Milk and dairy products

After lambs are several weeks old, lamb marking--the process of ear tagging, docking, and castrating--is carried out. 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. Ram lambs that will either be slaughtered or separated from ewes before sexual maturity are not usually castrated. Docking, which is the shortening of a lamb's tail, is practised for health reasons. 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.

Health

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. However, there are some obvious signs of ill health, with sick sheep eating little, vocalizing excessively, and being generally listless. 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. In such instances, shepherds resort to illegal, extra-label usage of drugs approved for other animals. 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. Despite some favorable anecdotal evidence, the effectiveness of alternative veterinary medicine has been met with skepticism in scientific journals. The need for traditional anti-parasite drugs and antibiotics is widespread, and is the main impediment to certified organic farming with sheep.

Many breeders take a variety of 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. This can also mean maintaining a closed flock, and 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. Signs of stress in sheep include: excessive panting, teeth grinding, restless movement, wool eating, and wood chewing. 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).

Common forms of preventive medication for sheep are vaccinations 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. Worms 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 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. External sheep parasites include: lice (for different parts of the body), sheep keds, nose bots, sheep itch mite, and maggots. 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 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 backliners, sprays or immersive sheep dips.

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

A few sheep conditions are transmittable to humans. 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.

Predation

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. 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. In contrast, other nations are virtually devoid of sheep predators, particularly islands known for extensive sheep husbandry. Worldwide, canids --including the domestic dog--are responsible for most sheep deaths. Other animals that occasionally prey on sheep include: felines, bears, birds of prey, ravens and feral hogs.

Sheep producers have used a wide variety of measures to combat predation. Pre-modern shepherds used their own presence, livestock guardian dogs, and protective structures such as barns and fencing. Fencing (both regular and electric), penning sheep at night and lambing indoors all continue to be widely used. More modern shepherds used guns, traps, and poisons to kill predators, 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, rather than sheep producers.

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.Donkeys and guard llamas have been used since the 1980s in sheep operations, using the same basic principle as livestock guardian dogs. 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. In addition to animal guardians, contemporary sheep operations may use non-lethal predator deterrents such as motion-activated lights and noisy alarms.

History

Sheep were among the first animals to be domesticated by mankind; sources provide a domestication date between nine and eleven thousand years ago in Mesopotamia. Their wild relatives have several characteristics--such as a relative lack of aggression, a manageable size, early sexual maturity, a social nature, and high reproduction rates--which made them particularly suitable for domestication. Today, Ovis aries is an entirely domesticated animal that is largely dependent on man for its health and survival. Feral sheep do exist, but exclusively in areas devoid of large predators (usually islands) and not on the scale of feral horses, goats, pigs, or dogs, although some feral populations have remained isolated long enough to be recognized as distinct breeds.

The exact line of descent between domestic sheep to their wild ancestors is presently unclear. The most common hypothesis states that Ovis aries is jointly descended from 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. A few breeds of sheep, such as the Castlemilk Moorit from Scotland, were formed through crossbreeding with wild European mouflon. The urial (O. vignei) was once thought to have been a forebear of domestic sheep, as they occasionally interbreed with mouflon in the Iranian part of their range. However, the urial, argali (O. ammon), and snow sheep (O. nivicola) have a different number of chromosomes than other Ovis species, making a direct relationship implausible, and phylogenetic studies show no evidence of urial ancestry. Further studies comparing European and Asian breeds of sheep showed significant genetic differences 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. A second hypothesis suggests that this variation is the result of multiple waves of capture from wild mouflon, similar to the known development of other livestock.

Initially, sheep were kept solely for meat, milk and skins. 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. By that span of the Bronze Age, sheep with all the major features of modern breeds were widespread throughout Western Asia. However, one chief difference between ancient sheep and modern breeds is the technique by which wool could be collected. 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 practised 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.

Sheep entered the African continent not long after their domestication in western Asia. A minority of historians once posited a contentious African theory of origin for Ovis aries. This theory is based primarily on rock art interpretations, and osteological evidence from Barbary sheep. The first sheep entered North Africa via Sinai, and were present in ancient Egyptian society between eight and seven thousand years ago. Sheep have always been part of subsistence farming in Africa, but today the only country that keeps an influential number of commercial sheep is South Africa. 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.

From Southwest Asia, sheep husbandry spread quickly in to Europe. Practically from its inception, ancient Greek civilization relied on sheep as primary livestock, and were even said to name individual animals. Scandinavian 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. Pliny the Elder, in his Natural History (Naturalis Historia), speaks at length about sheep and wool. Declaring "Many thanks, too, do we owe to the sheep, both for appeasing the gods, and for giving us the use of its fleece.", he goes on to detail the breeds of ancient sheep and the many colors, lengths and qualities of wool. 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.

During the Roman occupation of the British Isles, a large wool processing factory was established in Winchester, England in about 50 AD. By 1000 AD, England and Spain were recognized as the twin centers of sheep production in the Western world. As the original breeders of the fine-wooled merino sheep that have historically dominated the wool trade, the Spanish gained great wealth. Wool money largely financed Spanish rulers and thus the voyages to the New World by conquistadors. The powerful Mesta (its full title was Honrado Concejo de la Mesta, the Honorable Council of the Mesta) was a corporation of sheep owners mostly drawn from Spain's wealthy merchants, Catholic clergy and nobility that controlled the merino flocks. By the 17th century, the Mesta held in upwards of two million head of merino sheep.

Mesta flocks followed a seasonal pattern of transhumance across Spain. In the spring, they left the winter pastures (invernaderos) in Extremadura and Andalusia to graze on their summer pastures (agostaderos) in Castile, returning again in the autumn. Spanish rulers eager to increase wool profits gave extensive legal rights to the Mesta, often to the detriment of local peasantry. The huge merino flocks had a lawful right of way for their migratory routes (caсadas). Towns and villages were obliged by law to let the flocks graze on their common land, and the Mesta had its own sheriffs that could summon offending individuals to its own tribunals.

Sheep are often identified by farmers by using a paint mark called a raddle.

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. After the Napoleonic Wars and the global distribution of the once-exclusive Spanish stocks of Merinos, sheep raising in Spain reverted to hardy coarse-wooled breeds such as the Churra, and was no longer of international economic significance.

The sheep industry in Spain was an instance of migratory flock management, with large homogenous flocks ranging over the entire nation. 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.

The high concentration and more sedentary nature of shepherding in the UK 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. This greater variety of breeds also produced a valuable variety of products to compete with the superfine wool of Spanish sheep. By the time of Elizabeth I's rule, sheep and wool trade was the primary source of tax revenue to the Crown of England and the country was a major influence in the development and spread of sheep husbandry.

An important event not only in the history of domestic sheep, but of all livestock, was the work of Robert Bakewell in the 1700s. 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 breeding - especially line breeding - in his work with sheep, horses and cattle; his work later influenced Gregor Mendel and Charles Darwin. His most important contribution to sheep was the development of the Leicester Longwool, a quick-maturing breed of blocky conformation that formed the basis for many vital modern breeds. Today, the sheep industry in the UK has diminished significantly, though pedigreed rams can still fetch around 100,000 Pounds sterling at auction.

In the Americas

Sheep grazing on the south lawn of the White House c. 1918

No ovine species native to the Americas has ever been domesticated, despite being closer genetically to domestic sheep than many Asian and European species. The first domestic sheep in North America--most likely of the Churra breed--arrived with Christopher Columbus' second voyage in 1493. The next transatlantic shipment to arrive was with Hernбn Cortйs in 1519, landing in Mexico. No export of wool or animals is known to have occurred from these populations, but flocks did disseminate throughout what is now Mexico and the Southwest United States with Spanish colonists. Churras were also introduced to the Navajo tribe of Native Americans, and became a key part of their livelihood and culture. The modern presence of the Navajo-Churro breed is a result of this heritage.

North America

The next transport of sheep to North America was not until 1607, with the voyage of the HMS Susan Conant to Virginia. However, the sheep that arrived in that year were all slaughtered because of a famine, and a permanent flock was not to reach the colony until two years later in 1609. In two decades time, the colonists had expanded their flock to a total of 400 head. By the 1640s there were about 100,000 head of sheep in the 13 colonies, and in 1662, a woolen mill was built in Watertown, Massachusetts. Especially during the periods of political unrest and civil war in Britain spanning the 1640s and 50s which disrupted maritime trade, the colonists found it pressing to produce wool for clothing. Many islands off the coast were cleared of predators and set aside for sheep: Nantucket, Long Island, Martha's Vineyard and small islands in Boston Harbor were notable examples. There remain some rare breeds of American sheep--such as the Hog Island sheep--that were the result of island flocks. Placing semi-feral sheep and goats on islands was common practice in colonization during this period.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 that precipitated the American Revolution, the sheep industry in the Northeast grew despite the bans.

Gradually, beginning in the 1800s, sheep production in the U.S. moved westward. 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 into 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. As sheep production centered on the U.S. western ranges, it became associated with other parts of Western culture, such as the rodeo. In modern America, a minor event in rodeos is mutton busting, in which children compete to see who can stay atop a sheep the longest before falling off. 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. Sheep production peaked in North America during 1940s and 50s at more than 55 million head. 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.

South America

In South America, especially in Patagonia, there is an active modern sheep industry. Sheep keeping was largely introduced through immigration to the continent by Spanish and British peoples, for whom sheep were a major industry during the period. South America has a large number of sheep, but the highest-producing nation (Brazil) kept only just over 15 million head in 2004, far fewer than most centers of sheep husbandry. The primary challenges to the sheep industry in South America are the phenomenal drop in wool prices in the late 20th century and the loss of habitat through logging and overgrazing. The most influential region internationally is that of Patagonia, which has been the first to rebound from the fall in wool prices. With few predators and almost no grazing competition (the only large native grazing mammal is the guanaco), the region is prime land for sheep raising. The most exceptional area of production is surrounding the La Plata river in the Pampas region. Sheep production in Patagonia peaked in 1952 at more than 21 million head, but has steadily fallen to fewer then ten today. Most operations focus on wool production for export from Merino and Corriedale sheep; the economic sustainability of wool flocks has fallen with the drop in prices, while the cattle industry continues to grow.

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 to 1), and Australia is the world's indisputably largest exporter of sheep and cattle. In 2007, New Zealand even declared 15 February their official National Lamb Day to celebrate the country's history of sheep production.

The First Fleet brought the initial population of 70 sheep from the Cape of Good Hope to Australia in 1788. The next shipment was of 30 sheep from Calcutta and Ireland in 1793. All of the early sheep brought to Australia were exclusively used for the dietary needs of the penal colonies. The beginnings of the Australian wool industry were due to the vision and efforts of Captain John Macarthur. At Macarthur's urging 16 Spanish merinos were imported in 1797, effectively beginning the Australian sheep industry. By 1801 Macarthur had 1,000 head of sheep, and in 1803 he exported 245 lbs (111 kg) of wool to England. Today, Macarthur is generally thought of as the father of the Australian sheep industry.

The growth of the sheep industry in Australia was explosive. In 1820, the continent held 100,000 sheep, a decade later it had one million. By 1840, New South Wales alone kept 4 million sheep; flock numbers grew to 13 million in a decade.[90] While much of the growth in both nations was due to the active support of Britain in its desire for wool, both worked independently to develop new high-production breeds: the Corriedale, Coolalee, Coopworth, Perendale, Polwarth, Booroola Merino, Peppin Merino, and Poll Merino were all created in New Zealand or Australia. 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. The abundant new land and milder winter weather of the region also aided the growth of the Australian and New Zealand sheep industries.

Flocks in Australia have always been largely range bands on fenced land, and are aimed at production of medium to 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 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.

Animal welfare concerns

The Australian sheep industry is the only sector of the industry to receive international criticism for its practices. 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. The practice of mulesing, in which skin is cut away from an animal's perineal area to prevent cases of the fatal condition flystrike, has been condemned by PETA as being painful and unnecessary. In response, a program of phasing out mulesing is currently being implemented, and some mulesing operations are being carried out with the use of anaesthetic. 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.

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 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. 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. A few celebrities and companies have pledged to boycott all Australian sheep products in protest.

Economic importance

Sheep are an important part of the global agricultural economy. However, their once-vital status has been largely replaced by other livestock species, especially the pig, chicken, and cow. China, Australia, India, and Iran have the largest modern flocks, and serve both local and exportation needs for wool and mutton. Other countries such as New Zealand have smaller flocks but retain a large international economic impact due to their export of sheep products. Sheep also play a major role in many local economies, which may be niche markets focused on organic or sustainable agriculture and local food customers. Especially in developing countries, such flocks may be a part of subsistence agriculture rather than a system of trade. Sheep themselves may be a medium of trade in barter economies.

Domestic sheep provide a wide array of raw materials. Wool was one of the first textiles, although in the late 20th century wool prices began to fall dramatically as the result of the popularity and cheap prices for synthetic fabrics. For many sheep owners, the cost of shearing is greater than the possible profit from the fleece, making subsisting on wool production alone practically impossible without farm subsidies. Fleeces are used as material in making alternative products such as wool insulation. In the 21st century, the sale of meat is the most profitable enterprise in the sheep industry, even though far less sheep meat is consumed than chicken, pork or beef.

Sheepskin is likewise used for making clothes, footwear, rugs, and other products. 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. Sheep intestine can be formed into sausage casings, and lamb intestine has been formed into surgical sutures, as well as strings for musical instruments and tennis rackets. Sheep droppings, which are high in cellulose, have even been sterilized and mixed with traditional pulp materials to make paper. 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.

Some farmers who keep sheep also make a profit from live sheep. Providing lambs for youth programs such as 4-H and competition at agricultural shows is often a dependable avenue for the sale of sheep. 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. 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.

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, such as that used in the intensive farming of chickens or pigs. They are an efficient use of land; roughly six sheep can be kept on the amount that would suffice for a single cow or horse. Sheep can also consume plants, such as noxious weeds, that most other animals will not touch, and produce more young at a faster rate. Also, in contrast to most livestock species, the cost of raising sheep is not necessarily tied to the price of feed crops such as grain, soybeans and corn. Combined with the lower cost of quality sheep, all these factors combine to equal a lower overhead for sheep producers, thus entailing a higher profitability potential for the small farmer. Sheep are especially beneficial for independent producers, including family farms with limited resources, as the sheep industry is one of the few types of animal agriculture that has not been vertically integrated by agribusiness.

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. Sheep meat prepared for food is known as either mutton or lamb. "Mutton" is derived from the Old French moton, which was the word for sheep used by the Anglo-Norman rulers of much of the British Isles in the Middle Ages. This became the name for sheep meat in English, while the Old English word sceap was kept for the live animal. Throughout modern history, "mutton" has been limited to the meat of mature sheep usually at least two years of age; "lamb" is used for that of immature sheep less than a year.

In the 21st century, the nations with the highest consumption of sheep meat are the Persian Gulf states, New Zealand, Australia, Greece, Uruguay, the United Kingdom and Ireland. These countries eat 14-40 lbs (3-18 kg) of sheep meat per capita, per annum. Sheep meat is also popular in France, Africa (especially the Maghreb), the Caribbean, the rest of the Middle East, India, and parts of China. This often reflects a past history of sheep production. In these countries in particular, dishes comprising alternative cuts and offal may be popular or traditional. Sheep testicles--called animelles or lamb fries--are 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. In comparison, countries such as the U.S. consume only a pound or less (under 0.5 kg), with Americans eating 50 pounds (22 kg) of pork and 65 pounds (29 kg) of beef. In addition, such countries rarely eat mutton, and may favor the more expensive cuts of lamb: mostly lamb chops and leg of lamb.

Though sheep's milk may have been drunk in antiquity, it today is used predominantly in cheese and yogurt. Sheep have only two teats, and produce a far smaller volume of milk than cows. However, as sheep's milk contains far more fat, solids, and minerals than cow's milk, it is ideal for the cheese-making process. It also resists contamination during cooling better because of its much higher calcium content. Well-known cheeses made from sheep milk include the Feta of Bulgaria and Greece, Roquefort of France, Manchego from Spain, the Pecorino Romano (the Italian word for sheep is pecore) and Ricotta of Italy. Yogurts, especially some forms of strained yogurt, may also be made from sheep milk. Many of these products are now often made with cow's milk, especially when produced outside their country of origin. Sheep milk contains 4.8% lactose, which may affect those who are intolerant.

In science. Sheep are generally too large and reproduce too slowly to make ideal research subjects, and thus are not a common model organism. 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 were the first mammals cloned from differentiated cells. 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, Mand a draft version of the complete genome produced by assembling sheep DNA sequences using information given by the genomes of other mammals.

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. 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. The feral Soays on Hirta are especially useful subjects because they are isolated.

Sheep are one of the few animals where the molecular basis of the diversity of male sexual preferences has been examined. 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. OHSU and the involved scientists vehemently denied such accusations.

Domestic sheep are sometimes used in medical research, particularly for researching cardiovascular physiology, in areas such as hypertension and heart failure. Pregnant sheep are also a useful model for human pregnancy, and have been used to investigate the effects on fetal development of malnutrition and hypoxia. In behavioral sciences, sheep have been used in isolated cases for the study of facial recognition, as their mental process of recognition is qualitatively similar to humans.

Cultural impact

Sheep have had a strong presence in many cultures, especially in areas where they form the most common type of livestock. In the English language, to call someone a sheep or ovine may allude that they are timid and easily led, if not outright stupid. 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 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 Three Bags Full: 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 kцnnen 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.

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. This usage derives from the recessive trait that causes an occasional black lamb to be born in to an entirely white flock. These black sheep were considered undesirable by shepherds, as black wool is not as commercially viable as white wool. 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.

In religion and folklore

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 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 Зatalhцyьk settlement in 8,000 BCE. In Ancient Egyptian religion, the ram was the symbol of several gods: Khnum, Heryshaf and Amun (in his incarnation as a god of fertility). Other deities occasionally shown with ram features include: the goddess Ishtar, the Phoenician god Baal-Hamon, and the Babylonian god Ea-Oannes. In Madagascar, sheep were not eaten as they were believed to be incarnations of the souls of ancestors.

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. 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. In Mongolia, shagai are an ancient form of dice made from the cuboid bones of sheep that are often used for fortunetelling purposes.

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. Sheep are also occasionally sacrificed to commemorate important secular events in Islamic cultures. Greeks and Romans also sacrificed sheep regularly in religious practice, and Judaism also once sacrificed sheep as a Korban (sacrifice), such as the Passover lamb. 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 Good Shepherd, and sheep are an element in the Christian iconography of the birth of Jesus. 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.

Молоко

Молоко - непрозрачная белая жидкость, млекопитающими. Оно является первичным источником пищи для новорожденных млекопитающих, когда они еще не могут переваривать другие виды пищи. Раннее молоко называется молозиво, оно передает антитела от к матери ребенку. Это уменьшает риск заболеваний у ребенка. Сырое молоко имеет различные компоненты, которые содержат существенное количество насыщенного жира, белка и кальция, а так же витамина C. Молоко коровы имеет кислотность pH в пределах от 6.4 до 6.8.

Типы потребления

Есть два основных типа потребления молока: естественный источник, который служит пищей для всех детенышей млекопитающих, и продукт питания для людей всех возрастов.

Пища для детенышей млекопитающих

Почти все млекопитающие кормят своих детенышей грудью, а также дают молоко, которое хранится и потребляется позже. Некоторые культуры в прошлом и в настоящее время продолжают использовать грудное молоко млекопитающих, чтобы кормить своих детей, по достижении 7-ми лет.

Продукт питания

Во многих культурах мира, особенно на Западе, люди продолжают потреблять молоко и в более позднем возрасте, используя молоко других животных (в частности коровы) как продукт питания. На протяжении веков молоко коровы перерабатывалось в молочные продукты, такие как сливки, масло, йогурт, кефир, мороженое и более длительный и легко транспортабельный продукт, сыр. Промышленность выработала казеин, белок сыворотки, лактозу, сгущенное молоко, сухое молоко, и много других видов продукции.

Многие людис возрастом не переносят молоко (то есть, они не воспринимают лактозу). Сахарная лактоза найдена в молоке, в некоторых цветах, ив нескольких видах тропических кустов. Фермент, необходимый для переваривания лактозы, находится в тонкой кишке с рождения, и с возрастом начинается медленное снижение его действия, если молоко не потреблять регулярно. С другой стороны, те, кто продолжают часто потреблять молоко, используют молоко одомашненных копытных животных, не только коров, но также и овец, коз, яков, индийского буйвола, лошадей, и верблюдов.

Как известно, молоко животных использовалось в качестве пищи с самого начала приручения животных. Впервые молоко коровы было использовано в качестве пищи на Ближнем Востоке. Козы и овцы были одомашнены на Ближнем Востоке между 9000 и 8000 г.г. до н.э. Козы и овцы приспособились, чтобы выжить на сухой траве, которая была их источником пищи, бесполезная для людей, но которую можно легко запасти. Животные сначала использовались на мясо, но производство молочных продуктов, оказалось более эффективным способом использования: питательная ценность животного, убитого на мясо, может быть сравнима с одной годовой ценностью молока от того же самого животного, которое будет продолжать давать молоко ежедневно в течение многих лет.

Приблизительно в 7000 до н.э, рогатый скот пасся в некоторой части Турции. Есть свидетельство об извлечении ДНК из скелетов с неолитического периода, что люди в Северной Европе испытывали недостаток генов для переработки лактозы. Ученые утверждают, более вероятно, что генетическая мутация, разрешающая переработкумолока, возникла после того, как появилось молочное животноводство, производство сыра и масла в Европе, части Азии и Африки. Молоко начали поставлять в бутылках с 11 января 1878 года. Этот день теперь помнят как День Молока и празднуют ежегодно. В городах Гарварде, Иллинойс также празднуют фестиваль молока, известный как День Молока.

На Западе сегодня коровье молоко производят в больших масштабах. Коммерческое использование молочного животноводства, с применением автоматизированного доильного оборудования привело к производству большого количества молока в развитых странах. Виды рогатого скота, типа Holstein, вывели для увеличенного производства молока. 90 % молочных коровв Соединенных Штатах и 85 %- в Великобритании - Holsteins. Другие виды молочных коров в Соединенных Штатах - это Ayrshire, Brown Swiss, Guernsey, Jersey, и Milking Shorthorn. Самые крупные производители молочных продуктов и молока сегодня - это Индия, Соединенные Штаты и Китай.

Сообщают, что в 2007 году, в связи с высоким международным процветанием и соревнованием по производству биологического топлива для промышленности цена на молоко существенно возрастает во всем мире. Особенно быстрое увеличение потребления молока происходит в Китае, а повышение цены на молоко в Соединенных Штатах.

Молоко - это эмульсия или коллоидная смесь капель молочного жира в воде. Каждая капля жира окружена мембраной, состоящей из фосфолипидов и белков; эти эмульгаторы не дают жировым каплям объединяться в зерна молочного жира, а также защищают капли, которые найдены в жидкой части молока, от деятельности ферментов переваривать жир. В негомогенизированном коровьем молоке, капли жира имеют в среднем размер четыре микрометра в диаметре. Растворимые в жирах витамины А, D, E, и K найдены в жировой части молока.

Самые большие структуры в жидкой части молока - мицеллы белка казеина - совокупность нескольких тысяч молекул белка, связанных с помощью частиц фосфата кальция. Каждая мицелла сферической формы и размером приблизительно одна десятая микрометра в диаметре. Есть четыре различных типа белков казеина, и все вместе они составляют приблизительно 80 процентов белка в молоке. Большинство белков казеина связано в мицеллы. Есть несколько конкурирующих теорий относительно точной структуры мицелл, но их объединяет одна важная особенность: наиболее удаленный слой состоит из одного типа белка -казеина, поступающего из тела мицеллы в ближайшую жидкость. Эти молекулы казеина имеют отрицательное электрический заряд, и поэтому отталкиваются друг друга, держа мицеллы.

И жировые капли, и маленькие мицеллы казеина, которые являются только достаточно большими, чтобы отклонить свет, что придает молоку непрозрачный белый цвет. Обезжиренное молоко, однако, кажется немного синим, потому что мицеллы казеина рассеивают более короткие длины волн.

Жировые капли содержат немного желто-оранжевого каротина, например, в молоке таких пород, какGuernsey и Jersey, это придает молоку золотой или "сливочный" оттенок. Рибофлавин в части сыворотки молока имеет зеленоватый цвет, который может иногда различаться в продуктах сыворотки или снятом молоке. Обезжиренное снятое молоко содержит только мицеллы казеина, которые рассеивают свет, при этом онирассеивают синий свет, который имеет более короткую длину волны, больше, чем красный свет, это придает молоку синеватый оттенок.

Молоко содержит множество других видов белка, кроме казеина. Они более растворимы в воде, чем казеин, и не формируют большие структуры. Эти белки остаются в сыворотке, когда происходит образование казеина при производстве творога, все вместе они называются белками сыворотки. Белки сыворотки составляют приблизительно 20% белка в молоке. Лактоглобуллин - общий белок сыворотки.

Углеводы лактозы придают молоку сладкий вкус и составляют около 40 % калорий в молоке коровы. Лактоза - это соединение простого сахара, глюкозы и галактозы. В природе, лактоза найдена только в молоке и в некоторых растениях. Железы, различные бактерии, и большое количество активных ферментов - это другие компоненты, находящиеся в молоке.

Обработка

В большинстве Западных стран, молочная промышленность перерабатывает молоко и производит молочные продукты, такие как сливки, масло, и сыр.

Пастеризация

Пастеризация используется, для уничтожения вредных микроорганизмов, молоко нагревается в течение короткого времени и затем охлаждается для хранения и транспортировки. Пастеризованное молоко является скоропортящимся продуктом, и его можно хранить с помощью холода для поставщиков и потребителей. На фермах печатают срок годности на каждом контейнере, после чего их складируют, иудаляют непроданное молоко с полок. Во многих странах незаконно продавать молоко, которое не пастеризовано.

Новый процесс - это стерилизация или ультравысокая температурная обработка (UHT), при которой молоко нагревают при более высокой температуре в течение более короткого времени. Это увеличивает его срок годности и позволяет хранить молоко неохлажденным благодаря длительному эффекту стерилизации.

После выдержки 12 - 24 часа в молоке отделяется слой сливок с высоким содержанием жира и обезжиренный слой молока. Сливки часто продаются как отдельный продукт с его собственным использованием; сегодня отделение сливок от молока обычно осуществляется в центробежных сепараторах. Жировые капли поднимаются к вершине контейнера молока, потому что жир менее плотный, чем вода. Чем меньше капли, тем больше молекулярных сил препятствует этому процессу.

Молоко подвергается гомогенизации - это обработка, которая препятствует слою сливок отделяться от молока. Молоко перекачивают при высоком давлении через очень узкие трубы, разбивая жировые капли посредством кавитации. Большое число маленьких частиц занимает большую область, чем меньшее число больших, и жировые капли мембран не могут полностью покрыть их.

Мицеллы казеина прилипают к жировым поверхностям; почти одна треть мицеллмолока не участвует в образовании новой мембранной структуры. Казеин превращается в капли и объединяется в кластеры, что ускоряет разделение. Жировые капли уязвимы для определенного вида ферментов молока, которые могут окислить жиры, и это вызывает прогорклый вкус молока. Чтобы это предотвратить, ферменты инактивируют с помощью пастеризации молока во время гомогенизации.