hinny

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The word "hinny" is also a term of endearment used in North East England, equivalent to "honey"; see Geordie.

Hinny
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Perissodactyla Family: Equidae Genus: Equus Species: E. caballus + E. asinus
Binomial name
none
Synonyms
Equus mulus

A hinny is a domestic equine hybrid which is the offspring of a male horse and a female donkey (called a jenny or, less often a jennet). It is similar to the more common mule, but mules are the product of a female horse and a male donkey.

Physical description

Hinnies are on average slightly smaller than mules. There is much speculation as to the size variances among the two types of hybrids. Some fanciers feel this size difference is merely physiological, due to the smaller size of the donkey dam, as compared with a much larger mare. Others claim it is genetic, but the view of the American Donkey and Mule Society is, "The genetic inheritance of the hinny is exactly the same as the mule."

Thus hinnies are smaller because donkeys are, for the most part, smaller than horses, and the growth potential of equine offspring is influenced by the size of the dam's womb. Hinnies do however, like mules, come in many sizes. This is because donkeys come in many sizes, from miniatures as small as 24 inches (610 mm) at the withers, to Mammoth donkey jacks and jennies that may be over 15 hands, approximately 60 inches (1524 mm) at the withers. Thus, a hinny is restricted to being about the size of the largest breed of donkey. Mules, however, have a female horse as a parent, so they can be as large as the size of the largest breed of horse. There are some huge mules, mostly from work horse breeds such as the Belgian.

Other than size, there are some minor differences that occur frequently between mules and hinnies. The head of a hinny resembles that of a horse, more so than mule heads do. Hinnies often have shorter ears, although they are still longer than those of horses, and more horse-like manes and tails than mules do. Hinnies coats are usually one of the horse colors, as the male parent most often determines the color of the coat. (Mules on the other hand usually have donkey coat colors.) Certain traits, like the popular gait that some horses and donkeys possess, seem to pass more readily through the male parent. Therefore, many people have tried to produce gaited hybrids by using gaited male horses with female donkeys, in hopes of creating gaited hinnies.

Fertility, sterility, and rarity

Hinnies are difficult to obtain because of the differences in the number of chromosomes of the horse and the donkey. A donkey has 62 chromosomes, whereas a horse has 64. Hinnies, being hybrids of those two species, have 63 chromosomes and are sterile. The uneven number of chromosomes results in an incomplete reproductive system. According to the ADMS, "The equine hybrid is easier to obtain when the lower chromosome count, the donkey, is in the male. Therefore breeding for hinnies is more hit-and-miss than breeding for mules."[1]

Male hinnies and mules are usually castrated to help control their behavior by eliminating their interest in females. The male hinny or mule can and will mate, but the emission is not fertile. There are no recorded cases of fertile male hinnies or male mules.

Female hinnies and mules are not customarily spayed, and may or may not go through estrus. Female mules have been known to produce offspring when mated to a purebred horse or donkey, though this is extremely uncommon. Since 1527 there have been more than sixty documented cases of foals born to female mules around the world. In contrast, according to the ADMS, there is only one known case of a female hinny doing so, and she produced a mix which has, thus far, only been documented once among the offspring of female mules:

• Mule mares pass along 100% of their maternal genes to their offspring, rather than a mix. Since a mule's mother is a horse, as a rule mule mares pass genes which are 100% horse to their foals. Thus, a mule mare bred to a horse stallion will produce a foal which is 100% horse, with no donkey genes at all.

• In China in 1981, a hinny mare proved fertile with a donkey stallion. Scientists expected a 100% donkey foal if the female hinny had passed on her maternal chromosomes the same way as female mules do. However, when the Chinese hinny was bred to a donkey jack, she produced "Dragon Foal," who resembled a donkey with mule-like features. Dragon Foal's chromosomes and DNA tests confirmed that she was a previously undocumented combination - That is, she was not the expected gene combination of 'donkey-donkey' (from her donkey father) / 'donkey-donkey' (If her hinny mother were to have passed on her maternal donkey genes). Instead, Dragon Foal's gene pair combination was donkey-donkey/donkey-horse. Her hinny mother passed along a combination of maternal and paternal genes.

• In Morocco in 2003, a mule mare bred to a donkey stallion produced a male foal that was 75% donkey and 25% horse. DNA testing revealed the Moroccan foal is a mixed karyotype hybrid like the Chinese hinny offspring, Dragon Foal. This means that, unlike regular hinnies, whose 63 chromosomes consist of 31 pairs that are horse-donkey with one left over, the Morocco colt has about 23 pairs of chromosomes that are donkey-donkey, eight pairs that are horse-donkey, and one left over.

• Because of the mix of gene pairs in the Moroccan foal, it's unknown whether Dragon Foal's genetic oddity is due to her mother being a hinny rather than a mule, or if there is some other factor that applies equally to Dragon Foal in China and the 2003 colt in Morocco.

There are other reasons for the rarity of hinnies. Female donkeys, jennies, and male horses, stallions, are choosier about their mates than horse mares and donkey jacks. Thus, the two parties involved may not care to mate. Even if they do cooperate, female donkeys are less likely to conceive when bred to a horse than horse mares are when bred to a donkey. Breeding large hinnies is an even bigger challenge, as it requires a jenny of Mammoth donkey stock. Mammoth donkey stock is becoming increasingly rare and has been declared an endangered domestic breed. Fanciers are unlikely to devote a Mammoth jenny's valuable breeding time to producing sterile hinny hybrids when Mammoth females are in high demand to produce fertile pure-bred Mammoth foals.

See also

• Baudet de Poitou aka Mammoth donkey

References

• "Hinny". sciencedaily.com. Science Daily. http://www.sciencedaily.com/articles/h/hinny.htm. 
• McKinnon, Angus O.; James L. Voss (1993). Equine Reproduction. Blackwell Publishing. ISBN 9780812114270. http://books.google.com/books?id=jlZAT-9VwUIC&pg=PA537&dq=hinny&client=firefox-a&sig=ACfU3U3OzqPP0bqNnF2vejcDhtbWtldblA. 

External links

• The American Donkey and Mule Society
• Why Not Hinnies?

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