4 Yak

The yak (Bos grunniens), is a grazing animal that is accustomed to traveling great distances in a harsh environment. Nothing is known about when it was first domesticated, but there has probably been a close association between man and yaks ever since the first humans migrated into the high mountains of Asia.

Appearance and Size

Domesticated yaks are about the size of ordinary cattle and rarely exceed heights of 1.3 m at the shoulder. Their liveweight is generally 250-550 kg for the males and 180-350 kg for the females. They differ little from wild yaks except that they are smaller, have shorter and thinner horns, and may be rusty brown, black, silver grey, or piebald instead of black.† Often they have whitish spots on their faces.

The yak's hair is long, especially on the flanks, where it forms a shaggy fringe that often reaches the ground. This, together with an underlying layer of thick, fine wool, protects the animal from the bitter cold of its native region. The yak has an enormous tail with a brush of long hair coming from its root, which is rare in bovines.

Long extensions of the thoracic vertebrae give the yak shoulders that look like a hump, but this is different from the boneless hump in zebus. The body is long, short-legged, and compact, with particularly large forequarters because, like the bison, the yak has 14 or 15 pairs of ribs instead of the 13 of domestic cattle.

The horns spread outward and upward, and the head is held low, like that of the bison. While no hornless domestic yaks have been reported in Nepal, more than 90 percent of those found in Mongolia lack horns.

Distribution

Most yaks are found especially in the mountains and plateaus of Tibet and western China, however they occur from northern Afghanistan, Pakistan, India, and Bhutan to Mongolia, and the Soviet Union.

Status

There are more than one million domestic yaks in the world.

Habitat and Environment

In the Himalayas the domestic yak is almost always found above 2,000 m elevation. Males are sometimes brought as low as 1,700 m for mating with cattle (see chapter 6), but they do not fare well at such altitudes. In Mongolia and Buryatiya (U.S.S.R.), however, they are found as low as 1,500 m elevation.

 

Yak distribution. (after J. Bonnemaire, 1976)

The wild yak lives in desolate mountain areas at altitudes of 4,000-6,000 m. Its habitat is the alpine tundra and the cold desert regions of the northern part of the Tibetan plateau. These barren mountain regions are remote and at higher elevations than the zones of human habitation.

Biology

Yaks look ungainly, partly because they are covered with long hair, but they are agile climbers and can maneuver narrow mountain paths. Their long hair is one adaptation to the cold climate. Other adaptations are the small, compact scrotum of the male and udder of the female, the small teats (only 2-3 cm long) and covering of hair over the udder, and the covering of short hair over the muzzle, except just around the nostrils.

In early summer yaks graze the lush grass in valley bottoms, but for much of the year they live on dry, coarse mountain grass and for long periods obtain water by eating snow.

The gestation length is 258 days - slightly shorter than that of cattle.

Behavior

Domestic yaks are docile and easily managed.

Uses

Yaks are especially useful as riding and pack animals; they can manage loads of more than 150 kg. At altitudes up to 6,000 m they may carry a pack or a person at a steady pace for days and still remain in good condition. In some regions they are the only feasible pack animal. Yak bulls (generally castrated) are also used for plowing and for threshing grain.

Occasionally the yak is slaughtered for meat. The meat is particularly important in parts of the USSR and in Mongolia, where in the cold, high-altitude environments it reportedly costs only half as much to produce as beef.

In most areas milk production is an essential aspect of yak husbandry. Yields vary considerably according to management and nutrition, but they average about 600 kg and can be more than 1,000 kg per lactation. Yak milk is golden colored. It is much richer than cow's milk; a typical analysis is: total dry matter, 17.35 percent; fat, 6.5 percent; protein, 5.3 percent; and sugars, 4.6 percent. The fat globules are much larger than those in cow's milk. People of Tibetan stock use yak butter as a food staple and as a lighting fuel.

Yak hide, though apparently not as good as that of cattle, is used for many purposes. It makes outstanding saddles. Yak hair is used for making ropes, saddle blankets (purportedly the best in the world), grainstorage bags, and tents. The fine wool that occurs beneath the long hair is used for making felt. The annual yield of adult females and males is about 750 g and 1,600 g of hair and about 350 g and 600 g of wool, respectively.

Because yaks are often found above the timberline their dung is an important fuel in many areas.

Advantages

Yaks can live and work hard in a cold climate. They are the only bovines to thrive at high altitudes. In cold, high areas they can work and produce meat and milk more efficiently and cheaply than cattle.

Limitations

Yaks are not well able to eliminate surplus heat because their heavy coat reduces their ability to sweat. In warm climates their respiration rate and body temperature increase and they become exhausted and susceptible to infections. At low altitudes in Nepal yaks die of a variety of diseases. Apparently not even yak-cattle hybrid animals (see next chapter) can successfully live below 700 m in that part of the world. This is probably due to overheating, since during the first half of this century yaks grew successfully in trials at low altitudes in Alaska and northern Canada.

Research and Conservation Needs

· Yak improvement programs are much needed. It seems probable that the genetic potential of the species is far from realized because Buddhist beliefs oppose the deliberate killing of stock. Techniques for deep freezing yak semen have been successfully developed at Regents Park Zoo, London and should prove invaluable for improving the breed.

· As a result of uncontrolled hunting the wild yak is endangered and is now restricted to remote barrens on upland plateaus and highlands in northern Tibet and Chinghai, inhospitable even to domestic yaks. The numbers of wild yak are unknown. They require total protection throughout their range and the establishment of adequately protected reserves with good pasture. To preserve their genetic purity, it is important to isolate wild yaks from domestic yaks and thus keep them pure.

· A primary need is to catalog the numbers and locations of purebred yaks. Today we have little idea of the total breeding population. Gathering such information is difficult, owing to the geographical isolation of the communities involved.

· It is also important to catalog the movement of yaks between different areas to see if enough genetic exchange occurs to prevent inbreeding of the population. Exchanges between local pastoralists were much more frequent in the past (for example, between Tibet and Nepal), but this is now more difficult because of border restrictions and because many yak

herders that used to move herds long distances have become sedentary farmers.

· Breeding strategies, herd management, product processing, and herd hygiene in Nepal, Bhutan, Sikkim, northern India, and northern Pakistan, Tibet, Mongolia, and the Soviet Union all differ greatly. It is important to get an overall perspective so that the strengths of the different systems can be judged and the weaknesses reduced.

· There are clearly different domestic yak "breeds" in terms of their appearance, and these need to be identified and compared systematically.

FIGURE