Due to the chromosomal mismatch, nearly all mules and hinnies are sterile. Their reproductive organs develop normally, and they exhibit standard hormonal drives (intact male mules will still behave like stallions), but they cannot produce viable gametes.
From the Roman Empire to the American westward expansion, hybrid equines have been the unsung engines of human progress. They pulled heavy artillery through muddy trenches in World War I, hauled silver out of South American mines, and packed gear across the Grand Canyon. Even today, in rugged terrains where motorized vehicles cannot go, the product of the horse and donkey remains irreplaceable. Horse Mating Donkey
: Their offspring ( mules and hinnies ) have 63 chromosomes. This uneven number generally prevents the hybrids from producing their own germ cells, making almost all mules and hinnies sterile. Mating Behaviors Due to the chromosomal mismatch, nearly all mules