Sheep

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Sheep

A flock of sheep.

Conservation status

Domesticated

Scientific classification

Kingdom: Animalia

Phylum: Chordata

Class: Mammalia
 Order: Artiodactyla

Family: Bovidae

Subfamily: Caprinae

Genus: Ovis

Species: O. aries

Binomial name

Ovis aries
Linnaeus, 1758

The sheep (Ovis aries) is a quadrupedal, ruminant mammal typically kept as livestock. Like all
ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. Although the
name "sheep" applies to many species in the genus Ovis, in everyday usage it almost always refers
to Ovis aries. Numbering a little over one billion, domestic sheep are also the most numerous
species of sheep. An adult female sheep is referred to as a ewe (/juː/), an intact male as a ram or
occasionally a tup, a castrated male as a wether, and a younger sheep as a lamb.
Sheep are most likely descended from the wild mouflon of Europe and Asia. One of the earliest
animals to be domesticated for agriculturalpurposes, sheep are raised for fleece, meat (lamb, hogget
or mutton) and milk. A sheep's wool is the most widely used animal fiber, and is usually harvested
by shearing. Ovine meat is called lamb when from younger animals and mutton when from older
ones. Sheep continue to be important for wool and meat today, and are also occasionally raised
for pelts, as dairy animals, or as model organisms for science.
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 American nations, and the British Isles are most closely associated with sheep
production.
Sheepraising has a large 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. Many
other specific terms for the various life stages of sheep exist, generally related to lambing, shearing,
and age.
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, Arcadian imagery. Sheep figure in many mythologies—such as
the Golden Fleece—and major religions, especially the Abrahamic traditions. In both ancient and
modern religious ritual, sheep are used as sacrificial animals.

Contents
 [hide]

 1Characteristics
o 1.1Comparison with goats
o 1.2Breeds
 2Diet
o 2.1Grazing behavior
 3Behavior
o 3.1Flock behavior
o 3.2Dominance hierarchy
o 3.3Intelligence and learning ability
o 3.4Vocalisations
o 3.5Senses
 4Reproduction
 5Health
o 5.1Predators
 6Economic importance
 7As food
 8In science
 9Cultural impact
o 9.1Religion and folklore
 10Gallery
 11See also
 12References
 13Sources
 14External links

Characteristics
See also: History of the domestic sheep
Domestic sheep are relatively small ruminants, usually with a crimped hair called wool and often with
horns forming a lateral spiral. Domestic sheep differ from their wild relatives and ancestors in several
respects, having become uniquely neotenic as a result of selective breeding by humans.[1][2] 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 (i.e. polled), or horns in both sexes,
or in males only. Most horned breeds have a single pair, but a few breeds may have several.[3]
Another trait unique to domestic sheep as compared to wild ovines is their wide variation in color.
Wild sheep are largely variations of brown hues, and variation within species is extremely limited.
Colors of domestic sheep range from pure white to dark chocolate brown, and even spotted
or piebald.[4][5] 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.[4][5] While white wool is desirable for
large commercial markets, there is a niche market for colored fleeces, mostly for handspinning.[6] The
nature of the fleece varies widely among the breeds, from dense and highly crimped, to long and
hairlike. 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 fibre.
Suffolks are a medium wool, black-faced breed of meat sheep that make up 60% of the sheep population in the
U.S.[7]

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.[7] Ewes typically weigh between 45
and 100 kilograms (100 and 220 lb), and rams between 45 and 160 kilograms (100 and
350 lb).[8] When all deciduous teeth have erupted, the sheep has 20 teeth.[9] Mature sheep have 32
teeth. As with other ruminants, the front teeth in the lower jaw bite against a hard, toothless pad in
the upper jaw. These are used to pick off vegetation, then the rear teeth grind it before it is
swallowed. There are eight lower front teeth in ruminants, but there is some disagreement as to
whether these are eight incisors, or six incisors and two incisor-shaped canines. This means that
the dental formula for sheep is either 0.0.3.34.0.3.3 or 0.0.3.33.1.3.3 [10] There is a
large diastema between the incisors and the molars. In the first few years of life one can calculate
the age of sheep from their front teeth, as a pair of milk teeth is replaced by larger adult teeth each
year, the full set of eight adult front teeth being complete at about four years of age. The front teeth
are then 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 life expectancy of a sheep is 10 to 12 years, though some sheep may
live as long as 20 years.[3][11][12]

Skull

Sheep have good hearing, and are sensitive to noise when being handled.[13] Sheep have horizontal
slit-shaped pupils, with excellent peripheral vision; with visual fields of about 270° to 320°, sheep can
see behind themselves without turning their heads.[6][14] Many breeds have only short hair on the face,
and some have facial wool (if any) confined to the poll and or the area of the mandibular angle; the
wide angles of peripheral vision apply to these breeds. A few breeds tend to have considerable wool
on the face; for some individuals of these breeds, peripheral vision may be greatly reduced by "wool
blindness", unless recently shorn about the face.[15] Sheep have poor depth perception; shadows and
dips in the ground may cause sheep to baulk. In general, sheep have a tendency to move out of the
dark and into well-lit areas,[16] and prefer to move uphill when disturbed. 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,[17] but those on the face
may be used in breeding behaviors.[7] The foot glands might also be related to reproduction,[7] 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.[17]
Comparison with goats
Sheep and goats are closely related: both are in the subfamily Caprinae. However, they are
separate species, so hybrids rarely occur, and are always infertile. A hybrid of a ewe and a buck (a
male goat) is called a sheep-goat hybrid (only a single such animal has been confirmed), and is not
to be confused with the sheep-goat chimera, though both are known as geep. Visual differences
between sheep and goats include the beard of goats and divided upper lip of sheep. Sheep tails also
hang down, even when short or docked, while the short tails of goats are held upwards. Also, sheep
breeds are 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, whereas rams do not.[12]