a domestic animal; the hybrid offspring of a horse (mare) and an ass (jackass). The mule has characteristics of both parents. It has the size and swiftness of the mare. From the jackass it inherits hardiness and a capacity for work exceptional for its size. The mule is known for its long life-span (as long as 40 years) and low susceptibility to illness. It does not require special feed or maintenance. The mule is almost always sterile. Some instances have been recorded in which the mating of a female mule with a stallion or jackass has resulted in offspring. The general color of the mule is determined by the mare.
Mules are classified according to work capacity as pack or draft animals. Pack mules are 110–140 cm high at the shoulders, and draft mules up to 160 cm. Pack mules weigh 300–400 kg, and draft mules 400–600 kg. A mule can pull 18–20 percent of its weight, depending on the nature of the load and the individual characteristics of the animal. All males are castrated between the ages of 1½ and two years. Mules are first trained for work at the age of two; they carry a full load after four years of age. Mule raisers house the young and adult animals under the same conditions as horses.
Mules are widely used in Asia, Southern Europe, and North and South America. In 1960–65 the world’s mule population was 13.8 million, and in 1971, 14.7 million. In the USSR, mules are raised in Transcaucasia and Middle Asia. On Jan. 1, 1941, there were 6,300 mules in the USSR, in 1965, 3,400, and in 1971, 3,200.