Korban]] (sacrifice), such as the [[Korban Pesach|Passover lamb]] .<ref name = Cooper92/> Ovine symbols—such as the ceremonial blowing of a [[shofar]]—still find a presence in modern Judaic traditions. Followers of [[Christianity]] are collectively often referred to as a flock, with Christ as the [[The Good Shepherd (Christianity)|Good Shepherd]], and sheep are an element in the Christian [[iconography]] of the [[Nativity of Jesus in art|birth of Jesus]]. Some Christian [[saint]]s are considered [[Patron saints of occupations and activities|patrons of shepherds]], and even of sheep themselves. Christ is also portrayed as the [[Sacrificial lamb]] of God (''[[Agnus Dei]]'') and Easter celebrations in [[Greece]] and [[Romania]] traditionally feature a meal of Paschal lamb.
  
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==See also==
  
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==References==
  
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* {{cite book |title=The Covenant of the Wild: Why animals chose domestication |last=Budiansky |first=Stephen |year=1999 |publisher=Yale University Press |isbn=0300079931}}
  
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*{{cite book|title=Sheep and Goat Science, Fifth Edition|last=Ensminger|first=Dr. M.E.|coauthors= Dr. R.O. Parker|year=1986|publisher=The Interstate Printers and Publishers Inc |location=Danville, Illinois|isbn=081342464X}}
  
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* {{cite book |title=Storey's Guide to Raising Sheep |last=Simmons |first=Paula |coauthors=Carol Ekarius |year=2001 |publisher=Storey Publishing LLC |location=North Adams, MA |isbn=9781580172622}}
  
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* {{cite book |title= Beginning Shepherd's Manual, Second Edition|last=Smith M.S. |first=Barbara |coauthors=Mark Aseltine PhD, Gerald Kennedy DVM |year=1997 |publisher=Iowa State University Press |location=Ames, Iowa |isbn=081382799X}}
  
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* {{cite book |title=Sheep: small-scale sheep keeping for pleasure and profit |last=Weaver |first=Sue |year=2005 |publisher=Hobby Farm Press, an imprint of BowTie Press, a division of BowTie Inc. |location=3 Burroughs Irvine, CA 92618 |isbn=1-931993-49-1 }}
  
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* {{cite book |title=Living with Sheep: Everything You Need to Know to Raise Your Own Flock |last=Wooster |first=Chuck |coauthors=Geoff Hansen (Photography) |year=2005 |publisher=The Lyons Press |location=Guilford, Connecticut |isbn= 1-59228-531-7}}
  
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==Notes==
  
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{{reflist|2}}
  
   
 
==External links==
  
==External links==
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*[http://www.fas.usda.gov/dlp2/circular/1998/98-10LP/sheep3.htm Miller, S. 1998. "Sheep and Goats". United States Department of Agriculture, Foreign Agricultural Service]
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{{wikispecies|Ovis aries}}
  
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*[http://www.ansi.okstate.edu/breeds/sheep Oklahoma State University (OSU). 2003 Breeds of Livestock: Sheep] Retrieved January 13, 2007
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*[http://www.ultimateungulate.com Huffman, B. 2006. ''The Ultimate Ungulate Page'' Website] Retrieved January 13, 2007
   
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This article refers to the sheep genus. For the species commonly referred to simply as "sheep", see Domestic sheep.
?Sheep
Bighorn Sheep
Bighorn Sheep
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Bovidae
Subfamily: Caprinae
Genus: Ovis
Linnaeus, 1758
Species

See text.

A sheep is an individual of any of the five or more mammal species that comprise the genus Ovis, part of the goat-antelope subfamily. Sheep are bovids (members of the family Bovidae) and ruminants, meaning they chew cud. The domestic sheep is thought to be descended from the wild mouflon of central and southwest Asia. Members of the genus are highly gregarious.

Female sheep are called ewes, males are called rams (sometimes also called bucks or tups) and young sheep are called lambs. The adjective applying to sheep is ovine and the collective term for sheep is flock or mob. The term herd is also occasionally used in this sense. See Glossary of sheep husbandry for other terms related to domestic sheep.

Sheep are usually stockier than other bovines and some have horns which are more divergent than those of goats. Sheep have scent glands on the face and hind feet. Communication through the scent glands is not well understood but is thought to be important for sexual signaling. Males can smell females which are fertile and ready to mate, and rams mark their territories by rubbing scent on to rocks. They have a four-chambered stomach which plays a vital role in digesting, regurgitating, and redigesting food. Domestic sheep are important for their wool, milk, and meat (which is called mutton or lamb).

Five species and numerous subspecies of sheep are currently recognized, although some subspecies have also been considered full species. The following are the main ones:[1]

File:Argali.jpg Ovis ammon Argali
File:Ovis orientalis aries 'Skudde' (aka).jpg Ovis aries aries[2] Domestic sheep
File:Mouflon 2.jpg Ovis orientalis orientalis group Mouflon
File:Ovis ammon vignei arkal Pretoria 3.jpg Ovis orientalis vignei group Urial
File:Ovis canadensis 2.jpg Ovis canadensis Bighorn sheep
File:2005 04 27 1582 Dall Sheep.jpg Ovis dalli Dall Sheep
Ovis nivicola Snow sheep

Wild sheep are 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 lb) (Nowak 1983). Their diet consists mainly of grasses, as well as other plants and lichens. Like other bovids their digestive system enables them to digest and live on low-quality, rough plant materials. Sheep conserve water well and can live in fairly dry environments. Their bodies are covered by a coat of thick hair to protect them from cold. The coat contains long, stiff hairs, called kemps, and a short woolly undercoat, called fleece, which grows in fall and is shed in spring.[3]

Wild sheep are social animals and live in groups, 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 [3].

In wild sheep both rams and ewes have horns, with those of rams being much larger. The horns of a mature bighorn ram can weigh 14 kg (30 lb) – as much as the rest of its bones put together. 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.[4]

Wild sheep have very keen senses of sight and hearing. When detecting predators wild sheep most often flee, usually uphill to higher ground. However they can also fight back. The Dall sheep has been known to butt wolves off the face of cliffs.[4]

See also

  • Barbary Sheep (Ammotragus lervia), another type of goat antelope, not closely related to Ovis sheep.
  • Blue sheep or bharal (Pseodois), two species of goat antelopes, not closely related to Ovis sheep.
  • Domestic sheep

References

Because of their economic importance and ease of access most psychological orientated resarch on sheep has been conducted on the domestic sheep so the majority of references are in that article.

  1. ↑ Wilson & Reeder's Mammal species of the world 3rd edition online
  2. ↑ ICZN (International Commission on Zoological Nomenclature) opinion 2027
  3. ↑ 3.0 3.1 Clutton-Brock, J. 1999. A Natural History of Domesticated Mammals. Cambridge, UK : Cambridge University Press ISBN 0521634954
  4. ↑ 4.0 4.1 Voelker, W. 1986. The Natural History of Living Mammals. Medford, New Jersey: Plexus Publishing, Inc. ISBN 0937548081
  • Bulanskey, S. 1992. The Covenant of the Wild. New York: William Morrow and Company, Inc. ISBN 0688096107
  • Ciuti, S., Pipia, A., Ghiandai, F., Grignolio, S., & Apollonio, M. (2008). The key role of lamb presence in affecting flight response in Sardinian mouflon (Ovis orientalis musimon): Behavioural Processes Vol 77(3) Mar 2008, 408-412.
  • Green, D. J. (2005). Review of Soay Sheep: Dynamics and Selection in an Island Population: Applied Animal Behaviour Science Vol 93(1-2) Sep 2005, 179-180.
  • Mooring, M. S., Hart, B. L., Fitzpatrick, T. A., Reisig, D. D., Nishihira, T. T., Fraser, I. C., et al. (2006). Grooming in desert bighorn sheep (Ovis Canadensis Mexicana) and the ghost of parasites past: Behavioral Ecology Vol 17(3) May-Jun 2006, 364-371.
  • Langbein, J., Streich, J., & Scheibe, K. M. (1998). Characteristic activity patterns of female mouflons (Ovis orientalis musimon) in the lambing period: Applied Animal Behaviour Science Vol 58(3-4) Jul 1998, 281-292.
  • Loehr, J., Carey, J., Ylonen, H., & Suhonen, J. (2008). Coat darkness is associated with social dominance and mating behaviour in a mountain sheep hybrid lineage: Animal Behaviour Vol 76(5) Nov 2008, 1545-1553.
  • Nowak, R. M. and J. L. Paradiso. 1983. Walker's Mammals of the World. Baltimore, Maryland: The Johns Hopkins University Press. ISBN 0801825253
  • Parker, D. 2001. The Sheep Book. Athens, Ohio, USA : Ohio University Press ISBN 0804010323
  • Perez-Barberia, F. J., Walker, D. M., & Marion, G. (2007). Maximizing intake under challenging foraging conditions at two spatial scales in Soay sheep: Animal Behaviour Vol 73(2) Feb 2007, 339-348.
  • Toomer, E. E. (1997). The ethological characteristics and habitat of the desert bighorn sheep. Dissertation Abstracts International: Section B: The Sciences and Engineering.



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