Here's why:
* Chromosomes: Horses have 64 chromosomes, while donkeys have 62. This difference makes it impossible for them to produce fertile offspring.
* Hybrids: When a male donkey (jack) and a female horse (mare) mate, they produce a mule. When a male horse (stallion) and a female donkey (jenny) mate, they produce a hinny.
* Infertility: Mules and hinnies are sterile, meaning they cannot reproduce. This is because the uneven number of chromosomes prevents proper cell division during the formation of gametes (sperm and egg).
While mules and hinnies are not fertile, they are often valued for their strength, hardiness, and longevity. They are commonly used for work, transportation, and recreation.