Sheep, Sheep

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Like all ruminants, sheep are members of the order Artiodactyla, the even-toed ungulates. 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 their genus.

One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleece, meat (lamb or mutton) and milk. A sheep's wool is the most widely used of any animal, and is usually harvested by shearing. Ovine meat is called lamb when from younger animals and mutton when from older ones.

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. Sheep-raising 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 scap ; 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, 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.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 mythologiessuch as the Golden Fleeceand major religions, especially the Abrahamic traditions. In both ancient and modern religious ritual, sheep are used as sacrificial animals. In contemporary English language usage, people who are timid, easily led, or stupid are often compared to sheep.

Domestic sheep differ from their wild relatives and ancestors in several respects, having become uniquely neotenic as a result of man's influence. Budiansky, pp. 9798.

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.

However, colored sheep do appear in many modern breeds, and may even appear as a recessive trait in white flocks.

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.

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. Ensminger Smith et al.

In general, sheep have a tendency to move out of the dark and into well-lit areas.

However, they are separate species, so hybrid 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 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 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, whereas rams do not.

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.

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 capabilitiesthey 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 mules, which can then be crossed with meat-type rams to produce prime market lambs.

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, and the breed continues to dominate the world sheep industry.

DArcy, J.B., Sheep Management & Wool Technology, NSW University Press, 1986, ISBN 0 86840 106 4 Some major medium wool breeds, such as the 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 breed was developed by crossing Lincoln rams (a long wool breed) with fine-wooled Rambouillet ewes.

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.

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.

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, 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.

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 carbohydrates. When sheep graze, vegetation is chewed into a mass called a bolus, which is then passed into the first chamber: the rumen. The rumen is a 5- to 10-gallon (1938 l) organ in which feed is fermented via a symbiotic relationship with the bacteria, protozoa, and yeasts of the gut flora. Simmons & Ekarius, p. 146.

Common plants toxic to sheep are present in most of the world, and include (but are not limited to) oak and acorns, tomato, yew, rhubarb, potato, and rhododendron. Simmons & Ekarius, p. 160. Sheep are largely grazing herbivores, unlike 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.

The ability to thrive solely on pasture (even without hay) varies with breed, but all sheep can survive on this diet.

The amount of water needed by sheep fluctuates with the season and the type and quality of the food they consume. Wooster, p. 64.

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 scum or algae.

Especially in industrialized countries, sheep producers may fatten market lambs before slaughter (called "finishing") in feedlots.

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. Budiansky All sheep have a tendency to congregate close to other members of a flock, although this behavior varies with breed.

Sheep are also extremely food-oriented, and association of humans with regular feeding often results in sheep soliciting people for food. Budiasnky p. 100 et al.

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.

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 trough. Simmons & Ekarius, p. 8.

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.

As a prey species, a sheep's system is adapted to hide the obvious signs of illness, to prevent being targeted by predators.

Wooster Many breeders take a variety of preventative measures to warn 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.

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.

Both external and internal parasites are the most prevalent malady in sheep, and are either fatal, or reduce the productivity of flocks.

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 drenches 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.

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 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 backliner, sprays or immersive sheep dips.

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 membranes. Ovine rinderpest (or peste des petits ruminants ) is a highly contagious and often fatal viral disease affecting sheep and goats.

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 devastate 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.

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.

In the United States, for instance, over 1/3 of sheep deaths in 2004 were caused by predation.

Archaeological evidence from statuary found at sites in Iran suggests that selection for woolly sheep may have begun around 6000 BC, but the earliest woven wool garments have only been dated to two to three thousand years later. Smith et al., p. 8.

Primitive sheep cannot be shorn, and must have their wool plucked out by hand in a process called "rooing". This is because fibers called kemps are still longer than the soft fleece. The fleece may also be collected from the field after it falls out. This trait survives today in unrefined breeds such as the Soay. Indeed, the Soay, along with other Northern European breeds with short tails, unshearable fleece, diminutive size, and horns in both sexes, are closely related to ancient sheep. Originally, weaving and spinning wool was a handicraft practiced at home, rather than an industry. Babylonians, Sumerians, and Persians all depended on sheep; and although linen was the first fabric to be fashioned in to clothing, wool was a prized product. The raising of flocks for their fleece was one of the earliest industries, and flocks were a medium of exchange in barter economies. Numerous biblical figures kept large flocks, and subjects of the king of Israel were taxed according to the number of rams they owned.

South African sheep producers, in an attempt to deal with the numerous predators of Africa, invented the livestock protection collar, which holds poison at the jugular to sicken or kill predators.

Pliny the Elder, in his Natural History ( Naturalis Historia ), speaks at length about sheep and wool.

Exportation of merinos without royal permission was also a punishable offense, thus ensuring a near-absolute monopoly on the breed until Napoleon's invasion of Spain in the mid-18th century. After the breaking of the export ban, fine wool sheep began to be distributed worldwide. The export to Rambouillet by Louis XVI in 1786 formed the basis for the modern Rambouillet (or French Merino) breed. Simmons & Ekarius, p. 66.

The management model used in England was quite different but had a similar importance to economy of the British Empire. Up until the early 20th century, owling (the smuggling of sheep or wool out of the country) was a punishable offense, and to this day the Lord Speaker of the House of Lords sits on a cushion known as the Woolsack.

Before his time, breeding for desirable traits was often based on chance, with no scientific process for selection of breeding stock. Bakewell established the principles of selective breedingespecially line breedingin his work with sheep, horses and cattle; his work later influenced Gregor Mendel and Charles Darwin.

Placing semi-feral sheep and goats on islands was common practice in colonization during this period.

Another effect of the westward movement of sheep flocks in North America was the decline of wild species such as Bighorn sheep ( O. canadesis ). Most diseases of domestic sheep are transmittable to wild ovines, and such diseases, along with overgrazing and habitat loss, are named as primary factors in the plummeting numbers of wild sheep.

New Zealand has the highest density of sheep per capita (sheep outnumber the human population 12 to 1), and Australia is the world's indisputably largest exporter of sheep and cattle.

In 1820, the continent held 100,000 sheep, a decade later it had one million.

New Zealand flocks are kept in a fashion similar to English ones, in fenced holdings without shepherds. Although wool was once the primary income source for New Zealand sheep owners (especially during the New Zealand wool boom), today it has shifted to meat production for export.

Sheep stations in Australia are cited in 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.

Shipped on livestock carriers 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.

Byproducts from the slaughter of sheep are also of value: sheep tallow can be used in candle and soap making, sheep bone and cartilage has been used to furnish carved items such as dice and buttons as well as rendered glue and gelatin. Simmons & Ekarus p. 325329 Sheep intestine can be formed into sausage casings, and lamb intestine has been formed into surgical suture, as well as strings for musical instruments and tennis rackets.

Simmons & Ekarius p. 322 Farmers may also choose to focus on a particular breed of sheep in order to sell registered purebred animals, as well as provide a ram rental service for breeding. Simmons & Ekarius p. 333 A new option for deriving profit from live sheep is the rental of flocks for grazing; these "mowing services" are hired in order to keep unwanted vegetation down in public spaces and to lessen fire hazard. Simmons & Ekarius p. 332334 Despite the falling demand and price for sheep products in many markets, sheep have distinct economic advantages when compared with other livestock. They do not require the expensive housing, Smith et al., p. 31.

This became the name for sheep meat in English, while the Old English word sceap was kept for the live animal.

Sheep testiclescalled animelles or lamb friesare considered a delicacy in many parts of the world. Perhaps the most unusual dish of sheep meat is the Scottish haggis, composed of various sheep innards cooked along with oatmeal and chopped onions inside its stomach. Smith et al., p. 147.

Sheep have only two teats, and produce a far smaller volume of milk than cows.

Yogurts, especially some forms of strained yogurt, may also be made from sheep milk.

A year later, a Finnish Dorset sheep named Dolly, dubbed "the world's most famous sheep" in Scientific American , 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 map has been published, and a draft version of the complete genome produced by assembling sheep DNA sequences using information given by the genomes of other mammals.

Louis Rams and the Dodge Ram. Sheep are key symbols in fables and nursery rhymes like The Wolf in Sheep's Clothing , Little Bo Peep , Baa, Baa, Black Sheep , and Mary Had a Little Lamb . Novels such as George Orwell's Animal Farm , Haruki Murakami's A Wild Sheep Chase , Thomas Hardy's Far from the Madding Crowd and A Sheep Detective Story utilize sheep as characters or plot devices. Poems like William Blake's "The Lamb", songs such as Pink Floyd's "Sheep" and Bach's aria Sheep may safely graze ( Schafe knnen sicher weiden ) use sheep for metaphorical purposes. In more modern popular culture, the 2007 film Black Sheep exploits sheep for horror and comedic effect, ironically turning sheep into blood-thirsty killers.thumb|left|200px|The proverbial black sheep Counting sheep is popularly said to be an aid to sleep, and some ancient systems of counting sheep persist today. Sheep also enter in colloquial sayings and idiom frequently with such phrases as "black sheep". To call an individual a black sheep implies that they are an odd or disreputable member of a group.

Astrologically, 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.

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.

Some Christian saints are considered 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.

Source: Wikipedia > Domestic Sheep