Sheep
| Domestic sheep | |
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| A research flock at US Sheep Experiment Station near Dubois, Idaho | |
Domesticated
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| Species: | O. aries
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| Ovis aries | |
Domestic sheep (Ovis aries) are quadrupedal, cloven-hoofed mammals of the genus Ovis. Sheep were one of the earliest animals to be domesticated for agricultural purposes; primarily for their valuable fleece and meat. A sheep's wool is the most widely used of any animal, and is harvested most commonly by shearing. Ovine meat is called "lamb" when culled from younger animals and "mutton" when from older ones. They continue to be vital livestock internationally, and are also occasionally raised for their pelts, as dairy animals, and as model organisms by science. The most numerous ovine species, they are most likely descended from the wild mouflon.
Sheep husbandry is practiced globally, and has played an important role in many economies throughout time, most notably Australia, New Zealand, Patagonian nations, and the United Kingdom in the modern era. Sheep raising has a very large lexicon of unique terms which differ considerably by region. Use of the name "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. Adult female sheep are referred to as ewes, intact males as rams or tups, castrated males as wethers, and younger sheep as lambs. A group of sheep is called a flock, herd or mob.
Being a key animal in the history of farming, the sheep has a deeply entrenched place in human culture, and finds representation in much modern language and symbology. As livestock, sheep are most-often linked to 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. In contemporary English language usage, people who are timid, easily led, or stupid are often compared to sheep.
Description
Domestic sheep are ruminating bovids, typically with horns forming a lateral spiral and crimped hair called wool. Domestic sheep differ from their wild relatives and ancestors in several respects. Wild sheep have uncrimped hair and short tails. Some primitive breeds of domestic sheep have such tails, but a long tail – along with entirely white wool – seems to have been an early result of domestication. All wild sheep, male and female, have horns. Domestic sheep may have horns (usually two, but sometimes four or more) or be completely polled, depending on breed and gender.[1]
Sheep have a rather wide range of height and weight, largely depending on breed. The rate of a sheep's growth and their eventual mature weight is a highly heritable trait which is often a point of focus for selective breeding.[2] Ewes can weigh 100-225 pounds (45-100 kilos), and rams - being generally larger than ewes - between 100 and 350 pounds (70-160 kilos).[3] Mature sheep have 32 teeth (dental formula: I:0/4 C:0/0 P:3/3 M:3/3). There are six molars and six premolars, all paired in the upper and lower jaws, together forming broad grinding surfaces at the back of the mouth. As in other ruminants, the eight incisors are all in the lower jaw, biting against a hard, toothless pad in the upper jaw; together these are used to pick off vegetation. There are no canines, but there is a large gap where they would be between the incisors and the premolars. Until the age of four (when all the adult teeth have erupted), it is possible to distinguish the age of sheep from their front teeth: a pair of incisors erupts each year. Though some sheep may live as long as 20 years, domestic sheep on normal pasture begin to decline slowly from four years on, the loss of teeth making it progressively harder for them to feed and thus hindering the health and productivity of the animal.[4] The average life expectancy of a sheep is consequently 10-12 years.[1] [5]
Sheep have good hearing, and are sensitive to noise when being handled.[5] Sheep have horizontal slit-shaped pupils, and possess a very wide peripheral field of vision with some ability to distinguish color. With what is estimated to be approximately 270-320° of wide-angle vision, sheep can see behind themselves without turning their heads (though this ability may be impaired slightly by any wool present around the eyes).[6] [7] However, sheep have poor depth perception — shadows and dips in the ground may cause sheep to balk. In general, sheep have a tendency to want to move out of darkness and in to well-lit areas.[8] Sheep have an excellent sense of smell, and – like all species of their genus — have scent glands located on their face just in front of the eyes, and interdigitally on the feet. The purpose of these glands is not known for certain, but those on the face are likely to be related to breeding behavior.[5] The feet glands may also be related to sexual selection, but alternative reasons, such as secretion of a waste product or a scent marker to help lost sheep find their flock, have also been posited.[5]
Sheep and goats are closely related (both are in the subfamily Caprinae), and it can sometimes be difficult to differentiate them by appearance alone. However, the genes of sheep and goats differ so greatly that cross-species hybrids 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 clues to differentiating sheep and goats include the beard and divided upper lip of goats, which sheep do not have. 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) but naturally polled goats are rare (though many are polled artificially). Males of the two species differ especially in that buck goats acquire a unique and very strong odor during the rut, whereas rams do not.[5]
Breeds
The domestic sheep is a multi-purpose animal, and the more than two hundred breeds now in existence were created to serve these diverse purposes.[9] [1] Some sources give a count of a thousand or more breeds, but concrete documentation has not been produced for such a number.[7] [5] Among the breeds, almost all are classified as being suited to furnishing a precise product: either wool, meat, milk, hides or a combination thereof (i.e. dual-purpose breeds). Especially in Africa and Asia, a sheep may be of a fat-tailed breed, which is a type of meat or dual-purpose sheep with larger deposits of fat withing its tail. Other distinctions made in classifying sheep include face color (generally white or black), the presence or lack of horns, and the topography of a breed's origin. This last point is especially stressed in the United Kingdom, where breeds are described as either upland (a.k.a. hill or mountain) or lowland (a.k.a. down) breeds, each traditionally are said to bear characteristics imparted from their respective terrain.[8]
Ovine 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 have good reproductive and mothering capabilities, and are for replacing ewes in standing flocks. Ram breeds are selected for rate of weight gain and carcass quality, and are mated with ewe breeds to produce market lambs. Many breeds, especially rare or primitive ones, fall into neither category strictly. Lowland and upland breeds are also crossed in this fashion, with the hardy hill ewes crossed with larger, fast-growing lowland rams to produce a type of ewe called a mule, which can then be crossed with meat-type rams to produce prime market lambs.[8]
Sheep breeds are categorized by the type of wool they exhibit, distinct from whether they are favored for meat or wool production. Fine wool breeds are those that possess wool of top quality and density, and are consequently preferred by the textile industry. Most of these breeds were derived from Merino sheep. Medium wool breeds have wool between the extremes, and are typically fast-growing meat and ram breeds with dark faces. Some major medium wool breeds, such as the Corriedale, are dual-purpose crosses of long and fine-wooled breeds created for high-production commercial flocks. Long wool breeds are the largest of sheep; with coarse, lengthy wool and a slow rate of maturation. Long wool sheep are most valued by modern agriculture for crossbreeding to improve the attributes of other sheep types. For example: the American Columbia breed was developed through crossing Lincoln rams – a long wool breed – with fine-wooled Rambouillet ewes. Carpet wool sheep are those with a medium to long length wool of characteristic coarseness. Breeds traditionally used for carpet wool show more variability in general traits than other types, the chief requirement being 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 reposition a few of the traditional breeds to alternative purposes. A last class of sheep is that of fur or hair sheep, which do not grow wool at all. Hair sheep are similar to the very early type of domesticated sheep kept before wooly breeds were developed, and are raised for meat and pelts. Some modern breeds of hair sheep, such as the Dorper, are the result of crosses between wooled and hair breeds. Resistant to parasites and needing no shearing, hair-class sheep are increasing in popularity among sheepmeat producers.[5]
Diet
Sheep are exclusively herbivorous mammals. Like all ruminants, sheep have a complex digestive system comprised of four stomachs which allows them to break down otherwise inedible roughage such as stems, leaves, and seed hulls in to complex carbohydrates. Sheep follow a diurnal pattern of activity, beginning to feed at dawn and throughout the day until dusk, stopping sporadically to rest and chew their cud. Ideal pasture for sheep is not lawn-like grass, but an array of grasses, legumes and forbs.[2] 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 acorns, yew, rhododendrons, azaleas, all plants of the nightshade family, larkspur, lupine and many others. Sheep also may perish from consuming man-made substances. Sheep are unlike goats and deer, which are browsing animals that prefer weeds and taller foliage. With a much narrower face, it can crop plants very close to the ground and can overgraze a pasture much faster than cattle.[2] For this reason, most shepherds advocate some type of managed grazing whereby a flock is rotated through multiple pastures, giving plants time to recover.[7] [2] [5] [8] Other than forage, the only other common staple feed for sheep is hay, generally during the winter months. The ability to survive solely on pasture (even without hay) varies with breed, but all sheep are capable of doing so. Also included in most sheep's diets are minerals, either in a trace mix or in blocks. Naturally, a constant source potable water is also a fundamental requirement for sheep.
Sheep are one of the few large animals raised for meat today that has never been widely kept in an intensive confined animal feeding operation.[7] Though there is a growing movement advocating extensive, free range farming, the vast majority of cattle, pigs, and poultry are still produced at factory farms.[2] Only a few types of sheep are regularly given high-concentration grain feed. Many shepherds choose to "flush" ewes and rams during breeding; providing feed in key periods to increase fertility and birth weight. As 70% of a lamb's growth occurs in the last 5-6 weeks of gestation, ewes are also flushed during that period.[7] Other than flushing, only lambs and especially old, infirm sheep are commonly provided with supplemental grain.[7] Feed provided to sheep must be of a kind especially formulated for them, as most cattle, poultry, pig, and even some goat feeds contain lethal amounts of copper to sheep.[7] The same danger applies to mineral supplements such as salt licks. When changing a sheep's content or time of feeding, changes are generally made gradually so as not to disrupt the function of the rumen; sudden changes in a sheep's diet can cause potentially fatal conditions such as bloat.[2]
Health
Sheep may fall victim to chemical, pathogenic and physical means of sickness and injury. As prey animals, they tend to hide the exterior symptoms of illness. Throughout history, much of the money and labor of sheep husbandry has gone in to dealing with sheep ailments in order to avoid the heavy losses sustained from them. Shepherds in history often created remedies through experimentation on the farm. In some countries, sheep do not have the economic impact to necessitate clinical studies designed to approve drugs specifically for usage with sheep. In such instance, many shepherds resort to extralabel usage of drugs approved for other animals.[2] In the 21st century, a minority of shepherds have turned to alternative treatments such as homeopathy, acupuncture and even Traditional Chinese Medicine to treat sheep veterinary problems. Though sometimes met with skepticism, a few alternative treatments been shown to be effective in trials for some specific problems.[2] [7]
Many shepherds take a variety of preventative measures in order to ward off problems before they arrive. The first is to ensure that all sheep purchased for the initial flock and replacement animals are healthy to begin with. Many buyers avoid outlets, such as sale barns, which are known to be clearing houses for animals culled from healthy flocks as either sick or simply inferior.[2] This can also mean maintaining a closed flock, and quarantining new sheep for a month. Two fundamental preventative programs are maintaining good nutrition and stressing sheep as little as possible. Handling sheep in loud, erratic ways causes them to emit the cortisol, a stress hormone. Elevated amounts of cortisol can lead to a weakened immune system, thus making sheep far more vulnerable to disease.[7] Signs of stress in sheep include: excessive panting, teeth grinding, restless movement, wool eating, and wood chewing. Preventing the presence of harmful chemical agents is also an important part of a shepherd's work. Common culprits of poisoning include pesticide sprays, chemical fertilizer, motor oil, as well as radiator coolant and antifreeze (sheep find these last two sweet to the taste).[2]
A common form of preventative medication for sheep are vaccinations and treatments for parasites. Both external and internal parasites are the most prevalent malady in sheep, and their susceptibility to them is a primary impediment to certified organic sheep farming.[2] Various worms comprise the majority of internal parasites, which are ingested during grazing, incubate within the sheep, and are expelled through the digestive system. Oral parasite medicines known as drenches are given to a flock to treat worms, sometimes after a count of eggs within the sheep's feces has been taken to assess infestation levels. Afterwards, sheep may be moved to a new pasture to prevent ingesting the same parasites.[8] External sheep parasites include: sheep keds, Nose bots, and maggots. Keds are extremely similar to common fleas, in that they are blood-sucking parasites that cause general malnutrition and decreased productivity, but are not fatal. Maggots are those of the Bot fly, and cause the extremely destructive condition of flystrike. Flys lay their eggs in wounds or wet, manure-soiled wool, and when the maggots hatch they burrow in to a sheep's living flesh, eventually resulting in death if unchecked. In addition to other treatments, crutching (shearing wool from a sheep's rump) is a common preventative method. Nose bots are flies which 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 sprays or immersive treatments (i.e. sheep dips).[2]
A wide array of diseases caused by bacteria affect sheep, but a few are especially prevalent and some may even be transmittable to humans. 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 retard a sheep's ability to feed. Blue tongue disease is an insect-borne illness causing fever and inflammation of the mucous membranes. Soremouth is skin disease leaving lesions that is often transmitted to shepherds handling infected flocks. More seriously, the organisms that can spontaneous enzootic abortion in sheep are easily transmitted to pregnant women. Also of concern is scrapie and foot and mouth disease. Both effect sheep, and can cause the decimation of entire flocks. The latter poses a significant risk to humans. During the 2001 outbreak of foot and mouth disease, hundreds of sheep in the U.K. were culled, and some rare British breeds were at risk for extinction from the pandemic.[2]
Behavior
Sheep are prey animals with a strong gregarious instinct, and a majority of sheep behavior can be defined in these terms.[2] When sheep gather in larger social groups, it allows some sheep to concentrate on feeding and social interaction while others keep watch for a threat. All sheep exhibit some degree of natural flocking behavior, varying with breed. In regions such as Iceland, where sheep have no natural predators, none of the various breeds of sheep exhibit a strong flocking behavior, and tend to scatter rather than stay together when threatened in a similar manner to goats. The flocking characteristic is exploited by farmers often by the use of sheepdogs, as well as livestock guardian dogs. Whereas sheepdogs herd sheep, guardian dogs are trained to integrate in to flocks and protect them from predators. Other animals regularly used to protect sheep include donkeys and llamas, using the same basic principle. Sheep can also become hefted to one particular pasture so they do not roam. This is in particular a characteristic of English upland breeds. Ewes teach this behavior to their lambs, and if flocks are culled entirely it must be retaught to them.[10] [2]
Flock dynamics in sheep are as a rule only exhibited in a group of four or more sheep. Less sheep may not react as normally expected when alone or with very few other sheep. This is one reason why three is the usual number of sheep in a sheepdog trial, as it places the greatest pressure on a dog's herding abilities.[7] For sheep, the primary defense mechanism is simply to flee from danger when their flight zone is crossed. Secondarily, cornered sheep may attempt to leap at and ram threats in order to escape. This particularly true for ewes with newborn lambs and rams (hence the verb form of the word ram). 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 troughs. Relationships in flocks tend to be closest among related sheep: in mixed-breed flocks same-breed subgroups tend to form, and an ewe and her direct descendants often move as a unit within very large flocks.[7]
Sheep are frequently thought of as stupid animals that are the least trainable of all large livestock.[5] [2] 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 monograph on sheep found them to be just below pigs and on par with cattle in IQ, and some sheep have shown problem-solving abilities; a flock in Yorkshire, England found a way to get over cattle grids by rolling on their backs.[11] If worked with patiently sheep may learn their names, and many sheep are trained to be led by halter for showing and other purposes.[7] Very rarely, sheep are used as pack animals. Tibetan nomads distribute baggage equally throughout a flock as it is herded between living sites.[7]
Breeding behavior
The majority of sheep are seasonal breeders, though some are able to breed (also called tupping) year-round. Sheep generally reach sexual maturity at six to eight months of age, though ram lambs have occasionally been known to impregnate their mothers at two months. Ewes enter in to estrus cycles about every 17 days. In addition to emitting scent, they indicate their readiness through physical displays towards rams. Without human intervention, rams fight during the rut to determine which individuals may mate with ewes. During the rut, even normally friendly rams may become dangerous to humans. In some cases, especially aggressive rams may even be blindfolded or hobbled when interaction with people is necessary. A single healthy ram may impregnate up to 75 ewes in a single season. Sheep may sometimes display a preference for homosexuality, and the behavior occurs in about eight percent of rams on average.[12] Its occurrence does not seem to be related to dominance or flock hierarchy, rather the ram's typical motor pattern for intercourse is merely directed at rams instead of ewes.[12] After mating, sheep have a gestation period of around five months. Though some breeds may throw large litters of lambs, most produce either single or twin lambs.[2]
Methods of flock management
Generally speaking, there are four styles of sheep husbandry to serve the varied aspects of the sheep industry and the needs of a particular shepherd. Commercial sheep operations supplying meat and wool are usually either "range band flocks" or "farm flocks".[5] Range band flocks are those with large numbers of sheep (often 1,000-1,500 ewes) cared for by a few full-time shepherds. The pasture-which must be of large acreage to accommodate the greater number of sheep-can either be fenced or open. Range flocks usually require the shepherds to live with the sheep as they move throughout the pasture, as well as the use of sheepdogs and means of transport such as horses or motor vehicles.[1] As range band flocks move within a large area in which it would be difficult to supply a steady source of grain, almost all subsist on pasture alone.[5] This style of sheep raising accounts for the majority of sheep operations in the U.S., South America, and Australia.[1]
Farm flocks are those which are slightly smaller than range bands, and are kept on a more confined, fenced pasture land. Farm flocks may also be a secondary priority on a larger farm, such as by farmers who raise a surplus of crops to finish market lambs on, or those with untillable land they wish to exploit. However, farm flocks account for many farms focused on sheep as primary income in the U.K. and New Zealand (due to the more limited land available in comparison to other sheep-producing nations).[5] The farm flock is a common style of flock management for those who wish to supplement grain feed for meat animals.[5]
An important corollary form of flock management to the aforementioned styles are specialized flocks raising purebred sheep. Many commercial flocks, especially those producing sheep meat, utilize cross-bred animals.[8] Shepherds raising purebred flocks provide pedigreed breeding stock to these operations, and often simultaneously work to improve the breed and participate in showing. Excess lambs are often sold to 4-H groups. The last type of sheep keeping is that of the hobbyist. This type of flock is usually very small compared to commercial operations, and may be considered pets.[7] Those hobby flocks which are raised with production in mind may be for subsistence purposes or to provide a very specialized product, such as wool for handspinners. Quite a few shepherds, especially those who emigrated to rural areas from urban or suburban enclaves, begin with hobby flocks or a 4-H lamb before eventually expanding to farm or range flocks.[5]
History
Sheep were among the first animals to be domesticated by mankind, with sources providing a domestication date between nine and eleven thousand years ago in Mesopotamia.[13] [7] [1] [2] Determining the exact genetic ancestry of domestic sheep is a complex problem, and no particular lineage has received complete acceptance in the scientific community. The most common theory currently supported by DNA analysis indicates that Ovis aries is jointly descended from both the European (O. musimon) and Asiatic (O. orientalis) species of mouflon. It has also been proposed that the European mouflon is an ancient breed of domestic sheep turned feral rather than an ancestor, the lack of a fossil record for the species may support this hypothesis.[1] The urial (O. vignei) was once often thought to have been a forebear of domestic sheep; they occasionally interbreed with mouflon in the Iranian part of their range.[1] However, both the urial, argali (O. ammon), and snow sheep (O. nivicola) possess a different number of chromosomes than other Ovis species, making any direct influence highly implausible. Contemporary evaluations of sheep DNA show no evidence of urial ancestry.[14] Further DNA analysis comparing European and Asian breeds of sheep shows a significant percentage of genetic variance between the two. Two explanations for this phenomenon have been posited. The first is that there is a currently unknown species or subspecies of wild sheep that contributed to the formation of domestic sheep.[15] A second theory suggests that this variation is the result of multiple waves of capture from wild mouflon, similar to the known development of other livestock.[16]
Initially, sheep were kept solely for meat, milk and skins. Archaeological evidence from statuary found at sites in Iran suggests that selection for wooly sheep may have began circa 6000 BC, but the earliest woven wool garments have only been dated to two to three thousand years later.[5] By that span of the Bronze Age, sheep with all the major features of modern breeds were widespread throughout Western Asia.[1] However, one chief difference between ancient sheep and most modern breeds is the technique by which wool could be collected. Primitive sheep cannot be sheared, but must have their wool plucked out by hand in a process called '"rooing". This is due to the fact that their kemps (coarse, unworkable hairs) 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. Originally, weaving and spinning wool was a handicraft practiced at home, rather than an industry. Egyptians, Babylonians, Sumerians, and Persians all depended on sheep; and though 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.[1]
In Europe
From the Near East, sheep husbandry spread quickly in to Europe. Practically from it's inception, ancient Greek civilization relied on sheep as primary livestock, and were even said to name individual animals.[7] Scandanavian sheep of a type seen today — with short tails and multi-colored fleece — were also present early on. Later, the Roman Empire kept sheep on a wide scale, and the Romans were an important agent in the spread of sheep raising throughout the continent. Romans also pioneered the practice of blanketing sheep, in which a fitted coat (today usually of nylon) is placed over the sheep to improve the cleanliness and luster of its wool.[1] During the Roman occupation of the British Isles, a large wool processing factory was established in Winchester, England circa 50 AD.[7] Beginning in 1000 AD, England and Spain were recognized as the epicenters of sheep production in the Western world, and the word "sheep" itself was first used in Middle English, the language of the period.[17] Etymologically the word is derived from the Old English term scēap, and it is akin to the Old High German scāf.[17] As the progenitors of the extremely fine-wooled Merino breeds, the Spanish gained great wealth; wool money largely financed Spanish rulers, and thus, the voyages to the New World.[1] [7] Exportation of Merinos was a punishable offense that required royal permission, thus ensuring a near-absolute monopoly on the breed until Napoleon's invasion of that country in the mid-Eighteenth century. The sole substantial flock of Merinos to escape the Spanish edict was one exported to Rambouillet by Louis XVI in 1786, thus forming the basis for the modern Rambouillet (or French Merino) breed.[2]
The sheep industry in Spain was an instance of completely open range flock management, with enormous flocks of a only a few breeds ranging over the entire nation. However, the ovine model used in England was quite different, and had a similar importance to economy of the British Empire; to this day the Lord Speaker of the House of Lords sits on a bench known as the Woolsack. The high concentration and more sedentary nature of shepherding in the U.K. allowed sheep especially adapted to their particular purpose and region to be raised, thereby giving rise to an exceptional variety of breeds in relation to the land mass of the country.[1] This greater variety of breeds also produced a valuable variety of products to compete with the superfine wool of Spanish sheep. The growth of the sheep industry in Britain quickened in the 15th and 16th centuries due to booming wool prices and the greater pasture available due to a diminished population (the result of the Black Death). More landholders were willing and able to turn their lands over to pasture for sheep, and an influx of Flemish immigrants skilled in cloth making and dyeing during the reign of Edward III helped to cement the wool trade. By this time, Britain began moving from an open field system to one of enclosure. The unilateral closing of commons by landed gentry had enormously detrimental effects on local communities — entire villages were sometimes depopulated to make way for pasture — and was widely protested.[18] By the time of Elizabeth I's rule, sheep and wool trade was the primary source of tax revenue to the Crown of England.[1] An important event not only in the history of domestic sheep, but of all livestock, was the work of Robert Bakewell in the 1700's. Before his time, breeding for desirable traits was a often based on chance, with no scientific process for selection of breeding stock. Bakewell established the principles of selective breeding — especially line breeding — in his work with sheep, horses and cattle, and his theories were an influence on the subsequent work of Gregor Mendel and Charles Darwin.[7] [2] His most important contribution to sheep was the development of the Leicester Longwool, a quick-maturing breed of blocky confirmation that formed the basis for many vital modern breeds.[2] Today, the sheep industry in Spain and the U.K. does not play as large an international role, even if it is often of local economic and cultural importance; both countries are still large consumers of sheep meat.
In the Americas
No ovine species native to the Americas has ever been domesticated, despite the fact that they are closer genetically to domestic sheep than many Asian and European species, having the same number of chromosomes. The first domestic sheep — most likely of the Churra breed — in arrived with Christopher Columbus' second voyage in 1493.[1] [7] The next Transatlantic shipment to arrive was with Hernán Cortés in 1519, landing in Mexico.[1] Neither of these established a substantial population of sheep, and no export of wool or animals is known to have occurred. The next transport of sheep to North America was not until 1607 with the voyage of the HMS Susan Conant to Virginia.[1] However, the sheep that arrived in that year were all consumed because of a famine, and a permanent flock was not to reach the colony until two years later in 1609.[5] Two decades later, the colonists had grown their flock to a total of 400. Sheep were also eventually purchased from the Dutch colonizers of Manhattan. In 1662, a woolen mill was built in Watertown, Massachusetts, and by the 1640's there were approximately 100,000 head of sheep in the thirteen colonies.[1] [7] Early on, the British government banned further export of sheep to the Americas, or wool from it, in an attempt to stifle any threat to the wool trade in the British Isles. One of many restrictive trade measures the precipitated the American Revolution, the sheep industry in the Northeast grew despite the bans.
Gradually throughout the 1900's, sheep production moved westward, and today the vast majority of flocks reside on Western range lands. During this westward migration of the industry, competition between sheep and cattle operations grew more heated, eventually erupting in to range wars. Other than simple competition for grazing and water rights, cattlemen believed that the secretions of the foot glands of sheep made cattle unwilling to graze on places where sheep had stepped.[5] Sheep production peaked in the United States during 1940's and 50's at more than 55 million head.[7] Henceforth and continuing today, the number of sheep in North America has steadily declined with wool prices and the lessening American demand for sheep meat.[2]
In South America, especially in Argentina, Chile, Brazil, Uruguay, and Peru, there is an active modern sheep industry. The most exceptional area of production is surrounding the La Plata river in the Pampas region, spanning Argentina and Uruguay. However, despite the prime conditions for flocks, sheep operations often find themselves in stiff competition from the immense cattle industry on the continent.[1]
In Australia and New Zealand
Australia and New Zealand are crucial players in the contemporary sheep industry, and sheep are an iconic part of both countries' culture and economy. New Zealand has the highest density of sheep per capita (sheep outnumber the human population 12–1), and currently Australia is the world's indisputably largest exporter of sheep and cattle.[19] Though sheep were present in these countries from the earliest stages of their colonization, the Merino breed — the cornerstone of the Australian sheep industry — was not introduced until 1789.[1] While much of the growth in both nations was due to the active support of Britain, both worked to develop many unique new high-production breeds: the Corriedale, Coopworth, Perendale, and most of the ten varieties of Merino were created in New Zealand or Australia.[2] Wool production was a fitting industry for colonies far from their home nations. Before the advent of fast air and maritime shipping, wool was one of the few viable products that was not subject to spoiling on the long passage back to British ports. Flocks in Australia have always been largely range bands on fenced land, and are aimed at production of superfine wool for clothing and other products as well as meat. New Zealand flocks are kept in a fashion similar to English ones, in fenced holdings without herders. Though wool was once the primary income source for New Zealand shepherds, today it has shifted to meat production.[1] [20]
Somewhat unusually for livestock, the Australian sheep industry is the only sector internationally to receive strident, widespread criticism for its practices. The custom of mulesing, in which flesh is cut away from an animal's perineal area without anesthesia to prevent cases of flystrike, has been condemned widely as painful and unnecessary.[21] In response, a program of phasing out mulesing is currently being implemented.[22]The majority of sheep meat exports from Australia are to two sources: frozen carcasses to the U.K. and live animals to the Middle East. Shipped on converted oil tankers in what has been called crowded, unsafe conditions by critics, live sheep are desired by Middle Eastern nations to meet the requirements ritual halal slaughter.[23] 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 within Australia to make export of live animals redundant.[23] A few celebrities and companies have pledged to boycott all Australian sheep products in protest.[24] [21]
Cultural significance
Sheep have had a strong presence within many cultures, especially in areas where they form the most common type of livestock. A wide symbology relates to sheep in art, religion and language. The raising of sheep for wool and meat became a major industry in the U.K. Australia and New Zealand and remains significant. As a result, sheep and sheep shearing have become an important part of the cultural traditions of these countries in particular. More ancient references to sheep usually revolve around their original region of domestication in Western Asia.
Sheep have become an integral part of many linguistic traditions. In the English language, to call someone a sheep or ovine may allude that they are timid and easily led, if not outright stupid.[17] In contradiction to this image, male sheep are often used as symbols of virility and power, such as for the St. Louis Rams and the Dodge Ram. Sheep are key symbols in nursery rhymes like Little Bo Peep, novels such as George Orwell's Animal Farm and Thomas Hardy's Far From the Madding Crowd, poems like as William Blake's "The Lamb", and songs such as Pink Floyd's "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". Stereotypically, sheep are proverbial for their willingness to follow others of their kind. Citizens who accept overbearing governments have been referred to by the portmanteau neologism of sheeple. Somewhat differently, the adjective "sheepish" is also used to describe embarrassment.[25]
In religion and folklore
Religious symbolism and ritual involving sheep began with some of the first recorded faiths. In Ancient Egyptian religion, the ram was the symbol of Heryshaf and Amun, the latter in his incarnation as a god of fertility.[7] Other deities shown with ram features include: the goddess Ishtar, the Phoenecian god Baal-Hamon, and the Babylonian god Ea-Oannes.[7] There are also many ancient Greek references to sheep. The god Pan was strongly associated with flocks and herds, and the legend of Chrysomallos the golden-fleeced ram continues to be told through the modern era, and is the central image of the chivalric Order of the Golden Fleece. Sheep play an important symbolic and historical part in all the Abrahamic faiths, since Abraham, Isaac, Jacob, Moses, and King David all worked as shepherds. According to the Biblical story of the Binding of Isaac, a ram is sacrificed as a substitute for Issac after an angel stays Abraham's hand. Eid ul-Adha is a major annual festival in Islam in which a sheep is sacrificed in remembrance of this act. Greeks and Romans also sacrificed sheep regularly in religious practice, and Judaism also once sacrificed sheep as part of Korban. Many ovine symbols — such as the Passover lamb and the ceremonial blowing of a shofar — still find a presence in modern Jewish traditions. In Christianity, a congregation is often referred to as a flock, and the Adoration of the shepherds is a key image in Christian iconography surrounding the birth of Jesus. 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. The ram is the first sign of the Western astrological zodiac, in which it is known as Aries. The sheep also forms one of the animals associated with the 12-year cycle of in the Chinese zodiac, related to the Chinese calendar. Chinese tradition associates each animal with certain personality attributes, and people born in the year of the sheep are said to be shy, mild-mannered, and artistic, among other traits.
Economic importance
| Global Sheep and Lamb stock | |
|---|---|
| in 2005 | |
| Number in millions | |
1.  People's Republic of China | 170.9 (15.84%) |
2.  Australia | 102.7 (9.52%) |
3.  European Union (15 nation) | 99.3 (9.2%) |
4.  Russia (former Soviet Union) | 65.3 (6.05%) |
5.  India | 62.5 (5.79%) |
6.  Iran | 54 (5%) |
7.  Sudan | 49 (4.54%) |
8.  New Zealand | 39.9 (3.7%) |
9.  United Kingdom | 35.3 (3.27%) |
10.  South Africa | 25.3 (2.34%) |
| World total | 1079.0 |
| Source: UN Food and Agriculture Organization | |
Domestic sheep have been important to many economies, given that sheep provide a wide array of raw materials. Wool continues to be a vital textile, though beginning in the late 20th century wool prices fell dramatically as the result of the popularity and cheap prices for synthetic fabrics.[7] For many shepherds, the cost of shearing is greater than the possible profit from the fleece, making subsisting on wool production alone practically impossible without farm subsidies.[7] Historically Wool has also been used as alternative material in making such products as building insulation. Sheepskin is likewise used for making clothes, footwear, rugs, and other products. The popularity of lamb and mutton as food varies by region, being a primary protein source in some nations and a luxury in others. Byproducts from the slaughter of sheep are also of value: sheep tallow was once used in candlemaking, sheep bone and cartilage has been used to furnish carved items such as dice and buttons as well as rendered glue and gelatin. Sheep intestine can be formed into sausage casings, and lamb intestine has especially been formed into surgical sutures, as well as strings for musical instruments and tennis rackets.[1] Sheep droppings have even been sterilized and mixed with other traditional pulp materials to make paper.[26] Of all sheep byproducts, perhaps the most valuable is lanolin: the water-proof, fatty substance found naturally in sheep's wool, and used as a base for innumerable cosmetics and other products.[1]
In the 21st century, sheep retain considerable importance in the economies of several countries. After China, the largest producers of sheep products are in the southern hemisphere: Australia, New Zealand and the Patagonian regions of Argentina, Uruguay, and Chile. Sheep play an important role in the economies of a number of smaller countries where the number of sheep may not be great and impact on the global economy is negligible, but is still very importantly locally. For example, sheep production in the Faroe Islands is of key importance to the local history and economy, but has no perceptible impact on the global sheep meat or wool trade.
As food
Sheep meat and milk were one of the earliest staple proteins consumed by human civilization after the transition from hunting and gathering to agriculture.[2] Chefs and diners commonly know sheep meat prepared for food as either lamb or mutton (which is etymologically very close to the French word for sheep: mouton). Technically, lamb is only the meat of young sheep under a year in age, and all other sheep meat is by definition mutton. In the 21st century, the nations with the highest consumption of sheep meat are the Persian Gulf states, New Zealand, Australia, Greece, Uruguay, the U.K. and Ireland.[7] These countries eat between 14 and 39 lbs. (approximately 3-18 kilos) of sheep meat per capita, per annum. By comparison, countries such as the U.S. consume only a pound or less. In addition, such countries rarely eat mutton, and may even restrict their habits to the more expensive cuts of lamb: mostly the chop and the leg.[7] In those that do favor sheep meat, it is often the product of a past history of sheep production, even if they produce little or no sheep today. In such countries in particular, dishes comprised of alternative cuts and offal may be popular or traditional. Sheep testicles – called animelles or Lamb fries in culinary terminology – are considered a delicacy in many parts of the world. Perhaps the most infamous dish of sheep meat is the Scottish haggis, comprised of a sheep's heart, liver and lungs cooked within its stomach.[2] [5]
Though it may have been in antiquity, today sheep's milk is no longer drank directly on any appreciable level. Sheep's milk is, however, valuable in the creation of some popular varieties of cheese and yogurts. Containing 6% fat and double the solids of cow's milk, it can be crafted in to such dairy products with relative ease. Well-known sheep milk cheeses include the Roquefort of France, the Brocciu of Corsica, Manchego from Spain, the Pecorino Romano of Italy and Feta of Greece. Sheep milk does contain 4.8% lactose, which may affect those who are intolerant.[7]
In science
Though not common model organisms, sheep have had played a small role, yet influential role in scientific experimentation. However, several of the few contemporary instances of sheep experimentation has caused a significant impact on science and culture at large. In 1996, a Finnish Dorset sheep named Dolly was the first mammal ever to be cloned from an adult somatic cell. Beginning in 2006, controversy raged over a scientific study at the Oregon Health and Science University which investigated the biological mechanisms producing homosexuality in rams. Organizations such as PETA actively campaigned against the study, accusing scientists of trying to cure homosexuality in the sheep.[12]
References
- ^ a b c d e f g h i j k l m n o p q r s t u v w Ensminger, Dr. M.E. (1986). Sheep and Goat Science, Fifth Edition. Danville, Illinois: The Interstate Printers and Publishers Inc. ISBN 0-8134-2464-X.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ a b c d e f g h i j k l m n o p q r s t u v w x y Simmons, Paula (2001). Storey's Guide to Raising Sheep. 210 MASS MoCA Way,North Adams, MA 01247: Storey Publishing LLC. ISBN 978-1-58017-262-2.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)CS1 maint: location (link) - ^ Melinda J. Burrill Ph.D. Professor Coordinator of Graduate Studies, Department of Animal and Veterinary Sciences, California State Polytechnic University (2004). "Sheep". World Book. Mackiev.
{{cite encyclopedia}}: CS1 maint: multiple names: authors list (link) - ^ Schoenian, Susan. "Sheep101.info". Retrieved 2007-11-27.
- ^ a b c d e f g h i j k l m n o p q r Smith M.S., Barbara (1997). Beginning Shepherd's Manual, Second Edition. Ames, Iowa: Iowa State University Press. ISBN 0-8138-2799-X.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help) - ^ Shulaw, Dr. William P. (2006). "Sheep Care Guide". Retrieved 2007-11-27.
{{cite journal}}: Cite journal requires|journal=(help) - ^ a b c d e f g h i j k l m n o p q r s t u v w x y z aa ab ac Weaver, Sue (2005). Sheep: small-scale sheep keeping for pleasure and profit. 3 Burroughs Irvine, CA 92618: Hobby Farm Press, an imprint of BowTie Press, a division of BowTie Inc. ISBN 1-931993-49-1.
{{cite book}}: Cite has empty unknown parameter:|coauthors=(help)CS1 maint: location (link) - ^ a b c d e f Brown, Dave (1996). The Modern Shepherd. Wharfedale Road, Ipswich 1P1 4LG, UNited Kingdom: Farming Press. ISBN 0-85236-188-2.
{{cite book}}: Unknown parameter|coauthors=ignored (|author=suggested) (help)CS1 maint: location (link) - ^ "Sheep (Ovis aries)". Breeds of Livestock. Oklahoma State University Dept. of Animal Science. Retrieved 2007-11-2.
{{cite web}}: Check date values in:|accessdate=(help) - ^ "Sheep taught to stay put". BBC News. 3 November, 2001. Retrieved 2006-04-29.
{{cite web}}: Check date values in:|year=(help)CS1 maint: year (link) - ^ "Crafty sheep conquer cattle grids". BBC News. 30 July, 2004. Retrieved 2006-04-29.
{{cite web}}: Check date values in:|year=(help)CS1 maint: year (link) - ^ a b c Schwartz, John (January 25, 2007). "Of Gay Sheep, Modern Science and Bad Publicity". The New York Times. Retrieved 2007-12-07.
- ^ Krebs, Robert E. & Krebs, Carolyn A (2003). Groundbreaking Scientific Experiments, Inventions & Discoveries of the Ancient World. Westport, CT: Greenwood Press. ISBN 0-313-31342-3.
{{cite book}}: CS1 maint: multiple names: authors list (link) - ^ Hiendleder S, Kaupe B, Wassmuth R, Janke A. (2002). "Molecular analysis of wild and domestic sheep questions current nomenclature and provides evidence for domestication from two different subspecies". Proceedings, Biological sciences, The Royal Society of London.
{{cite web}}: Unknown parameter|accessmonthday=ignored (help); Unknown parameter|accessyear=ignored (|access-date=suggested) (help); Unknown parameter|month=ignored (help)CS1 maint: multiple names: authors list (link) - ^ "Analysis of mitochondrial DNA indicates that domestic sheep are derived from two different ancestral maternal sources: no evidence for contributions from urial and argali sheep". The Journal of Heredity. 89 (2): 113. 2007. 9542158. Retrieved 2007-11-29.
Our data supports the hypothesis that some modern domestic sheep and European mouflon derive from a common ancestor and provide evidence of an additional wild ancestor, other than the urial and argali groups, which has yet to be identified.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ "Five ovine mitochondrial lineages identified from sheep breeds of the near East". Genetics. 175 (3): 1371. 2007. 17194773. Retrieved 2007-11-29.
The identification in this study of evidence for additional domestication events adds to the emerging view that sheep were recruited from wild populations multiple times in the same way as for other livestock species such as goat, cattle, and pig.
{{cite journal}}: Unknown parameter|coauthors=ignored (|author=suggested) (help); Unknown parameter|month=ignored (help) - ^ a b c "Sheep". Merriam-Webster's Online Dictionary. Retrieved 2007-12-01.
- ^ Thirsk, Joan (2000). The Agrarian History of England and Wales. Cambridge University
Press. ISBN v=0521200741.
{{cite book}}: Check|isbn=value: invalid character (help); Unknown parameter|coauthors=ignored (|author=suggested) (help); line feed character in|publisher=at position 21 (help) - ^ "The people of New Zealand". TeAra: the Encyclopedia of New Zealand. 09 June, 2006. Retrieved 2007-12-07.
{{cite web}}: Check date values in:|year=(help)CS1 maint: year (link) - ^ "Agricultural production". TeAra: the Encyclopedia of New Zealand. 2007. Retrieved 2007-12-07.
- ^ a b "Wool Boycott Targets Australia Sheep Farmers". National Geographic News. August 16, 2005. Retrieved 2007-12-07.
- ^ Peter Wilkinson (8 November,2004). "In the News". Australian Wool Growers Association. Retrieved 2007-01-09.
{{cite web}}: Check date values in:|date=(help) - ^ a b "Savethesheep.com". PETA. Retrieved 2007-12-07.
- ^ "Pink angers Australian government". BBC News. 20 December 2006. Retrieved 2007-01-09.
- ^ "Sheepish". Merriam-Webster's Online Dictionary. Retrieved 2007-12-01.
- ^ "Sheeppoopaper.com". Retrieved 2007-12-01.
External links
- Template:Dmoz
- Sheep101.info
- A Glossary of sheep terms from the American Sheep Industry Association
- The Domestic Sheep by Henry Stewart (1898), "Natural History" and "Anatomy."