* Different species: Horses and zebras are different species, even though they are closely related. This means they have significant genetic differences.
* Behavioral differences: Horses and zebras have distinct mating behaviors and social structures. They may not recognize each other as potential mates.
* Physical differences: There are physical differences in the size and shape of their genitals, making successful mating difficult.
What if they were forced to breed?
While it's theoretically possible to artificially inseminate a horse with zebra sperm or vice versa, the resulting offspring would likely be:
* Infertile: The offspring would be a hybrid, and hybrids are often infertile.
* Unpredictable: The appearance and traits of the offspring would be unpredictable, as there's no way to know how the genes from each parent would combine.
* Ethical concerns: There are ethical concerns about forcing animals to breed if it's not natural for them.
The "Zorse"
There have been very rare instances of horses and zebras breeding in the wild, and even rarer instances of artificial breeding. The offspring of a horse and zebra is called a "zorse" or "zebrinny." These animals are usually infertile and often have a blend of horse and zebra characteristics, making them unique and interesting but not a common or practical outcome.