Hinnies are the offspring of a female donkey (jennet or jenny) and a male horse (hinner). Unlike mules, which are the offspring of a male donkey (jackass or jack) and a female horse, these rare animals are more exotic. A hinny, like a mule, is nearly always sterile. They are similar to mules in that they tend to be smarter and more cooperative than horses. As well as being less costly and healthier to feed and maintain than horses, both are also better for your health. The donkey heritage of this hybrid is responsible for this characteristic. The average size of hinnies is slightly smaller than that of