But while mules have turned out to be extremely valuable work animals, neither mules nor hinnies can mate among themselves to produce their own offspring because of their odd origins. Here's why: Humans have 23 pairs of chromosomes, which enable your genetic information to be passed on to your children.
Those mismatched chromosomes make it hard to make viable sperm and eggs. So mules are sterile because horse and donkey chromosomes are just too different.
He explained that mules have an odd number of chromosomes and therefore cannot reproduce. "To get a mule, you take a male donkey and breed it to a mare horse," he said.
A mule has 63 chromosomes, intermediate between the 64 of the horse and the 62 of the donkey. Mules are usually infertile for this reason. Pregnancy is rare, but can occasionally occur naturally, as well as through embryo transfer. A few mare mules have produced offspring when mated with a horse or donkey stallion.
It is not uncommon for female mules to come into estrus and for male mules to display signs of teasing other female equine when in estrus. Most mule owners will castrate male mules, and some will even spay female mules (remove the ovaries) in hopes of changing behavior associated with estrus or aggression.
Although there are very few studies on the heat cycle of mollies, it is known that they are sterile but still cycle normally.
For example, mules are born when a male horse mates with a female donkey. This produces a genetically distinct creature, a mule, which happens to be sterile as a species and so incapable of reproduction. By our first definition of life, therefore, we cannot classify a mule as alive.
Sex: Male is a 'horse mule' (also known as a 'john' or 'jack'). Female is a 'mare mule' (also known as a 'molly'). Young: A 'colt' (male) or 'filly' (female).
Except for the long ears, mules look very similar to horses, but their muscle composition is different. Mules have smoother muscles than horses. Think of a football player's muscle build compared to that of a ballerina's. Both are very strong, but the mule has greater physical strength for its size, and more endurance.
A male horse and a female donkey have a hinny. A female horse and a male donkey have a mule. But hinnies and mules can't have babies of their own. They are sterile because they can't make sperm or eggs.
Mules are a hybrid of a mare (female horse) and a male donkey, but a mule is more intelligent than either. This has been tested scientifically and shown. It is also an example of something called “hybrid vigor.” More on this below.
A jackass is just a male donkey.
This derives from the male donkey's nickname "jack" paired with the original donkey terminology "ass." Female donkeys are called "jennies" or "jennets," but a female ready to breed is known as a "broodmare."
Mules can live up to 50 years, with an average lifespan of 30-40 years.
All male mules (johns) and most female mules (mollies) can't reproduce. But why are mules sterile? The key is in the chromosomes.
A hinny is the offspring of a male horse and a female donkey, while a mule is the offspring of a female horse and a male donkey.
The horse has 64 chromosomes (32 pairs), and the donkey has 62 (31 pairs). When they are mated, the mule receives 63 chromosomes (32 from the horse and 31 from the donkey). During meiosis, the chromosomes are not in pairs, and, as their number is halved, the sex cells usually end up without a complete set.
Mules are one of the most commonly used working animals in the world, highly prized for their hardiness and docile nature. In countries from North Africa to Southeast Asia, mules pull carts to market, carry people across rough terrain, and help their owners to till the soil.
Breeding: A donkey bred to a donkey produces a donkey. Donkey jacks are crossed on horse mares to produce mules, while the opposite cross (stallion x donkey jennet) gives a hinny. There are few pure breeds of donkey in the United States, where they are known by their sizes and types.
Because of hybrid vigor, mules actually have more stamina and can carry more weight than a horse of the same size. Mules excel at the high-jump and can clear jumps taller than their own height from a standing start.
But while mules have turned out to be extremely valuable work animals, neither mules nor hinnies can mate among themselves to produce their own offspring because of their odd origins. Here's why: Humans have 23 pairs of chromosomes, which enable your genetic information to be passed on to your children.
Hinnies are less popular because people think they have bad attitudes, and it can be more difficult for a jenny to conceive and give birth. Donkeys also tend to have longer gestation periods than horses, and the size of the stallion is important for the health and safety of the jenny (and the foal).
Often more intelligent than their parents, mules tend to enjoy social interaction. They tend to be gentle, docile creatures, making them great family pets as well as working animals.
Mules are sterile but female mules are known to produce milk.
The gene pool containing genes of 'our mule' can of course evolve through natural selection. The conclusion is the following: mule is a living individual, because it is a part belonging to an evolving population.
In donkeys, a higher likelihood of occurrence of pregnancy was possible when the foal heat occurred 8 or more days after parturition. Similarly, a significantly higher probability of pregnancy was found when ovulation occurred 12 days or more after foaling.