•  Miniature - up to 36"
•  Small Standard - 36" to 40"
•  Standard - 36" to 48"
•  Large Standard - 48" to 56" (jennets up to 54")
•  Mammoth Jack Stock - 54" & up for Jennets,  56" and up for Jacks/Geldings

• Mammoth Jackstock Jacks must measure no less than 14.2 hands in height, at least 61 inches around the heart girth, and at least 8 inches at the cannon bone (the narrowest point between front knee and fetlock.
• Mammoth Jackstock Jennets and geldings must measure no less than 14 hands in height, at least 61 inches around the heart girth, and at least 7.5 inches at the cannon bone (the narrowest point between front knee and fetlock.

At the very basic level, mammoth jackstock is a prey species and a herbivore. An animal in a natural environment that would have to be able to move around long distances and graze, be able to climb steep and rocky terrain, escape and fight predators, withstand environmental hazards and procreate on occasion.  No matter what we do, we have to keep in mind the original God given design.  On top of that we want our jackstock to be able to work, carry and pull loads, be healthy and sound and easy to maintain and have the disposition to want to accommodate us.

Understanding that there is a very important purpose behind the conformation standards is helpful in being able to perceive an ideal and using this mental template on the real thing.  It's rather like buying a pick up truck.  You want to know that the frame/chassis is strong enough to do the hauling or pulling, the engine has enough power to get you there.  Once you understand that it's able to perform as intended, then you can start looking at all the surface accessories (power door locks, chrome, c.d. player, etc...).

Jackstock are not  longeared horses.  They do not have the double muscling that horses do, and even have some subtle but unique skeletal differences.   Often people only see the outside of an animal - they see a round donkey and think it's the best, not because it's conformation is better (meaning it's skeletal structure) but it has more body fat, making it look fuller and more 'horse-like'.    Jackstock should not be shown like fat beef steers and should not be placed in halter classes according to fat content.   Conformation should be the all deciding factor - meaning body structure meant for function not just pretty.  Ultimately, if the function is there, the animal can't help but be beautiful.

Size is very important in Jackstock, however, extreme size should not placed over conformation and agility in your animals. Your best conformed jackstock are on the average found between 14.2hh and 15.2hh - taller animals, unless excellently bred, can loose structural stability.  Taking proper measurement means placing the animal on flat level ground, such as a poured concrete pad and using a measuring standard that has bubble levels to promote accuracy.  This measurement is taken when the animal is relaxed and standing square on all four feet,  with it's head and neck naturally raised.  The measuring cross bar is placed over the wither where it is touching the animal and their feet should be decently trimmed.  Especially long front feet with shoes on will give false measurements.  

No excellently conformed animal is a bad color.  However, great many colored animals can be VERY badly conformed.  Don't breed just for color - if the animal is unsound otherwise, don't breed it. Color blindness is something to be very wary of in yourself as a breeder.  

Choose your breedings where the jack and jennet compliment each other.  This means that they do not share the same faults - hopefully you get a blend of the best from each, but you should always look at what if you got the worst from each - would that be bad enough to not do the breeding? 
 

6yr old 14.3 hand mammoth jackstock jennet (Eclipse) demonstrating shoulder and hip angulations, length of back with neck tie in.  Photo by J. Rachau

Conformation Notes:

• Head & Ears - you don't ride the head but....  In order to survive and thrive properly the teeth need to be aligned.  An equines teeth continue to erupt and only constant grinding from the opposing teeth keep them in check.  Malocclusion is not something you want to be breeding for.  The head should be in proportion with it's body.  Jackstock naturally have a bigger head (wider through the crown and jaw especially) than a horse equal to it's size.  Straight or slight roman noses in Mammoths are not frowned on, the eyes should be large, well offset and prominent (Mammoths are allowed bony eye ridges though eyes should be large and expressive).  Ears should not lop, are upright and long.  Though exact inches are not critical, the pinna should just look like they fit to the head they are attached to.  Jackstock are admired for their large well carried ears.

• Neck - the neck is the balancing  power fulcrum for the body, it needs to be straight, strong and fairly long. It should rise well out of the top of the shoulder.  Low neck attachments usually go along with too steep shoulders and a front end, downhill stance. 

• Shoulder -- most focus on the degree of the shoulder angle only, I look at the entire shoulder, especially the length of the bone from the point of shoulder to the elbow (the humerus).  This is what gives your animal power and flexibility in the front end.  If they have a nice laid back shoulder and no humerus length then they really can't do much (rather like a model wearing a long narrow skirt and can only take tiny baby steps - it all looks nice but what can be practically done with it?) Look how everything ties in together rather than just the top angle of  the shoulder.

• Wither - -    For riding and performance stock I want an adequate wither.  Jackstock can be bred to have a saddle back.   They do not have to have table top straight back lines from neck to tail like a beef cow - personally I don't think it's very functional.  Look at any performance horse and you should get the idea - you need to have a wither for a good power attachment for the neck and back muscles.  I like my saddle staying put when I ride.

• Front legs - the joints should be in line over each other in a decently straight line from point of shoulder to hoof tip as seen from the front and side, this encourages straighter, efficient movement with less wear and stress on the joints. Leg length is important, I like to see enough leg under my donkeys, and even mini's should not have dwarfish stunted leg length for all their smallness.

6yr old 14.3 hand  jennet (Eclipse) demonstrating straight line from point of shoulder to tip of toe,  also exhibiting adequate breadth of chest.  Photo by J. Rachau

Chest - a donkeys should have sufficient width of chest so it doesn't appear that both front legs are coming out of the same hole. Back -  the back should be short for strength but remember because of the lack of a prominent wither the donkeys back can look LONGER than it really is.  The back should have a strong loin and smooth tie in to the croup and should also be fairly level from wither to rear (meaning the high point of the wither isn't much lower than the high point of the croup)  This means the mammoth isn't then built 'downhill' where the back end is much taller than the front, which is considered a weakness.   Hips - a smooth croup is always pleasing, but for me again the user ability is most important, and that is the DEPTH of the hip (from the side: Point of hip to Point of buttock) -  You can have the straightest top line with a high tail set and have the narrowest hip and butt which translates to lack of power. Don't get fixated on the top line totally, take into consideration the function and depth of the entire area.

Hind legs -  I want a good length with plenty of bone (not coarse, but solid).  Proportion and balance of bone length between each joint is critical.   The straightness of joints  in line as perceived from the back is again important for less wear and stress.  (When your jackstock is standing square in the back - are the cannon bones parallel?  Are the rear toes pointing forward? Very slightly toed out in the rear is normal, even in some performance horses.)  It can be forgiven if the donkey is close behind when standing as long as the cannon bones are parallel.   Often donkeys will stand under themselves slightly cowhocked - but when moving out, away from the viewer from behind,  they will be straight movers.   Hooves -   should be a good circumference for the size that he is, be oval or round, open and healthy.  The health of the foot can sometimes indicate the health of the animal overall.   Disposition - Always mammoth jackstock, no matter what gender, should be gentle, accommodating and willing to please - don't breed bad tempered animals - temperament will be passed on!

6yr old 14.3 hand  jennet (Eclipse) demonstrating straight line from point of buttock to heel.  Photo by J. Rachau

• Testicles - jacks should always have both testicles descended if they are to be bred.  A proven genetic train; cryptorchidism is a condition where one or both testicles fail to descend into the scrotum.   Such jacks should be castrated and not allowed to bred to keep this condition from being passed on.