Mammoth Jackstock (American Mammoth)

Donkey

The American Mammoth Donkey, commonly known as the Mammoth Jack, or American Mammoth Jack is a descendant of multiple breeds of donkey imported to the United States. Breeds that influenced the Mammoth Jack include the Maltese donkey, Poitou donkey (also sometimes called a Mammoth Donkey), Andalusian donkey, Majorcan donkey, and Catalonian donkeys. Males, called Jacks, must be at least 14 hands (56 inches, 142 cm) and females, called jennies or jennets must be at least 13.2 hands (54 inches, 137 cm).

http://en.wikipedia.org/wiki/American_Mammoth_Jack