A beautiful saddle mule. Mules have fully haired tails. Courtesy American Donkey and Mule Society
American Donkey and Mule Society, Inc.
P.O. Box 1210
Lewisville, Texas 75067
www.lovelongears.com
The mule is not a species in the truest sense of the word, but instead it is a hybrid resulting from the cross of two related equine species, the horse and the donkey (ass). Like both parent breeds, mules have a past that dates far back into antiquity
They once were thought of only as work or draft animals and historically were utilized for their hardworking capabilities. With their steadfastness in harness, they proved repeatedly over the centuries that they were invaluable in shaping world history. In early America, thousands of mules were bred and sold for army use, and in some areas of the country where a horse could not withstand the working conditions, mules were used exclusively. They hauled huge wagon trains of coal, borax, and supplies across the harsh, dry expanses of Death Valley, where most horses would not survive.
No records of breeding or exact numbers were kept or any registry book started for mules back then. In recent years, however, they have been viewed as recreation animals, and today there are at least three registries for mules, as well as numerous clubs for their promotion and showing all over the United States.
The Mighty Mule
The mule will take much of its overall build and looks from the mare (or horse sire in hinnies), but also acquire the unique features and hybrid vigor contributed by the donkey parent. Due to this hybrid vigor, the mule is a heartier animal than the horse. It is more suited for heavy work with less damaging effects, although this does not condone overworking it. The mule is a more efficient converter of feed to energy. When a side-by-side comparison of horse and mule is done, the mule can carry a heavier load for a longer amount of time on less feed and with greater stamina. Additionally, it has an overall longer working life, and those aged forty years or older are not unheard of.
Mules will not endanger themselves in the way that some horses will (such as when Pony Express riders often rode horses to death), but instead will stop before injuring themselves. This self-preserving nature has led to the bad reputation of mules being stubborn, but it is actually a lack of communication and interpretation on the human’s part.
This saddle mule (Standard jack x Quarter Horse mare) is more horse-like. Leah Patton
Mules can be “customized” to any type or purpose, and therefore are probably the most versatile equine of all. With more stamina, a greater weight carrying capacity, and a willing but cautious nature, the mule can perform all of the tasks and disciplines of the horse and some that it cannot. Depending on the breed of mare, the mule can be bred for endurance (Arab breeding), riding (stock or warmblood), ranch work (mustang and stock breeds), miniature (pony and Miniature Horse), packing, harness, gaited, or draft. It can range in size and type from the smallest miniature (record is 25 inches) to the largest draft (recorded at 19.1 hands). Almost every breed of horse, at one time or another, has been used for mule breeding, either en masse or as an experiment by jack owners. Just as in the past, good mules can still bring higher prices than saddle horses due to the increased demand.
This good-sized mule is the result of a draft cross (Percheron). Courtesy American Donkey & Mule Society
At large shows across the nation, the same mule can compete and win in a variety of events, from western pleasure to hunter over fences, obstacle driving to children’s lead-line, and from barrel racing to the mule’s unique sport of coon jumping. The latter is a high-jump from a standing start, where mules have been known to jump more than a foot higher than their own ears in height. Mules are even used for racing. In 2003, history was made when the first equine ever to be cloned was born—a full brother to a top winning racing mule.
Genetics
In the strictest sense of the word, the mule is the result of breeding a jack (male) donkey to a mare (female) horse. The hybrid offspring can be either a male mule, called “horse mule,” or female mare mule. The opposite pairing of a horse stallion to a donkey jennet results in a “hinny.” Mules and hinnies are virtually identical for all practical purposes and are often cataloged together under the single generic term “mule.” There is actually more variety in the physical appearance of mules and hinnies in general, than there is between the two.
Unless it is verified whether the sire was a stallion or a jack, all mule-appearing hybrids are listed as mules. There is no 100 percent reliable way, outside of DNA verification, to tell a hinny from a mule, and very few people, even experts on mules, can catalog mules and hinnies just by visual inspection. One supposedly foolproof way in sorting mules and hinnies of unverified parentage is to turn the animal into a mixed group of horses and donkeys. The mule reportedly chooses horses for company, while the hinny will go with the donkeys, both preferring to be with their mother types.
Breeding for mules is actually far more profitable and easier than breeding for hinnies. The overall fertility rate of horses is thought to be around 65 percent. This is not affected if the mare is bred to a jack; in fact, there are many old tales about previously barren mares being bred by jacks and raising healthy mule foals. When the gene tables are turned, however, and the chromosome count of the female (in this case the donkey jennet with sixty-two chromosomes) is lower than that of the male (sixty-four in the horse stallion), the conception and birth rate drops off sharply. Only about one in ten breedings in crossing for hinnies will result in a successful birth.
It is also far easier to keep one jack and a number of mares than to have a horse stallion to breed only to jennets. Jacks will usually willingly breed mares, especially if they are brought up with a mare, but a jack that is good on mares should not be put to the jennets as a rule. Horse stallions are more difficult to breed to jennets, as it is not as normal for them to be with donkeys.
Mules and hinnies both are sterile due to an imbalance of the sex chromosomes, but they are anatomically normal and behave as such. Female mules and hinnies will still come into heat, and males will show a strong sex drive. Since they often will go into a kind of rut to the exclusion of all other outside factors, male hybrids should always be castrated (preferably as soon as the testicles are descended). Uncastrated (stud) mules can be one of the most unpredictable and dangerous of all equines. Intact male mules were often let out with range mare bands at the turn of the twentieth century, as the mule would defend his mares to the death. This was done also as a way of population control, since no foals would result in the coverings.
Once in a great while, a report of a female mule or hinny giving birth surfaces. Until recent years, these were impossible to verify. With the advent of DNA testing, it can now be reported that about one in 1 million female mules may actually be fertile. It was once thought that the fertile mare mule contributed a complete set of maternal chromosomes, but at least two DNA verified hybrid offspring from fertile mare mules and hinnies have been shown to have mixed maternal gene sets (both horse and donkey). These events are highly publicized, hotly debated, and intensely studied when they do occur. No male mule has ever been known to have sired a foal, but the occurrence of female hybrid fertility has been documented in several other animal species as well.
Conformation Characteristics
Drawing on the unique features of the donkey parent, the mule is an unusual blend of horse and ass. The head is usually horse-like, but many mules have the deeper jaw, shorter face, and D-shaped eye socket of the donkey parent. Donkeys and many mules have an expression of perpetual surprise or patience due in part to the eye shape.
The mule’s ears are noticeably larger than that of a horse, but not typically so large or open as donkey ears. The neck is rarely muscled or arched, a straight neck being more common. Depending on the exact cross of parents, the neck may be thin or drafty, but ewe necks, thin, weedy swan necks, or overly short necks are not preferred in the working mule.
The barrel is wider than that of a donkey, but many mules inherit the flat withers of the jack. This makes for a level topline that blends smoothly into a rounded rump. The shoulders are often straighter (more upright), but some mules, especially those of gaited breeding, may have deep sloping shoulders. The haunches of the mule are powerful, but still not overly muscled or heavily clad as the bunchy muscle of the stock bred horse.
The mule in general will have a smooth appearance resulting from the smooth body form of the donkey, rather than the clearly defined heavy muscle of some horse breeds. Even draft mules from the largest Belgian or Percheron mares will be less bulky in shape and form and will usually have abundant bone, but are clean limbed with very little or no leg feathering.
The mane of the mule is often unruly, many being sparse and tending to stand upright like the donkey’s mane. There are numerous mane styles that can be worn on mules; preference is given to the style that best enhances the looks of the individual. It is common to see mules with very short, upright trimmed manes of only an inch or so in length, hogged (roached) flat to the neck, or trimmed in a standing curve. A few mules will have manes of both length and texture suited to laying flat on the neck; these may be thinned, braided, or banded for show. As the donkey has no falling forelock, many mules have thin or short forelocks that are usually taken off if the mane is clipped.
A more distinctive mule with white legs is the offspring of a jack with a tobiano spotted mare. Courtesy American Donkey and Mule Society
Tail styles also vary regionally and according to the preference of the owner. While a mule’s tail is fully haired from the dock to the root (unlike the cow-like switch of the donkey), mules in the past had the top portions of the tail shaved down from 4 to 10 inches. This practice helped to accentuate the haunches. Alternately, army mules had “bells” of hair clipped into the tail, in order to signify the amount of training the mule had received.
Color
Colors in the mule run nearly every gamut of horse and donkey color, every combination imaginable, and can include a few variations that are unique to the hybrids. Bay, black, brown, chestnut, buckskin, and dun are common, and most of these colors have lighter “mealy” points (or blond, pangare points) around the eyes, muzzle, and belly inherited from the donkey parent. Some have dorsal stripes and shoulder bars. Since there is no cream gene in the donkeys, mules cannot be cremello or perlino, but there are registered mules of silver dapple, champagne, and champagne/cream shades.
Random white markings such as a star, blaze, or white socks are actually uncommon in mules. The extent of random white in donkeys is usually limited to a forehead star (a blaze face, or blaze in combination with a white foot, indicates spotting in the donkey). This may be due to a masking of a sabino gene that is readily inherited by the mule.
Tobiano patterns from the horse are not transmitted in complete form to the mule or hinny offspring. Most often a mule from a tobiano mare will have only four white stockings and a white tail marking. Very few mules appear to be true tobiano in pattern, but many exhibit what is known as “skewing” of the pattern. The patches of white appear irregularly, are displaced, or are an unusual size on the mule. Skewing can occur with the tobiano pattern (true overo and sabino being almost unheard of), the donkey spot pattern (with a solid colored horse parent and spotted donkey parent), and most dramatically in the Appaloosa bred mule. Combinations of Appaloosa horse and spotted donkey can result in wildly spectacular patterns of splash and spot, or even in all-white, pink skinned, blue eyed mules.
Breeding for color on mules is a true spin of the roulette wheel, and color is always figured into the equation as the icing on the cake, with temperament and conformation being the first goals in breeding.
Standards
The American Donkey and Mule Society, founded in 1967, operates five books for donkeys, mules, and zebra hybrids, including the registry for racing mules, which are popular in Nevada and California.
The mule should follow, in part, the breed of the horse parent with regard to head carriage, gait, and body shape. The main ideal for a mule is to be well balanced, straight, and clean legged, with no major conformation flaws outside the “equine normal” (severely ewed neck, cowhocks, or crooked legs for example).
Heads should be in proportion to the body and not overly large. Unlike other horse breeds with infusions of Arab blood, Arabian mules may have straight faces. Heavy Roman noses or coarse heads do not hamper a working mule, but are not preferred for showing.
Bite should be even, with less than one-fourth inch deviation preferred. Neck should be straight and set well into shoulder. Extreme ewe or swan necks are penalized, and very short, thick or Long, thin necks are not preferred in show stock, but do not affect most working mules.
Forelegs should be set on well with clear projection of chest in front. Shoulders are often straight, but a gentle slope is preferred. Legs should be square and straight when viewed from front and side.
Chests should be broad with defined, double-lobed breast musculature.
Barrels should be deep with plenty of heart girth and should not be long and weak.
Flatter withers than horses are not uncommon, but good withers and saddle dip are preferred in riding animals.
Underlines should be long and straight, tying into flank at a deeper set than horses.
Hips should be long and smooth; haunches large and well muscled; hindquarters should be in balance to shoulders. Very shallow hindquarters and weak hind ends are to be penalized.
The hind limbs of saddle or draft mules are shown standing square, while gaited mules may be stretched. The hind legs should be set under well without being sickle hocked. When viewed from behind, the hind legs should be straight with a small degree of cowhocks allowed. Severe cowhocks or crooked legs are to be penalized.
Pasterns are slightly more upright than what is normal in horses, but pastern and hoof angles should match. Club feet and long, broken hoof angles are severely penalized.
Mules perform all known gaits; those from Walking Horse mares may rack, amble, or single-foot. Exaggerated high-stepping action can be enhanced in the naturally gaited mule.
The hocks are the power “train” and should be well engaged. Headset should be that of the breed/usage of the mule.
Credit: American Donkey and Mule Society, Inc.