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American Mammoth Jack

Country of Origin: USA

American Mammoth Jack


The world’s largest breed of ass, the American Mammoth Jack stock was developed in the US through the selective cross breeding of imported European stock with local Native American & Mexican animals.

American Mammoth Jennet


Small time breeding of these animals was common for more than 100 years prior to the development of their official registry in 1888. This is an animal developed based on the needs of people in various areas, but mainly for agricultural & transportation. The intention was to create a larger & stronger animal more capable of heavy workloads.

Attempt at Standardization

Selective breeding helped to preserve important traits, but was often limited to stock that was available for use. However, initially the registry attempted to standardize the breed by only including black animals a minimum of 15 hands tall. Over the years, these rigid type lines have blurred & the breed encompasses a number of colors/ sizes.


Jacks must be a minimum of 14.2 hands
Jennets must be a minimum of 14 hands
Incredibly strong


Head is well shaped & tapered to a round muzzle
Large, wide-set eyes & long, upright ears
Neck should be muscular but not too thick & well proportioned
Good width, depth & length of body
Strong loins & a full hip
Legs should be strong & thick
Feet are large & well cupped

Traditional Colors

Initially they were to be black with a mealy / pangare gene however cross breeding has created more colors including sorrel.


Willing & tireless
Mild mannered & kind

American Mammoth Jack


Create draft mules
Recreational use
Agricultural work
Pleasure mount

Helpful Links

*All links open in a new window
American Mammoth Jackstock Registry
American Livestock Breeds Conservancy

Where to Buy

Diamondback Mules

American Mammoth Jack Studs

Diamondback Mules
Barred M Ranch


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Country of Origin: USA | Colors: , ,
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