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91-554: Prominent veterinarians who have been members of the Australian Veterinary Association include Professor J.D. Stewart (who was the first AVA President), Ian Clunies Ross (former head of the CSIRO), and parasitologist Hugh Gordon . The AVA provides information resources, continuing education opportunities, publications, public education programs, and professional support. The AVA also lobbies government on

182-647: A diurnal pattern of activity, feeding from dawn to dusk, stopping sporadically to rest and chew their cud . Ideal pasture for sheep is not lawnlike grass, but an array of grasses , legumes and forbs . Types of land where sheep are raised vary widely, from pastures that are seeded and improved intentionally to rough, native lands. Common plants toxic to sheep are present in most of the world, and include (but are not limited to) cherry, some oaks and acorns, tomato, yew , rhubarb, potato, and rhododendron . Sheep are largely grazing herbivores, unlike browsing animals such as goats and deer that prefer taller foliage. With

273-418: A domesticated , ruminant mammal typically kept as livestock . Although the term sheep can apply to other species in the genus Ovis , in everyday usage it almost always refers to domesticated sheep. Like all ruminants, sheep are members of the order Artiodactyla , the even-toed ungulates . Numbering a little over one billion, domestic sheep are also the most numerous species of sheep. An adult female

364-670: A gestation period of about five months, and normal labor takes one to three hours. Although some breeds regularly throw larger litters of lambs, most produce single or twin lambs. During or soon after labor, ewes and lambs may be confined to small lambing jugs , small pens designed to aid both careful observation of ewes and to cement the bond between them and their lambs. Ovine obstetrics can be problematic. By selectively breeding ewes that produce multiple offspring with higher birth weights for generations, sheep producers have inadvertently caused some domestic sheep to have difficulty lambing; balancing ease of lambing with high productivity

455-472: A ewe and her direct descendants often move as a unit within large flocks. Sheep can become hefted to one particular local pasture (heft) so they do not roam freely in unfenced landscapes. Lambs learn the heft from ewes and if whole flocks are culled it must be retaught to the replacement animals. Flock behaviour in sheep is generally only exhibited in groups of four or more sheep; fewer sheep may not react as expected when alone or with few other sheep. Being

546-407: A few breeds that are predominantly used for milking. These sheep produce a higher quantity of milk and have slightly longer lactation curves. In the quality of their milk, the fat and protein content percentages of dairy sheep vary from non-dairy breeds, but lactose content does not. A last group of sheep breeds is that of fur or hair sheep , which do not grow wool at all. Hair sheep are similar to

637-475: A flock as it is herded between living sites. It has been reported that some sheep have apparently shown problem-solving abilities; a flock in West Yorkshire , England , allegedly found a way to get over cattle grids by rolling on their backs, although documentation of this has relied on anecdotal accounts. Sounds made by domestic sheep include bleats, grunts, rumbles and snorts. Bleating ("baaing")

728-479: A highly bred herding ability. Sheep are food-oriented, and association of humans with regular feeding often results in sheep soliciting people for food. Those who are moving sheep may exploit this behavior by leading sheep with buckets of feed. Sheep establish a dominance hierarchy through fighting, threats and competitiveness. Dominant animals are inclined to be more aggressive with other sheep, and usually feed first at troughs . Primarily among rams, horn size

819-783: A kingdom . He married Janet Leslie Carter on 6 October 1927, in Sydney, Australia. The couple had three sons, Anthony, Adrian and David. Clunies Ross was educated at Newington College (1912–1916) and in 1917 he entered the University of Sydney , in the Agriculture Faculty, and transferred to veterinary science at the beginning of 1918, graduating with second class honours in 1920. His father died in 1914, and his brothers Egerton and Rob died in WWI , killed in action and from pneumonic influenza respectively. In 1921, Clunies Ross

910-447: A month. Two fundamental preventive programs are maintaining good nutrition and reducing stress in the sheep. Restraint, isolation, loud noises, novel situations, pain, heat, extreme cold, fatigue and other stressors can lead to secretion of cortisol, a stress hormone, in amounts that may indicate welfare problems. Excessive stress can compromise the immune system. "Shipping fever" (pneumonic mannheimiosis, formerly called pasteurellosis)

1001-446: A much narrower face, sheep crop plants very close to the ground and can overgraze a pasture much faster than cattle. For this reason, many shepherds use managed intensive rotational grazing , where a flock is rotated through multiple pastures, giving plants time to recover. Paradoxically, sheep can both cause and solve the spread of invasive plant species . By disturbing the natural state of pasture, sheep and other livestock can pave

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1092-434: 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 mites , 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 , commonly Lucilia sericata or its relative L. cuprina . Fly maggots cause

1183-534: A number of fronts. Special interest groups have existed within the AVA since the early 1960s. These include groups dedicated to equine medicine, cattle, practice management, avian health, sheep, conservation and animal welfare. Some of the special interest groups publish their own peer reviewed journals. The Australian Veterinary History Society is a division of the association. Recent lobbying efforts include, HECS debt relief for rural veterinarians, mental health awareness in

1274-428: A prey species, a sheep's system is adapted to hide the obvious signs of illness, to prevent being targeted by predators. However, some signs of ill health are obvious, 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

1365-600: A prey species, the primary defense mechanism of sheep is to flee from danger when their flight zone is entered. Cornered sheep may charge and butt, or threaten by hoof stamping and adopting an aggressive posture. This is particularly true for ewes with newborn lambs. In regions where sheep have no natural predators, none of the native breeds of sheep exhibit a strong flocking behavior. Farmers exploit flocking behavior to keep sheep together on unfenced pastures such as hill farming , and to move them more easily. For this purpose shepherds may use herding dogs in this effort, with

1456-415: A result of selective breeding by humans. A few primitive breeds of sheep retain some of the characteristics of their wild cousins, such as short tails. Depending on breed, domestic sheep may have no horns at all (i.e. polled ), or horns in both sexes, or in males only. Most horned breeds have a single pair, but a few breeds may have several. Another trait unique to domestic sheep as compared to wild ovines

1547-476: A scent and indicate readiness through physical displays towards rams. In feral sheep, rams may fight during the rut to determine which individuals may mate with ewes. Rams, especially unfamiliar ones, will also fight outside the breeding period to establish dominance; rams can kill one another if allowed to mix freely. During the rut, even usually friendly rams may become aggressive towards humans due to increases in their hormone levels. After mating, sheep have

1638-505: A slow rate of growth. Long wool sheep are most valued for crossbreeding to improve the attributes of other sheep types. For example: the American Columbia breed was developed by crossing Lincoln rams (a long wool breed) with fine-wooled Rambouillet ewes. Coarse or carpet wool sheep are those with a medium to long length wool of characteristic coarseness. Breeds traditionally used for carpet wool show great variability, but

1729-819: A study published in Nature in 2001, Kenneth M. Kendrick and others reported; "Sheep recognize and are attracted to individual sheep and humans by their faces, as they possess similar specialized neural systems in the temporal and frontal lobes  ... individual sheep can remember 50 other different sheep faces for over 2 years". In addition to long-term facial recognition of individuals, sheep can also differentiate emotional states through facial characteristics. If worked with patiently, sheep may learn their names, and many sheep are trained to be led by halter for showing and other purposes. Sheep have also responded well to clicker training . Sheep have been used as pack animals; Tibetan nomads distribute baggage equally throughout

1820-422: A tendency to congregate close to other members of a flock, although this behavior varies with breed, and sheep can become stressed when separated from their flock members. During flocking, sheep have a strong tendency to follow, and a leader may simply be the first individual to move. Relationships in flocks tend to be closest among related sheep: in mixed-breed flocks, subgroups of the same breed tend to form, and

1911-429: A veterinary practice, lectured at the university and continued his own research on the hydatid parasite ( Echinococcus granulosus ), the liver fluke ( Fasciola hepatica ), and the dog-tick ( Ixodes holocyclus ). He developed an immunization for dogs to protect against the dog-tick. In 1926 Clunies Ross was appointed parasitologist to the newly established Council for Scientific and Industrial Research (CSIR), and

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2002-407: A waste product or a scent marker to help lost sheep find their flock, have also been proposed. Sheep and goats are closely related: both are in the subfamily Caprinae . However, they are separate species, so hybrids rarely occur and are always infertile. A hybrid of a ewe and a buck (a male goat) is called a sheep-goat hybrid , known as geep . Visual differences between sheep and goats include

2093-415: A well-focused retinal image of objects in both the middle and long distance. Because sheep eyes have no accommodation , one might expect the image of very near objects to be blurred, but a rather clear near image could be provided by the tapetum and large retinal image of the sheep's eye, and adequate close vision may occur at muzzle length. Good depth perception, inferred from the sheep's sure-footedness,

2184-496: Is hay , often during the winter months. The ability to thrive solely on pasture (even without hay) varies with breed, but all sheep can survive on this diet. Also included in some sheep's diets are minerals , either in a trace mix or in licks . Feed provided to sheep must be specially formulated, as most cattle, poultry, pig, and even some goat feeds contain levels of copper that are lethal to sheep. The same danger applies to mineral supplements such as salt licks . Sheep follow

2275-409: Is a dominant trait it spread quickly. However, colored sheep do appear in many modern breeds, and may even appear as a recessive trait in white flocks. While white wool is desirable for large commercial markets, there is a niche market for colored fleeces, mostly for handspinning . The nature of the fleece varies widely among the breeds, from dense and highly crimped, to long and hairlike. There

2366-581: Is a direct descendant of this population. Sheep were among the first animals to be domesticated by humankind (although the domestication of dogs probably took place 10 to 20 thousand years earlier); the domestication date is estimated to fall between 11,000 and 9000 BC in Mesopotamia and possibly around 7000 BC in Mehrgarh in the Indus Valley. The rearing of sheep for secondary products, and

2457-539: Is a disease of particular concern, that can occur as a result of stress, notably during transport and (or) handling. Pain, fear and several other stressors can cause secretion of epinephrine (adrenaline). Considerable epinephrine secretion in the final days before slaughter can adversely affect meat quality (by causing glycogenolysis, removing the substrate for normal post-slaughter acidification of meat) and result in meat becoming more susceptible to colonization by spoilage bacteria. Because of such issues, low-stress handling

2548-493: Is a factor in the flock hierarchy. Rams with different size horns may be less inclined to fight to establish the dominance order, while rams with similarly sized horns are more so. Merinos have an almost linear hierarchy whereas there is a less rigid structure in Border Leicesters when a competitive feeding situation arises. In sheep, position in a moving flock is highly correlated with social dominance, but there

2639-499: Is a highly contagious and often fatal viral disease affecting sheep and goats. Sheep may also be affected by primary or secondary photosensitization. Tetanus can also afflict sheep through wounds from shearing , docking , castration , or vaccination. The organism also can be introduced into the reproductive tract by unsanitary humans who assist ewes during lambing. A few sheep conditions are transmissible to humans. Orf (also known as scabby mouth, contagious ecthyma or soremouth)

2730-476: Is a skin disease leaving lesions that is transmitted through skin-to-skin contact. Cutaneous anthrax is also called woolsorter's disease, as the spores can be transmitted in unwashed wool. More seriously, the organisms that can cause spontaneous enzootic abortion in sheep are easily transmitted to pregnant women. Also of concern are the prion disease scrapie and the virus that causes foot-and-mouth disease (FMD), as both can devastate flocks. The latter poses

2821-742: Is buried in Box Hill cemetery. The career of Ian Clunies Ross is widely commemorated in Australia. The Australian $ 50 bank note issued in 1973 celebrated Ian Clunies Ross on one side, and Howard Florey on the other. The National Science Centre in Parkville, Victoria was renamed as Clunies Ross House in 1968, and decorated with a mural by Robert Ingpen celebrating Clunies Ross' career. Sheep Ovis guineensis Linnaeus, 1758 Ovis strepsiceros Linnaeus, 1758 Sheep ( pl. : sheep) or domestic sheep ( Ovis aries ) are

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2912-677: Is commonly given at an age of about 10 to 12 weeks; i.e. when the concentration of maternal antibodies passively acquired via colostrum is expected to have fallen low enough to permit development of active immunity. Ewes are often revaccinated annually about 3 weeks before lambing, to provide high antibody concentrations in colostrum during the first several hours after lambing. Ram lambs that will either be slaughtered or separated from ewes before sexual maturity are not usually castrated. Objections to all these procedures have been raised by animal rights groups, but farmers defend them by saying they save money, and inflict only temporary pain. Sheep are

3003-414: Is essential in sheep management. Avoiding poisoning is also important; common poisons are pesticide sprays, inorganic fertilizer , motor oil , as well as radiator coolant containing ethylene glycol. 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

3094-438: Is no definitive study to show consistent voluntary leadership by an individual sheep. Sheep are frequently thought of as unintelligent animals . Their flocking behavior and quickness to flee and panic can make shepherding a difficult endeavor for the uninitiated. Despite these perceptions, a University of Illinois monograph on sheep reported their intelligence to be just below that of pigs and on par with that of cattle. In

3185-477: Is one of the dilemmas of sheep breeding. In the case of any such problems, those present at lambing may assist the ewe by extracting or repositioning lambs. After the birth, ewes ideally break the amniotic sac (if it is not broken during labor), and begin licking clean the lamb. Most lambs will begin standing within an hour of birth. In normal situations, lambs nurse after standing, receiving vital colostrum milk. Lambs that either fail to nurse or are rejected by

3276-464: Is practised throughout the majority of the inhabited world, and has been fundamental to many civilizations. In the modern era, Australia , New Zealand , the southern and central South American nations, and the British Isles are most closely associated with sheep production. There is a large lexicon of unique terms for sheep husbandry which vary considerably by region and dialect . Use of

3367-483: Is referred to as a ewe ( / j uː / yoo ), an intact male as a ram , occasionally a tup , a castrated male as a wether , and a young sheep as a lamb . Sheep are most likely descended from the wild mouflon of Europe and Asia, with Iran being a geographic envelope of the domestication center. One of the earliest animals to be domesticated for agricultural purposes, sheep are raised for fleeces , meat ( lamb, hogget or mutton ), and milk . A sheep's wool

3458-523: Is the most widely used animal fiber, and is usually harvested by shearing . In Commonwealth countries, ovine meat is called lamb when from younger animals and mutton when from older ones; in the United States, meat from both older and younger animals is usually called lamb. Sheep continue to be important for wool and meat today, and are also occasionally raised for pelts , as dairy animals, or as model organisms for science. Sheep husbandry

3549-458: Is their wide variation in color. Wild sheep are largely variations of brown hues, and variation within species is extremely limited. Colors of domestic sheep range from pure white to dark chocolate brown, and even spotted or piebald . Sheep keepers also sometimes artificially paint "smit marks" onto their sheep in any pattern or color for identification. Selection for easily dyeable white fleeces began early in sheep domestication, and as white wool

3640-433: Is then passed into the rumen , via the reticulum . The rumen is a 19- to 38-liter (5 to 10 gallon) organ in which feed is fermented . The fermenting organisms include bacteria, fungi, and protozoa. (Other important rumen organisms include some archaea, which produce methane from carbon dioxide. ) The bolus is periodically regurgitated back to the mouth as cud for additional chewing and salivation . After fermentation in

3731-692: Is used mostly for contact communication, especially between dam and lambs, but also at times between other flock members. The bleats of individual sheep are distinctive, enabling the ewe and her lambs to recognize each other's vocalizations. Vocal communication between lambs and their dam declines to a very low level within several weeks after parturition. A variety of bleats may be heard, depending on sheep age and circumstances. Apart from contact communication, bleating may signal distress, frustration or impatience; however, sheep are usually silent when in pain. Isolation commonly prompts bleating by sheep. Pregnant ewes may grunt when in labor. Rumbling sounds are made by

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3822-489: Is variation of wool type and quality even among members of the same flock, so wool classing is a step in the commercial processing of the fibre. Depending on breed, sheep show a range of heights and weights. Their rate of growth and mature weight is a heritable trait that is often selected for in breeding. Ewes typically weigh between 45 and 100 kilograms (100 and 220 lb), and rams between 45 and 160 kilograms (100 and 350 lb). When all deciduous teeth have erupted,

3913-433: Is widespread, and is the main impediment to certified organic farming with sheep. Many breeders take a variety of preventive measures to ward off problems. The first is to ensure 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

4004-637: The Golden Fleece —and major religions, especially the Abrahamic traditions. In both ancient and modern religious ritual, sheep are used as sacrificial animals . The exact line of descent from wild ancestors to domestic sheep is unclear. The most common hypothesis states that Ovis aries is descended from the Asiatic ( O. gmelini ) species of mouflon ; the European mouflon ( Ovis aries musimon )

4095-606: The Neolithic period of prehistory, the Castelnovien people, living around Châteauneuf-les-Martigues near present-day Marseille in the south of France, were among the first in Europe to keep domestic sheep. Practically from its inception, ancient Greek civilization relied on sheep as primary livestock, and were even said to name individual animals. Ancient Romans kept sheep on a wide scale, and were an important agent in

4186-505: The dental formula for sheep is either 0.0.3.3 4.0.3.3 or 0.0.3.3 3.1.3.3 There is a large diastema between the incisors and the molars . In the first few years of life one can calculate the age of sheep from their front teeth, as a pair of milk teeth is replaced by larger adult teeth each year, the full set of eight adult front teeth being complete at about four years of age. The front teeth are then gradually lost as sheep age, making it harder for them to feed and hindering

4277-458: The rut , whereas rams do not. The domestic sheep is a multi-purpose animal, and the more than 200 breeds now in existence were created to serve these diverse purposes. Some sources give a count of a thousand or more breeds, but these numbers cannot be verified, according to some sources. However, several hundred breeds of sheep have been identified by the Food and Agriculture Organization of

4368-660: The topography for which the breed has been developed. This last point is especially stressed in the UK, where breeds are described as either upland (hill or mountain) or lowland breeds. A sheep may also be of a fat-tailed type , which is a dual-purpose sheep common in Africa and Asia with larger deposits of fat within and around its tail. Breeds are often categorized by the type of their wool. Fine wool breeds are those that have wool of great crimp and density, which are preferred for textiles. Most of these were derived from Merino sheep, and

4459-625: The "architect" of Australia's scientific boom, for his stewardship of the Commonwealth Scientific and Industrial Research Organisation ( CSIRO ), the Australian scientific organisation. Ian Clunies Ross was born in Bathurst, New South Wales on 22 February 1899. His grandfather, Robert Clunies Ross, was a brother of John Clunies-Ross , who settled with his family and crew on Cocos (Keeling) Islands in 1826-7 and proclaimed

4550-423: 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

4641-918: The Jacobson's organ) to sense the pheromones of ewes and detect when they are in estrus . The ewe uses her vomeronasal organ for early recognition of her neonate lamb. Sheep follow a similar reproductive strategy to other herd animals. A group of ewes is generally mated by a single ram, who has either been chosen by a breeder or (in feral populations) has established dominance through physical contest with other rams. Most sheep are seasonal breeders , although some are able to breed year-round. Ewes generally reach sexual maturity at six to eight months old, and rams generally at four to six months. However, there are exceptions. For example, Finnsheep ewe lambs may reach puberty as early as 3 to 4 months, and Merino ewes sometimes reach puberty at 18 to 20 months. Ewes have estrus cycles about every 17 days, during which they emit

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4732-597: The UN (FAO), with the estimated number varying somewhat from time to time: e.g. 863 breeds as of 1993, 1314 breeds as of 1995 and 1229 breeds as of 2006. (These numbers exclude extinct breeds, which are also tallied by the FAO.) For the purpose of such tallies, the FAO definition of a breed is "either a subspecific group of domestic livestock with definable and identifiable external characteristics that enable it to be separated by visual appraisal from other similarly defined groups within

4823-449: The basis of these tendencies. The dominance hierarchy of sheep and their natural inclination to follow a leader to new pastures were the pivotal factors in sheep being one of the first domesticated livestock species. Furthermore, in contrast to the red deer and gazelle (two other ungulates of primary importance to meat production in prehistoric times), sheep do not defend territories although they do form home ranges . All sheep have

4914-418: The beard of goats and divided upper lip of sheep. Sheep tails also hang down, even when short or docked , while the short tails of goats are held upwards. Also, sheep breeds are often naturally polled (either in both sexes or just in the female), while naturally polled goats are rare (though many are polled artificially). Males of the two species differ in that buck goats acquire a unique and strong odor during

5005-460: The breed continues to dominate the world sheep industry. Downs breeds have wool between the extremes, and are typically fast-growing meat and ram breeds with dark faces. Some major medium wool breeds, such as the Corriedale , are dual-purpose crosses of long and fine-wooled breeds and were created for high-production commercial flocks. Long wool breeds are the largest of sheep, with long wool and

5096-499: The chief requirement is a wool that will not break down under heavy use (as would that of the finer breeds). As the demand for carpet-quality wool declines, some breeders of this type of sheep are attempting to use a few of these traditional breeds for alternative purposes. Others have always been primarily meat-class sheep. A minor class of sheep are the dairy breeds. Dual-purpose breeds that may primarily be meat or wool sheep are often used secondarily as milking animals, but there are

5187-399: The decline of localized family farms , many breeds of sheep are in danger of extinction. The Rare Breeds Survival Trust of the UK lists 22 native breeds as having only 3,000 registered animals (each), and The Livestock Conservancy lists 14 as either "critical" or "threatened". Preferences for breeds with uniform characteristics and fast growth have pushed heritage (or heirloom) breeds to

5278-476: The early domesticated sheep kept before woolly breeds were developed, and are raised for meat and pelts. Some modern breeds of hair sheep, such as the Dorper , result from crosses between wool and hair breeds. For meat and hide producers, hair sheep are cheaper to keep, as they do not need shearing. Hair sheep are also more resistant to parasites and hot weather. With the modern rise of corporate agribusiness and

5369-771: The end of the war he left the university to assist the CSIR in planning sheep and wool -textile research. In 1946 he was appointed a full-time member of the CSIR Executive Committee, which was situated in Melbourne . He served as the executive officer of the CSIR until 1949 when it was renamed the CSIRO. He was chairman of the CSIRO until his death in 1959. During this time he oversaw the release of myxomatosis for rabbit control in Australia . In his retirement he

5460-728: The ewe require help to survive, such as bottle-feeding or fostering by another ewe. Most lambs begin life being born outdoors. After lambs are several weeks old, lamb marking ( ear tagging , docking , mulesing , 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. Docking and castration are commonly done after 24 hours (to avoid interference with maternal bonding and consumption of colostrum) and are often done not later than one week after birth, to minimize pain, stress, recovery time and complications. The first course of vaccinations (commonly anti-clostridial)

5551-403: 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 preventive method. Some countries allow mulesing , a practice that involves stripping away the skin on

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5642-418: The face, and some have facial wool (if any) confined to the poll and or the area of the mandibular angle; the wide angles of peripheral vision apply to these breeds. A few breeds tend to have considerable wool on the face; for some individuals of these breeds, peripheral vision may be greatly reduced by "wool blindness", unless recently shorn about the face. Sheep have poor depth perception ; shadows and dips in

5733-550: The farm. In some developed countries, including the United States, sheep lack the economic importance for drug companies to perform expensive clinical trials required to approve more than a relatively limited number of drugs for ovine use. However, extra-label drug use in sheep production is permitted in many jurisdictions, subject to certain restrictions. In the US, for example, regulations governing extra-label drug use in animals are found in 21 CFR (Code of Federal Regulations) Part 530. In

5824-529: The ground may cause sheep to baulk. In general, sheep have a tendency to move out of the dark and into well-lit areas, and prefer to move uphill when disturbed. Sheep also have an excellent sense of smell, and, like all species of their genus, have scent glands just in front of the eyes, and interdigitally on the feet. The purpose of these glands is uncertain, but those on the face may be used in breeding behaviors. The foot glands might also be related to reproduction, but alternative functions, such as secretion of

5915-537: The health and productivity of the animal. For this reason, domestic sheep on normal pasture begin to slowly decline from four years on, and the life expectancy of a sheep is 10 to 12 years, though some sheep may live as long as 20 years. Sheep have good hearing, and are sensitive to noise when being handled. Sheep have horizontal slit-shaped pupils, with excellent peripheral vision ; with visual fields of about 270° to 320°, sheep can see behind themselves without turning their heads. Many breeds have only short hair on

6006-451: The hoof, such as foot rot and foot scald may occur, and are treated with footbaths and other remedies. Foot rot is present in over 97% of flocks in the UK. 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 )

6097-429: The margins of the sheep industry. Those that remain are maintained through the efforts of conservation organizations, breed registries, and individual farmers dedicated to their preservation. Sheep are herbivorous . Most breeds prefer to graze on grass and other short roughage , avoiding the taller woody parts of plants that goats readily consume. Both sheep and goats use their lips and tongues to select parts of

6188-445: The measurements were limited by wool, although photographs of the experiments indicate that only limited facial wool regrowth had occurred since shearing. In addition to facial wool (in some breeds), visual field limitations can include ears and (in some breeds) horns, so the visual field can be extended by tilting the head. Sheep eyes exhibit very low hyperopia and little astigmatism . Such visual characteristics are likely to produce

6279-611: The officer-in-charge of the laboratory. In 1928, his thesis on the hydatid parasite was accepted by the University of Sydney for the degree of Doctor of Veterinary Science. Work at the McMaster Laboratory on the control of sheep liver-fluke, made a significant improvement to animal health and the returns from agriculture in the 1930s. Following his time at the McMaster Laboratory, Clunies Ross spent times in Asia , and he

6370-557: The only species of mammal except for humans which exhibit exclusive homosexual behavior . About 10% of rams refuse to mate with ewes but readily mate with other rams, and thirty percent of all rams demonstrate at least some homosexual behavior. Additionally, a small number of females that were accompanied by a male fetus in utero (i.e. as fraternal twins ) are freemartins (female animals that are behaviorally masculine and lack functioning ovaries ). Sheep may fall victim to poisons, infectious diseases , and physical injuries. As

6461-415: The plant that are easier to digest or higher in nutrition. Sheep, however, graze well in monoculture pastures where most goats fare poorly. Like all ruminants, sheep have a complex digestive system composed of four chambers, allowing them to break down cellulose from stems, leaves, and seed hulls into simpler carbohydrates . When sheep graze , vegetation is chewed into a mass called a bolus , which

6552-638: The position of other sheep in the flock. This constant monitoring is probably what keeps the sheep in a flock as they move along grazing. Sheep become stressed when isolated; this stress is reduced if they are provided with a mirror, indicating that the sight of other sheep reduces stress. Taste is the most important sense in sheep, establishing forage preferences, with sweet and sour plants being preferred and bitter plants being more commonly rejected. Touch and sight are also important in relation to specific plant characteristics, such as succulence and growth form. The ram uses his vomeronasal organ (sometimes called

6643-421: 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

6734-403: The ram during courting; somewhat similar rumbling sounds may be made by the ewe, especially when with her neonate lambs. A snort (explosive exhalation through the nostrils) may signal aggression or a warning, and is often elicited from startled sheep. In sheep breeds lacking facial wool, the visual field is wide. In 10 sheep (Cambridge, Lleyn and Welsh Mountain breeds, which lack facial wool),

6825-573: The resulting breed development, began in either southwest Asia or western Europe. 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, and the earliest woven wool garments have been dated to two to three thousand years later. Sheep husbandry spread quickly in Europe. Excavations show that in about 6000 BC, during

6916-425: The rumen, feed passes into the reticulum and the omasum ; special feeds such as grains may bypass the rumen altogether. After the first three chambers, food moves into the abomasum for final digestion before processing by the intestines . The abomasum is the only one of the four chambers analogous to the human stomach, and is sometimes called the "true stomach". Other than forage, the other staple feed for sheep

7007-469: The rump to prevent fly-strike, normally performed when the sheep is a lamb. Nose bots are fly larvae 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 and viral diseases affect sheep. Diseases of

7098-449: The same species or a group for which geographical and/or cultural separation from phenotypically similar groups has led to acceptance of its separate identity." Almost all sheep are classified as being best suited to furnishing a certain product: wool, meat, milk, hides, or a combination in a dual-purpose breed. Other features used when classifying sheep include face color (generally white or black), tail length, presence or lack of horns, and

7189-442: The sheep has 20 teeth. Mature sheep have 32 teeth. As with other ruminants, the front teeth in the lower jaw bite against a hard, toothless pad in the upper jaw. These are used to pick off vegetation, then the rear teeth grind it before it is swallowed. There are eight lower front teeth in ruminants, but there is some disagreement as to whether these are eight incisors , or six incisors and two incisor-shaped canines . This means that

7280-579: The spread of sheep raising. Pliny the Elder , in his Natural History ( Naturalis Historia ), speaks at length about sheep and wool. European colonists spread the practice to the New World from 1493 onwards. Domestic sheep are relatively small ruminants, usually with a crimped hair called wool and often with horns forming a lateral spiral . They differ from their wild relatives and ancestors in several respects, having become uniquely neotenic as

7371-573: The status quo. When Payne-Scott's marriage and pregnancy were revealed, the two had a hostile exchange of letters, and CSIRO consequently deprived her of permanent employee status and pension funds. In 1954, Clunies Ross was knighted and appointed Order of St Michael and St George (CMG), and made a Foundation Fellow of the Australian Academy of Science (FAA). He died of atherosclerotic heart disease on 20 June 1959 in Melbourne, and

7462-568: The veterinary profession, advocating for veterinarians as essential services during the COVID-19 pandemic and research into the deadly Hendra Virus . The AVA has published the Australian Veterinary Journal since 1925. Ian Clunies Ross Sir William Ian Clunies Ross CMG FAA (22 February 1899 – 20 June 1959) was an Australian veterinary scientist . He has been described as

7553-411: The visual field ranged from 298° to 325°, averaging 313.1°, with binocular overlap ranging from 44.5° to 74°, averaging 61.7°. In some breeds, unshorn facial wool can limit the visual field; in some individuals, this may be enough to cause "wool blindness". In 60 Merinos, visual fields ranged from 219.1° to 303.0°, averaging 269.9°, and the binocular field ranged from 8.9° to 77.7°, averaging 47.5°; 36% of

7644-830: The way for invasive plants. However, sheep also prefer to eat invasives such as cheatgrass , leafy spurge , kudzu and spotted knapweed over native species such as sagebrush , making grazing sheep effective for conservation grazing . Research conducted in Imperial County, California compared lamb grazing with herbicides for weed control in seedling alfalfa fields. Three trials demonstrated that grazing lambs were just as effective as herbicides in controlling winter weeds. Entomologists also compared grazing lambs to insecticides for insect control in winter alfalfa. In this trial, lambs provided insect control as effectively as insecticides. Sheep are flock animals and strongly gregarious; much sheep behavior can be understood on

7735-662: The word sheep began in Middle English as a derivation of the Old English word scēap . A group of sheep is called a flock. Many other specific terms for the various life stages of sheep exist, generally related to lambing, shearing, and age. As a key animal in the history of farming, sheep have a deeply entrenched place in human culture, and are represented in much modern language and symbolism . As livestock, sheep are most often associated with pastoral , Arcadian imagery. Sheep figure in many mythologies —such as

7826-756: Was a notable member of the Australian Veterinary Association . He was a vocal commentator on international affairs throughout the remainder of his career. In 1943, Clunies Ross was appointed Director of Scientific Personnel in the Commonwealth Directorate of Manpower and also Adviser on the Pastoral Industry to the Department of War Organization of Industry. He held these positions until 1945 while continuing work connected with his university position. At

7917-421: Was confirmed in "visual cliff" experiments; behavioral responses indicating depth perception are seen in lambs at one day old. Sheep are thought to have colour vision, and can distinguish between a variety of colours: black, red, brown, green, yellow, and white. Sight is a vital part of sheep communication, and when grazing, they maintain visual contact with each other. Each sheep lifts its head upwards to check

8008-640: Was funded to continue research at the Sydney University Veterinary School. On 6 October 1927, he married English honours graduate Janet Carter at the Catholic Apostolic Church, Redfern. They had three sons: Anthony, Adrian and David. By mid-1931, three other researchers were working with him, and in November 1931 the team moved into CSIR's new McMaster Animal Health Laboratory. Clunies Ross was appointed as

8099-943: Was given a temporary lectureship in veterinary anatomy; the following year he was made a Fellow of The Walter and Eliza Hall Institute of Medical Research , allowing him to a travel overseas. He spent a year working on animal parasites at the Molteno Institute for Research in Parasitology in Cambridge and the School of Tropical Medicine in London . He also spent time in the United States , mainly in Texas and Louisiana , where he looked at methods of field control of parasitic diseases. When he returned to Sydney he set up

8190-551: Was president of the Melbourne Wallaby Club 1954 – 1955. While in his role at the CSIRO Clunies Ross came into conflict with pioneering radio astronomer Ruby Payne-Scott over the role of women in the organization, and her role in particular. The two met in person to discuss the disparity in pay and working conditions between male and female employees of CSIRO, but this did not result in change to

8281-736: Was the Australian representative at the International Wool Secretariat in London from 1937 to 1940. He enjoyed this administrative role. He also served as a member of Australia's delegation to the League of Nations Assembly in 1938. He and his family returned to Australia when World War II broke out, he returned to the Veterinary school at the University of Sydney. He was president of the Australian Institute of International Affairs from 1941 to 1945. He

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