How Many Chromosomes Does A Horse Have?

Some friends and I got into a debate about interbreeding equine species like horses and donkeys.

We were talking about whether things like mules or hinnies could breed, since they were the result of interbreeding.

None of us were quite sure, although we all had an opinion.

I knew that it was all to do with chromosomes, though I wasn’t sure how many chromosomes horses had or exactly what that meant anyway, so I decided to look into it.

So, how many chromosomes does a horse have?

A horse has 64 chromosomes. This determines which animals it can successfully mate with and provides the genetic makeup for the offspring. Similar equine animals have similar amounts of chromosomes, but even very minor discrepancies can cause problems for breeding, especially the offspring.

Humans have a total of only 46 chromosomes, so that puts a horse’s chromosomes into some kind of context.

This topic can be really tricky to get to grips with, though, even if we all learned it in high school!

But if you didn’t listen properly back then, well here’s your second chance.

Let’s first take a look at what chromosomes are.

What are chromosomes?

Chromosomes are in the bodies of all animal and plants, and are thread-like structures located inside the nucleus of animal and plant cells.

Individual chromosomes are made of protein and a single molecule of DNA, which is what contains genetic material for having offspring.

Indeed, any cell or part of our body that needs to be developed or repaired will use the instructions in DNA.

So, from the point of view of breeding, chromosomes are essentially how living cells are passed down.

Living beings need to have self-replicating cells; this is the essential building block of life.

So, having coded instructions on how to build all the differentiated cells in the body is one of the most important parts of being alive, and that’s what chromosomes do between generations.

So, how many chromosomes do horses have?

How many chromosomes does a male horse have?

In sexually reproducing animals, half of the offspring’s genetic makeup comes from the mother and other half from the father.

Different chromosomes are essentially mixed in the offspring, then, to give the resulting genes are traits of the offspring.

Male horses have 64 chromosomes, composed of 31 autosomes which are metacentric of submetacentric.

This may sound like extremely complex science, but it’s just to do with the amount of genetic material that horse offspring get from each parent.

Both horses have the same number of overall chromosomes, but different individual chromosomes with different genetic information.

How many chromosomes does a female horse have?

Like the males, female horses also have 64 chromosomes.

The main difference is that the female horse has two X chromosomes, whereas the males have one X and one Y chromosome.

In the simplest sense, this determines the animal’s sex.

Your arrangement of X and Y chromosomes is what determines whether an organism is male or female.

In horses, two X chromosomes make a female and one of each makes a male.

Overall, though female and male horses have the same number of chromosomes.

Otherwise, they wouldn’t be able to mate properly!

How many chromosomes do donkeys have?

Undoubtedly the most common interspecies mix in the Equus family is between horses and donkeys.

Usually, a male donkey is mated with a female horse to produce a mule, which have numerous advantages over horses and donkeys when it comes to work.

You can also have hinnies, where a female donkey is mated with a stallion, but these are less common.

Donkeys have 62 chromosomes, compared to a horse’s 64.

This means that they are closely enough related that they can mate without much trouble.

However, mules and hinnies are, almost without exception, sterile.

The mixture of different species chromosomes means that they aren’t able to pass that genetic material on, and are therefore infertile.

So, while you can very easily mate animals that are closely related if they have roughly the same number of chromosomes, mating the resulting offspring is virtually impossible.

There are reported cases of such things, but they are very rare and often unsubstantiated.

Furthermore, any offspring produced by a mule or hinny would definitely not be able to mate.

How many chromosomes do zebras have?

What about zebras?

I know I have certainly wondered whether horses and zebras can produce offspring.

The answer is yes, they certainly can!

It is, however, much, much more difficult than mating horses and donkeys.

Zebras only have 44 chromosomes, which is much less than either a horse or a donkey.

This helps to put into perspective just how much easier it is to mate horses and donkeys.

The result of a horse and a zebra breeding is called a zorse, and there are many confirmed cases of such an animal.

As you can imagine, however, it’s very difficult with such a disparity in the number of chromosomes, and in many cases is not possible.

They are still closely enough related that it can happen, though.

Inter-species breeding is all about chromosomes, then, and if there’s too much of a difference in the number of chromosomes between two species, they won’t be able to mate.

If there’s only a small difference, they will be able to breed, but the overwhelming likelihood is that the offspring they produce will not be able to breed.

A horses 64 chromosomes will go well with a donkey’s 62, and produce a mule or a hinny.