A female donkey is called a jenny, or sometimes a jennet. A male donkey is called a jack or an ass, while a young donkey is a foal. Donkeys are a family member of horses. Donkeys have been used as pack animals for over 5000 years. Male donkeys used to mate with female horses produce mules, and the offspring of a stallion and a female donkey is called a hinny. Hinnies are quite rare for many reasons. Start with the differences in the number of chromosomes in a horse in a donkey – a horse has 64, and a donkey has 62. Hinnies often are born sterile, and donkey jennies are often choosy about their mates.