Introduction: The Yak as a Subject of Scientific Writing

Introduction

The yak (Poephagus grunniens) belongs to the tribe/family Bovin/Bovidae with the bison (Bison), buffalo (Bubalus) and cattle (Bos), and is the only species of the genus Poephagus. Linnaeus (1766) named the domestic yak as Bos grunniens for its distinctive vocalization and to indicate its relationship to cattle. More recently, the yak has been placed into its own genus Peophagus to emphasize its difference from other bovines. The yak is a multipurpose species and an indispensable livestock for the highlands of central Asian countries situated between 70o and 115o of east longitude and between 27° and 55° of north latitude. Thanks to its thick hide, subcutaneous fat layer, and dense hair, yaks survive the extremely cold weather (Fig. 1).

Figure 1. Yak herds stay outdoors all-year round in the pasture, including in the snow at night as shown.

Because of its large heart, lungs and a high erythrocyte count, the yak can tolerate the low oxygen content in the air of high altitude. Since it is the sole animal species of economic importance which can work at cold, high mountains as a pack animal (Fig. 2 and Fig. 3) and produce valuable products such as milk (Fig. 4), meat, hide, hair and dung, yaks play an important role in the local economy of the central Asian mountainous regions. The recent trend of the yak population decreasing at an alarming rate has become a serious concern to local yak users, concerned government officials and those who promote the conservation of animal genetic diversity. Since their habitats, particularly those of the wild type animal, are cold, desolate and isolated areas, the yak remains one of the most neglected ungulate species.

Figure 2. Yaks are used for transportation of goods.

Figure 3. Yaks are used for farm transportation.

Figure 4. Milking yaks.

The yak population worldwide is estimated to be about 14 million, distributed in China, Mongolia, Southern Russia, Tajikistan, Kirgies, Nepal, Bhutan, Myanmar, Pakistan and Afghanistan, of which 85% is located in China.

The yak is indeed the only large domestic animal which populates the central Asian Highlands up to altitudes of 6000m. It is therefore of extreme economic importance, providing the indigenous nomads and farmers with the essentials for their livelihood. Milk, dairy products (Fig. 5) and meat are the main foodstuffs. Skin, wool and dung are utilized to meet requirements for shelter, housing and fuel. The animals are also used in farming and transportation of goods. Yaks thus have a crucial role in the economy of peoples in the region.

Figure 5. Cheese making from yak milk.

The relative isolation of yaks in the mountainous regions of central Asian is illustrated by the dearth of writing about the yak in the West until relatively modern times. Currently, apart from much documentation of the yak by Chinese authors and a substantial body of publications in Russian, there are only a few books [1-3] and papers written in English, dealing with the Yak, especially about its reproduction. Much of the wealth of articles in scientific journals, reports and proceedings of technical meetings are mainly in Chinese or Russian languages and are not accessible to international communities. It should be mentioned that publications of the three international congresses on yak (1997 in Lanzhou, Gansu; 1999 in 1ining, Qinghai; 2000 in Lhasa, Tibet) [4-6] would be of great help to readers who are interested in yak production in Asian highlands.

The present book has been developed to fill gaps in knowledge and understanding, worldwide, and is intended not only for those concerned with the science of animal production, but also those with an interest in the biology of the yak. The editors recognize the IVIS’s Recent Advances Series as the best vehicle to distribute such information to veterinary clinicians, biologists and students. The book is entitled "Recent Advances in Yak Reproduction" and aims to give an account of the current knowledge, new findings and techniques on all aspects of yak reproduction. Attempts have been made to keep a balance between the fundamental details and useful practical information. We, as editors, kept our interference within the limits of usefulness, without overstepping our role, and we express our thanks to the contributors for their collaboration when asked for clarification, improvement and amendment.

Regarding the reference list for each chapter, the general trend has been to provide selected articles and reviews to enable the reader to consult the literature. However, the difficulties of translating Chinese into English may mean that some of the names of authors and titles and sources in the reference list may not be totally correct in every detail, and that some of the references listed will be difficult to access.