American Mammoth Jackstock

By 1800 the breed had spread into Kentucky, Tennessee and the Missouri territory, which became the mule-producing heart of the country. Several thousand more large donkeys came over from Europe between 1830 and 1890, mostly Catalonian, with Andalusian, Maltese, Poitou, Majorcan and Italian blood added.

A registry formed in 1888 and a second in 1908. The two merged in 1923 as the Standard Jack and Jennet Registry, which continues today as the American Mammoth Jackstock Registry, kept by the American Mammoth Jackstock Association. The peak came around 1920, when the national herd was estimated at five million animals.

Then tractors took the work. During the 1950s the registry lowered its height requirements, to 14 hands for males and 13.2 for females, and restored the original standards in the 1980s. That dip and recovery is the low point of the breed written into its own rulebook.

This is a donkey on a draft-horse scale. The registry requires a jack to stand at least 14.2 hands, 58 inches, a jennet or gelding at least 14 hands, and every registered animal to tape at least 61 inches around the heart girth. The Livestock Conservancy puts adult weight at 900 to 1,200 lb. The frame is sturdy and tall, with massive legs and a large, well-made head, and the ears run to 33 inches from head to tip.

Black was once the only acceptable color, and sorrel is now common alongside it. The registry prefers solid colors and roans; white and spotted animals are not eligible for the herd book. The tallest living mammoth donkey stands 17 hands.

Docile is The Livestock Conservancy's word, and they bond hard to their owner.

One warning worth taking seriously: an intact jack is not a first donkey. The Conservancy is explicit that jacks should not go to owners without experience of intact equines, or to anyone who does not intend to breed. If you want a companion animal, buy a gelding.

Everything else about handling is scale. This is an equine the size of a horse, and gates, chutes and trailers need to be sized for one.

Siring mules is the founding job: a mammoth jack on a draft mare produces the heavy work mule American agriculture ran on for a century.

The Conservancy lists the modern uses as mule production using jacks, driving, riding and livestock guarding. There is no commercial mule economy left, so today the animal is a breeding animal, a saddle and harness animal, or a very large guardian.

Feed at draft scale. A very large equine eats accordingly, and like any donkey it does best on modest forage: rich pasture is a founder risk, so grazing wants managing rather than maximising.

Fencing, shelter and handling equipment sized for an animal over 14 hands. Budget for it before you bid rather than after.

From an estimated five million animals in 1920 to Critical on The Livestock Conservancy's Conservation Priority List: the tractor did that. When the draft mule stopped being the engine of American farming, the animal bred to sire it lost its market almost entirely.

The herd book is what remains of the breed's structure. The registry's stud books reach back to 1888, and registration is what separates the breed from the general population of big donkeys.

Ask for papers. The registry measures animals rather than taking a seller's word: the minimums are 14.2 hands and an 8 inch cannon bone for a jack, 14 hands and 7.5 inches for a jennet or gelding, and 61 inches of heart girth for all, and a burro cross is not eligible. A big donkey that does not meet the standard does not register. Without papers you are buying a large donkey, not a Mammoth Jackstock.

Match the sex to the job: jacks are for breeding programs, and a gelding gives you the size without the management.

Buying for conservation counts here. A Critical listing means every registered breeding animal matters, and an unregistered one, whatever its quality, does not move the breed's numbers.

Recent sale prices on HoofnHorn, where there are any, are further down this page.