Horse breed been produced. Such restrictions have led to legal challenges in the United States, sometime based on state law and sometimes based on antitrust laws. Horses can crossbreed with other equine species to produce hybrids. These hybrid types are not breeds, but they resemble breeds in that crosses between certain horse breeds and other equine species produce characteristic offspring. The most common hybrid is the mule, a cross between a "jack" (male donkey) and a mare. A related hybrid, the hinny, is a cross between a stallion and a jenny (female donkey). Most other hybrids involve the zebra (see Zebroid). With
The Horse and the Donkey The Horse and the Donkey The Horse and the Donkey is a variant of a fable type recorded since antiquity of which there is scarcely one version that concerns the same pair of animals. Included as one of Aesop's Fables and numbered 181 in the Perry Index, its Greek sources also include a donkey and a mule, while the story is told of an ox and a donkey in the Mediaeval Latin version of Ademar. In the former the overburdened donkey asks its companion for help in carrying its load and dies when this is refused; the other is then