The value of indigenous knowledge of yak breeding and cross-breeding have been largely ignored in the assessment of the potential for pastoral development on the Tibetan Plateau. This article is based on first-hand information obtained from indigenous nomadic societies living in western Sichuan, and explores the traditional strategies and indigenous knowledge of the yak herders. The author elucidates the major challenges to take into account when the best aspects of these traditional systems are to be incorporated into modernization plans.

The yak (Bos grunniens) is a large, multipurpose, high-altitude mammal, the only species of bovine capable of adapting itself to the physical environment of the Tibetan Plateau. Western Sichuan, the eastern extension of the Plateau, is a heat-deficient zone, situated some 3000-3500m above sea level, which has 12.18 million hectares of rangeland available for grazing by animals. Sichuan is the third most important yak-breeding region in China, after Qinghai and Tibet, accounting for 26% of the total number of yaks in the country. (Wu 1997a: 132). The breeding and rearing of yaks is inextricably linked to life on the Plateau and the daily life of Tibetans. The various breeds of yak which exist today have been selected by local herders over a long period of time. In western Sichuan two types of yaks have been identified: the valley type ("Jiulong" yak) and the Plateau type ("maiwa" yak) (Cai 1989: 85).

Yaks and rangelands in western Sichuan (China). The yak is a unique animal which is endemic to the Tibetan Plateau; it is of vital importance to the survival of nomads in very cold environments. Photo: Ning Wu.

Traditional aims of yak breeding
Traditional yak breeding patterns may be seen as the result of adaptive responses of organisms and societies to current pressures and specific historical processes (Wu 1997b: 77). Two main aims in breeding and cross-breeding can be distinguished.

The first is to produce improved or cross-bred animals suited to the specific climatic requirements of a given area. Different regions present different ecological conditions and thus different grazing systems. Environmental conditions in southwestern Sichuan are characterized by steep gradients, large temperature differences between the floors and the peaks of valleys, and new alpine meadow. These geo-ecological conditions contributed to the emergence of transhumant systems, lack of communication, and dictated the local herders' selection of the Jiulong for cross-breeding.

In northwestern Sichuan, by contrast, the Plateau features numerous morasses or semi-boggy areas, highlands with gentle slopes, and broad valleys, creating an open topography. Because of the smooth topography, the seasonal migration of nomads is more horizontal than vertical. Under these nomadic conditions, yaks tend to migrate freely and bulls may move from one area to another. They mate with individual cows or even whole herds, which results in a degree of inbreeding between the various yak stocks and the blurring of any genetic differences between them (Cai and Wiener 1995: 25). In view of these geo-ecological and pure-nomadic conditions, the maiwa (Plateau type) yak was selected for this area.

Second, yaks are also bred in such a way that their productivity levels meet subsistence needs and market demands. Owing to the difference in life-style, the various groups of pastoralists have different aims in breeding or cross-breeding. For example, the people in northwestern Sichuan use yaks primarily for milk; the maiwa yaks produce relatively large quantities of milk, with a high butter-fat content.

The herdsmen in southwestern Sichuan, by contrast, live in an area where yak products are sought after in the marketplace, and they use their yaks mainly for their meat and wool (breast hair), and also as draught animals. The Jiulong yaks produce good meat and hair and are sturdy draught animals. Marketing requirements always determine the objectives of breeding or cross-breeding.

Pure breeding vs. cross-breeding
Whether a pastoral community opts for pure breeding and/or cross-breeding depends not only on the actual environmental circumstances, but also on their cultural traditions. It is interesting that the distribution of the valley-type yak and the Plateau-type yak mirrors the traditional distribution of the Kham Tibetan and the Amdo Tibetan. The central area of Jiulong yak distribution has for many centuries been the homeland of the Kham Tibetan people. Traditionally, they chose pure breeding as the main method for selection and even today cross-breeding is rarely practiced. This has to do with the topography of the area: high mountains with deeply incised valleys restrict the exchange of yaks.

The region of the Plateau-type yak distribution is inhabited by Amdo Tibetan who are thought to be the descendants of the ancient Qiang people of northern China. Owing to its geographical accessability, cross-border exchange or trading of yaks existed not only in the Amdo area itself but also between different ethnic groups. Moreover, bulls for breeding could easily be introduced from the adjacent areas suitable for crop cultivation. The historical migration of nomadic tribes, including the Qiang, Tibetan and Mongolian peoples, also introduced new yak breeds and promoted genetic exchanges. As a result, it is cross-breeding which is most often practiced in this region, and hybrids are very common.

Traditional breeding strategies
In the course of time, individual herdsmen in the pastoral societies in western Sichuan have acquired both the knowledge and the skills to improve the production characteristics of their yaks. The system of selection used in the breeding of the Jiulong yak is an example of traditional selection procedures (Cai 1989: 99).

Selection of female yaks (cows):
The criteria for female yak are focused mainly on reproduction. Female yaks which are of breeding age (4-5 years old) which have not produced a calf are removed from the breeding pool. Barren or non-pregnant female yaks between three and four and female yaks who do not demonstrate sufficient maternal instinct to look after their young are also removed.

Selection of male yaks (bulls):
The selection criteria for choosing males are more stringent than those for females. Herdsmen focus first on the bull's ancestors (parents), and only then on the bull itself. The criteria for selection may be summarized as follows:

Female (mother) :

• high milk yield
• good conformation (big body)
• tame and gentle
• two previous calves

Male (father) :

• rich, thick hair
• numerous descendants

Bull itself:

• rough bases of horns with a long distance between them
• wide horns which curve outward
• broad forehead, muzzle and mouth
• long, thin lips
• thick neck, high withers and wide brisket
• wide, flat back, joint and rump
• straight forelimbs and curved hind legs
• hairy tail and shrunken scrotum
• coat black, or black with a few white specks on the forehead and at the extremities of the body (legs, tail, etc.).

The selection of the bulls themselves is carried out in three stages: pre-selection at one year of age, a second selection from among the first group at the age of two, and a final selection at three or four years. Culled bulls are castrated, after which they either serve as draught animals or are used for meat. The herdsmen try to ensure that there are two or three successors to an excellent dominant bull.

Traditional practices for cross-breeding
Herdsmen have traditionally been encouraged to concentrate on those characteristics of the yak which provide the greatest economic return. The strengthening of yak productive potential usually entails genetic upgrading of indigenous breeds through the addition of high-yielding exotic stock.

In the yak distribution area in Sichuan, cross-breeding between yak and cattle dates back at least 3,000 years, when it was practiced by the Qiang people. Through a process of trial and error, local herders gradually identified cross-breeding between male cattle and female yaks as the ideal method, leading to hybrids (F1) called "pian niu". The male F1 hybrids are known as "dzo" and the female hybrids as "dzomo". The herdsmen discovered that these hybrids are characterized by male sterility, but that dzomo have the ability to reproduce. However, they found that when dzomo are then cross-bred with yaks, atavism occurs after five generations. My research shows that in northwestern Sichuan, cross-breeding is carried out for only two generations. The F2 animals, called "za niu", can be subdivided into "mao za" (the progeny of male yaks and dzomo) and "huang za" (the progeny of male cattle and dzomo). In order to maintain hybrid vigour, nomads in western Sichuan make use of the following traditional practices.

Eliminating "za niu":
This is the earliest traditional method of maintaining and developing stock. Only F1 animals are bred, and all of their progeny (za niu) are killed or, at any rate, eliminated. This method is designed to increase dzomo milk production, strengthen the availability of hybrid vigour, and prevent the degradation of hybrid quality.

Eliminating "huang za" and developing "mao za":
Instead of killing all of the za niu (F2), the herdsmen use a method based on cross-breeding F2 progeny of dzomo with yak bulls. These hybrids retain the adaptability and productivity of yaks better than the huang za, while hybrid vigour declines more slowly.

Major challenges and concluding remarks
Improving yak productivity through selection is of great importance to the people who depend on yaks for their livelihood. In the last three decades, many state yak-breeding programmes have been carried out which involve crossing 'improved' breeds of dairy, beef, and dual-purpose cattle with yaks. When these improved breeds were introduced and cross-bred with local yaks, however, the actual socioeconomic benefits remained marginal, because the animals which were introduced could not adapt to the harsh local conditions. Improved female cattle breeds cannot survive in typical yak country, and they are not mated to yak bulls to provide reciprocal crosses. Furthermore, even if they survived, the females of such breeds would not lactate well without supplementary feeding.

Yaks are acknowledged to be an integral part of nomadic economies on the Tibetan Plateau (Scholz 1995: 69; Wu 1997b: 68). And yet, there are several major challenges which systematic breeding programmes must take into account.

• Traditional Plateau societies are subsistence communities rather than profit-driven communities. Pastoralists strive to increase stock numbers, to provide a form of insurance against eventualities such as winter cold and drought. Herdsmen know that the larger the herd, the greater the chance that it can be rebuilt in case of losses. This means that maintaining or increasing the number of yaks always takes precedence over improvements in quality or productivity. This places considerable constraints upon the genetic selection of yaks (Cai and Wiener 1995: 35).

• Although pastoral societies have for thousands of years been developing indigenous knowledge concerned with breeding and cross-breeding along rational lines, this wealth of knowledge has not been recorded in such a way that it can easily be tapped by improvement programmes. When experts are called in, they are always outsiders, who are concerned mainly with so-called modern approaches. Participatory approaches to development are still virtually non-existent. The absence of the necessary performance and parentage records are the main obstacles to programmatic genetic selection by herdsmen in Sichuan.

• To the herders and other local people, the mere survival of yaks in harsh, even hostile, environments is of paramount importance—even more important than improving an isolated performance trait. Natural selection is still better able to accurately and effectively predict survival rates than any current procedure devised by man (Wu 1997a: 141). Outsiders, including researchers and administrators, tend to forget that their task is to enable the local people to secure their own livelihood for decades to come. This can be done by involving the nomads in the initial design of interventions, incorporating viable arguments into yak development projects, and ensuring that 'modern' techniques for breeding and cross-breeding are not simply introduced, but are evaluated in practice by the herdsmen themselves.

Dr Ning Wu
Associate Professor
Chengdu Institute of Biology
Chinese Academy of Science
P. O. Box 416
610041 Chengdu, Sichuan
P. R. China
Tel.: +86-28-522 9115.
Fax: +86-28-522 2753.
E-mail: cascib@public.sc.cninfo.net

References
- Cai, L. (1989) 'Yak of Sichuan'. Chengdu: Sichuan Nationality Publishing House (in Chinese).
- Cai, L. and G. Wiener (1995) The yak. Bangkok: Regional Office for Asia and the Pacific of the FAO of the United Nations.
- Scholz, F. (1995) Nomadismus--Theorie und Wandel einer sozio-ökologischen Kulturweise. Erdkundliches Wissen, Band 118. Stuttgart: Franz Steiner Verlag.
- Wu, Ning (1997a) 'Conservation of yak biodiversity and its development potential in western Sichuan, China', in D. Miller, S. R. Craig and G. M. Rena (eds) Conservation and management of yak genetic diversity. Kathmandu: ICIMOD.
- Wu, Ning (1997b) 'Indigenous knowledge and sustainable approaches for the maintenance of biodiversity in a nomadic society', Die Erde 128(1): 67-80.