The Mammoth Jackstock is a breed of donkey known for its large size and strength. Originating in the United States, these donkeys were developed in the 19th century by crossing Spanish and Italian donkeys. They are primarily used for breeding mules, as their size and temperament make them ideal for this purpose. Mammoth Jackstock donkeys typically stand between 14.2 and 15.2 hands high and can weigh between 800 to 1,200 pounds. They have a calm demeanor and are known for their intelligence, making them easy to train. Their distinctive appearance includes long ears and a sturdy build, contributing to their popularity among farmers and breeders.