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The Morgan horse is one of the earliest horse breeds developed in the United States.〔(【引用サイトリンク】title=Frequently Asked Questions )〕 Tracing back to the foundation sire Figure, later named Justin Morgan after his best-known owner, Morgans served many roles in 19th-century American history, being used as coach horses and for harness racing, as general riding animals, and as cavalry horses during the American Civil War on both sides of the conflict. Morgans have influenced other major American breeds, including the American Quarter Horse, Tennessee Walking Horse and the Standardbred. During the 19th and 20th centuries, they were exported to other countries, including England, where they influenced the breeding of the Hackney horse. In 1907, the US Department of Agriculture established the US Morgan Horse Farm in Middlebury, Vermont for the purpose of perpetuating and improving the Morgan breed; the farm was later transferred to the University of Vermont. The first breed registry was established in 1909, and since then many organizations in the US, Europe and Oceania have developed. There were estimated to be over 175,000 Morgan horses worldwide in 2005. The Morgan is a compact, refined breed, generally bay, black or chestnut in color, although they come in many colors, including several variations of pinto. Used in both English and Western disciplines, the breed is known for its versatility. The Morgan is the state animal of Vermont and the state horse of Massachusetts. Popular children's authors, including Marguerite Henry and Ellen Feld, have portrayed the breed in their books; Henry's ''Justin Morgan Had a Horse'' was later made into a Disney movie. ==Breed characteristics== There is officially one breed standard for Morgan type, regardless of the discipline or bloodline of the individual horse. Compact and refined in build, the Morgan has strong legs, an expressive head with a straight or slightly convex profile and broad forehead; large, prominent eyes; well-defined withers, laid back shoulders, and an upright, well arched neck.〔 The back is short,〔 and hindquarters are strongly muscled,〔 with a long and well-muscled croup. The tail is attached high and carried gracefully and straight.〔 Morgans appear to be a strong powerful horse,〔 and the breed is well known as an easy keeper.〔 The breed standard for height ranges from , with some individuals over and under.〔 Gaits, particularly the trot are "animated, elastic, square, and collected," with the front and rear legs balanced. A few Morgans are gaited, meaning they can perform an intermediate speed gait other than the trot such as the rack, fox trot, or pace.〔 The United States Equestrian Federation states, "a Morgan is distinctive for its stamina and vigor, personality and eagerness and strong natural way of moving." The breed has a reputation for intelligence, courage and a good disposition.〔 Registered Morgans come in a variety of colors although they are most commonly bay, black, and chestnut. Less common colors include gray, roan, dun, silver dapple, and cream dilutions such as palomino, buckskin, cremello and perlino.〔 In addition, three pinto color patterns are also recognized: sabino, frame overo, and splashed white. The tobiano pattern has not been noted in Morgans. One genetic disease has been identified within the Morgan breed. This is Type 1 polysaccharide storage myopathy, an autosomal dominant muscle disease found mainly in stock horse and draft horse breeds caused by a missense mutation in the GYS1 gene. Morgans are one of over a dozen breeds found to have the allele for the condition, though its prevalence in Morgans appears to be quite low compared to stock and draft breeds. In one study, less than one percent of randomly tested Morgans carried the allele for this condition, one of the lowest percentages amongst breeds in that study. Two coat color genes found in Morgans have also been linked to genetic disorders. One is the genetic ocular syndrome multiple congenital ocular anomalies (MCOA), originally called equine anterior segment dysgenesis (ASD). MCOA is characterized by the abnormal development of some ocular tissues, which causes compromised vision, although generally of a mild form; the disease is non-progressive. Genetic studies have shown that it is closely tied to the silver dapple gene. A small number of Morgans carry the silver dapple allele, which causes cysts but no apparent vision problems if heterozygous, but when homozygous can cause vision problems. There is also the possibility of lethal white syndrome, a fatal disease seen in foals who are homozygous for the frame overo gene. At present, there is one mare line in the Morgan breed that has produced healthy heterozygous frame overo individuals. The American Morgan Horse Association advocates genetic testing to identify carriers of these genetics, and advises owners to avoid breeding horses that are heterozygous for frame overo to each other. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Morgan horse」の詳細全文を読む スポンサード リンク
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