Mule

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For other uses, see Mule (disambiguation).
Mule
Juancito.jpg
Conservation status
Domesticated
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Perissodactyla
Family: Equidae
Genus: Equus
Species: Equus asinus x Equus caballus
Binomial name
None
Most mules are sterile. Sterile hybrids are not species in their own right.

Synonyms
Equus mulus

A mule is the offspring of a male donkey (jack) and a female horse (mare).[1] Horses and donkeys are different species, with different numbers of chromosomes. Of the two F1 hybrids between these two species, a mule is easier to obtain than a hinny, which is the product of a female donkey (jenny) and a male horse (stallion).

The size of a mule and work to which it is put depends largely on the breeding of the mule's dam. Mules can be lightweight, medium weight, or even, when produced from draft horse mares, of moderately heavy weight.[2]:85-87

It has been claimed that mules are "more patient, sure-footed, hardy and long-lived than horses, and they are considered less obstinate, faster, and more intelligent than donkeys."[3]:5

A female mule that has estrus cycles and thus, in theory, could carry a fetus, is called a "molly" or "Molly mule," though the term is sometimes used to refer to female mules in general. Pregnancy is rare, but can occasionally occur naturally as well as through embryo transfer. One of several terms for a gelded mule is a "John mule."

Biology[edit]

The median weight range for a mule is between about 370 and 460 kg (820 and 1,000 lb).[4] Although it depends on the individual animal, an army mule can "carry up to 72 kg and walk 26 km without resting."[5] In general, a mule can be packed with "dead weight" of up to 20% of its body weight, or approximately 90 kg (198 lb).[6] The average equine in general can carry up to approximately 30% of its body weight in "live" weight, such as a rider.[7] However, while a few mules can carry live weight up to 160 kg (353 lb), the superiority of the mule becomes apparent in their additional endurance.[6]

One of the virtues of the mule is the size and ground-covering ability of a horse, but is comparatively stronger than a horse of similar size and inherits the endurance and disposition of the donkey father. Mules also tend to be more independent than most other domesticated equines other than the donkey. Mules also tend to require less food than a horse of similar size.

There are both male and female mules. A male mule is properly called a horse mule, though often called a john mule. A female mule is properly called a mare mule, though often called a Molly mule. A young male mule is called a mule colt, and a young female is called a mule filly.[8]

Characteristics[edit]

A grey mule
Ancient Greek rhyton in the shape of a mule's head, made by Brygos, early 5th century BC. Jérôme Carcopino Museum, Department of Archaeology, Aleria

With its short thick head, long ears, thin limbs, small narrow hooves, and short mane, the mule shares characteristics of a donkey. In height and body, shape of neck and rump, uniformity of coat, and teeth, it appears horse-like. The mule comes in all sizes, shapes and conformations. There are mules that resemble huge draft horses, sturdy quarter horses, fine-boned racing horses, shaggy ponies and more.

The mule is considered a renowned example of hybrid vigor.[9] Charles Darwin wrote: The mule always appears to me a most surprising animal. That a hybrid should possess more reason, memory, obstinacy, social affection, powers of muscular endurance, and length of life, than either of its parents, seems to indicate that art has here outdone nature.[10]

The mule inherits from its sire the traits of intelligence, sure-footedness, toughness, endurance, disposition, and natural cautiousness. From its dam it inherits speed, conformation, and agility.[11]:5-6,8 Mules exhibit a higher cognitive intelligence than their parent species. This is also believed to be the result of hybrid vigor, similar to how mules acquire greater height and endurance than either parent.[12]

Handlers of working animals generally find mules preferable to horses: mules show more patience under the pressure of heavy weights, and their skin is harder and less sensitive than that of horses, rendering them more capable of resisting sun and rain. Their hooves are harder than horses', and they show a natural resistance to disease and insects. Many North American farmers with clay soil found mules superior as plow animals.

A mule does not sound exactly like a donkey or a horse. Instead, a mule makes a sound that is similar to a donkey's but also has the whinnying characteristics of a horse (often starts with a whinny, ends in a hee-haw). Sometimes, mules whimper.

Mules are generally less tolerant towards dogs (much like donkeys) than horses are.[citation needed] They are also capable of striking out with any of their hooves in any direction, even sideways if needed.[citation needed]

Color and size variety[edit]

Mules come in a variety of shapes, sizes and colors, from minis under 50 lb (23 kg) to maxis over 1,000 lb (454 kg), and in many different colors. The coats of mules come in the same varieties as those of horses. Common colors are sorrel, bay, black, and grey. Less common are white, roans (both blue and red), palomino, dun, and buckskin. Least common are paint mules or tobianos. Mules from Appaloosa mares produce wildly colored mules, much like their Appaloosa horse relatives, but with even wilder skewed colors. The Appaloosa color is produced by a complex of genes known as the Leopard complex (Lp). Mares homozygous for the Lp gene bred to any color donkey will produce an Appaloosa colored mule.

Distribution[edit]

The Food and Agriculture Organization of the United Nations (FAO) reports that China was the top market for mules in 2003, closely followed by Mexico and many Central and South American nations.

Fertility[edit]

Mules and hinnies have 63 chromosomes, a mixture of the horse's 64 and the donkey's 62. The different structure and number usually prevents the chromosomes from pairing up properly and creating successful embryos, rendering most mules infertile.

There are no recorded cases of fertile mule stallions. A few mare mules have produced offspring when mated with a purebred horse or donkey.[13] Herodotus gives an account of such an event as an ill omen of Xerxes' conquest of Greece in 480 BC: "There happened also a portent of another kind while he was still at Sardis,—a mule brought forth young and gave birth to a mule" (Herodotus The Histories 7:57).

As of October 2002, there had been only 60 documented cases of mules birthing foals since 1527.[13] In China in 2001, a mare mule produced a filly.[14] In Morocco in early 2002 and Colorado in 2007, mare mules produced colts.[13][15][16] Blood and hair samples from the Colorado birth verified that the mother was indeed a mule and the foal was indeed her offspring.[16]

A 1939 article in the Journal of Heredity describes two offspring of a fertile mare mule named "Old Bec", which was owned at the time by the A&M College of Texas (now Texas A&M University) in the late 1920s. One of the foals was a female, sired by a jack. Unlike its mother, it was sterile. The other, sired by a five-gaited saddlebred stallion, exhibited no characteristics of any donkey. That horse, a stallion, was bred to several mares, which gave birth to live foals that showed no characteristics of the donkey.[17]

Modern mules[edit]

An "Appaloosa" mule
Mules carrying slate roof tiles. Dharamsala, India. 1993
A pair of mules working a plowing exhibition at The Farnsley-Moreman House in Louisville, Kentucky
Mule moving goods in the car-free Medina in Fes, Morocco

In the second half of the 20th century, widespread usage of mules declined in industrialized countries. The use of mules for farming and transportation of agricultural products largely gave way to modern tractors and trucks. However, in the United States, a dedicated number of mule breeders continued the tradition as a hobby and continued breeding the great lines of American Mammoth Jacks started in the United States by George Washington with the gift from the King of Spain of two Catalan donkeys. These hobby breeders began to utilize better mares for mule production until today's modern saddle mule emerged. Exhibition shows where mules pulled heavy loads have now been joined with mules competing in Western and English pleasure riding, as well as dressage and show jumping competition. There is now a cable TV show dedicated to the training of donkeys and mules. Mules, once snubbed at traditional horse shows, have been accepted for competition at the most exclusive horse shows in the world in all disciplines.

Mules are still used extensively to transport cargo in rugged roadless regions, such as the large wilderness areas of California's Sierra Nevada mountains. Commercial pack mules are used recreationally, such as to supply mountaineering base camps, and also to supply trail building and maintenance crews, and backcountry footbridge building crews.[18] As of July 2014, there are at least sixteen commercial mule pack stations in business in the Sierra Nevada.[19] The Angeles chapter of the Sierra Club has a Mule Pack Section that organizes hiking trips with supplies carried by mules.[20]

Amish farmers, who reject tractors and most other modern technology for religious reasons, commonly use teams of six or eight mules to pull plows, disks, and other farm equipment, though they use horses for pulling buggies on the road.

During the Soviet war in Afghanistan, the United States used large numbers of mules to carry weapons and supplies over Afghanistan's rugged terrain to the mujahideen.[21] Use of mules by U.S. forces has continued during the War in Afghanistan (2001-present), and the United States Marine Corps has conducted an 11-day Animal Packers Course since the 1960s at its Mountain Warfare Training Center located in the Sierra Nevada near Bridgeport, California.

Mule clone[edit]

In 2003, researchers at University of Idaho and Utah State University produced the first mule clone as part of Project Idaho.[22] The research team included Gordon Woods, professor of animal and veterinary science at the University of Idaho; Kenneth L. White, Utah State University professor of animal science; and Dirk Vanderwall, University of Idaho assistant professor of animal and veterinary science. The baby mule, Idaho Gem, was born May 4. It was the first clone of a hybrid animal. Veterinary examinations of the foal and its surrogate mother showed them to be in good health soon after birth. The foal's DNA comes from a fetal cell culture first established in 1998 at the University of Idaho.

See also[edit]

References[edit]

  1. ^ "Mule Day: A Local Legacy". americaslibrary.gov. Library of Congress. 2013-12-18. Retrieved 2014-07-16. 
  2. ^ Ensminger, M. E. (1990). Horses and Horsemanship: Animal Agriculture Series (Sixth ed.). Danville, IL: Interstate. ISBN 0-8134-2883-1. 
  3. ^ Jackson, Louise A (2004). The Mule Men: A History of Stock Packing in the Sierra Nevada. Missoula, MT: Mountain Press. ISBN 0-87842-499-7. 
  4. ^ "Mule". The Encyclopaedia Britannica: A Dictionary of Arts, Sciences, and General XVII. Henry G. Allen and Company. 1888. p. 15. 
  5. ^ Khan, Aamer Ahmed (2005-10-19). "Beasts ease burden of quake victims". BBC. Retrieved 2010-04-06. 
  6. ^ a b "Hunter's Specialties: More With Wayne Carlton On Elk Hunting". hunterspec.com. Hunter's Specialties. 2009. Archived from the original on 2010-10-08. Retrieved 2014-07-16. 
  7. ^ American Endurance Ride Conference (November 2003). "Chapter 3, Section IV: Size". Endurance Rider's Handbook. AERC. Retrieved 2008-08-07. 
  8. ^ "Longear Lingo". lovelongears.com. American Donkey and Mule Society. 2013-05-22. Retrieved 2014-07-16. 
  9. ^ Chen, Z. Jeffrey; Birchler, James A., eds. (2013). Polyploid and Hybrid Genomics. John Wiley & Sons. ISBN 978-0-470-96037-0. Retrieved 2014-07-16. 
  10. ^ Darwin, Charles (1879). What Mr. Darwin Saw in His Voyage Round the World in the Ship 'Beagle'. New York: Harper & Bros. p. 33-34. Retrieved 2014-07-16. 
  11. ^ Hauer, John, ed. (2014). The Natural Superiority of Mules. Skyhorse. ISBN 978-1-62636-166-9. Retrieved 2014-07-16. 
  12. ^ Proops, Leanne; Faith Burden; Britta Osthaus (2008-07-18). "Mule cognition: a case of hybrid vigor?". Animal Cognition 12 (1): 75–84. doi:10.1007/s10071-008-0172-1. PMID 18636282. Retrieved 2008-08-10. 
  13. ^ a b c Kay, Katty (2002-10-02). "Morocco's miracle mule". BBC News. Retrieved 2009-02-05. 
  14. ^ Rong, Ruizhang; Cai, Huedi; Yang, Xiuqin; Wei, Jun (October 1985). "Fertile mule in China and her unusual foal". Journal of the Royal Society of Medicine (National Center for Biotechnology Information) 78 (10): 821–25. Retrieved 13 July 2014. 
  15. ^ "Befuddling Birth: The Case of the Mule's Foal". National Public Radio. 2007-07-26. Retrieved 2009-02-05. 
  16. ^ a b Lofholm, Nancy (2007-09-19). "Mule's foal fools genetics with 'impossible' birth". Seattle Post Intelligencer. Retrieved 2008-09-02-05. 
  17. ^ Anderson, W. S. (1939). "Fertile Mare Mules". Journal of Heredity 30 (12): 549–551. Retrieved 2014-07-16. 
  18. ^ Jackson, Louise A (2004). The Mule Men: A History of Stock Packing in the Sierra Nevada. Missoula, MT: Mountain Press. ISBN 0-87842-499-7.
  19. ^ "Members of the Eastern Sierra Packers". easternsierrapackers.com. Eastern Sierra Packers. 2009-01-18. Retrieved 2014-07-16. 
  20. ^ "Mule Pack Section, Angeles Chapter, Sierra Club". angeles.sierraclub.org. Angeles Chapter Sierra Club. 2014-04-18. Retrieved 2014-07-16. 
  21. ^ Bearden, Milt (2003) The Main Enemy, The Inside story of the CIA's Final showdown with the KGB. Presidio Press. ISBN 0345472500
  22. ^ "Project Idaho". University of Idaho. 2003-05-29. Archived from the original on 2009-08-09. Retrieved 2014-07-16. 

Further reading[edit]

External links[edit]