Some background to the yak book was provided in the preface to the first edition and this is therefore reprinted below. The second edition represents an extensive revision of the chapters in the first edition and a substantial enlargement through the addition of five new chapters. Sadly, the death of Professor Cai Li in 1997 has meant that his expertise in what he termed "yakology" could not be brought to bear on the revision. Two scientists of a younger generation, eminent in their own specialist subjects but with a major involvement in yak research, have joined this endeavour from Gansu Agricultural University in northwest China - a university that stands in friendly rivalry, in its concern with yak, with the late Professor Cai Li's Southwest Nationalities College.
Apart from the continuing growth of the scientific literature on yak that has added to this edition, it had become apparent that two matters were insufficiently dealt with previously. One of these is the crucial role that culture and social context play in yak keeping. Although these issues were recognized and alluded to before, the topic has now been expanded into a new chapter. The second matter is the continuing search for the scientific basis underlying yak production. The subjects involved have become increasingly specialized and provide, for the present, perhaps more insights for the scientists than for practitioners of yak keeping - but they are the foundation for future developments. These issues and the understandings derived from them form the basis of three new chapters. The first of these looks in some detail at the alpine rangeland ecosystem and its management. The second deals with fundamental processes in yak nutrition, and the third is concerned with advances in the genetics of yak at the molecular and cytogenetic level.
The discussion of yak in different regions has been greatly enlarged into a chapter dividided into three parts. The first part provides information, for the first time in this book, on the special features of yak keeping in six provinces of China - the six that account for most of the yak in that country. The second part, revised and enlarged from an earlier chapter, provides much information on yak keeping and yak research in other countries that have a long history and tradition of yak keeping; this includes a new section that takes a broad sweep over yak in Western High Asia, and includes some of the more remote countries of the region with small but locally important yak populations. The section on Mongolia has been re-written by a new author; some of the others have been re-written or revised by their former authors or with new collaborators. It is a matter of regret that no one could be found willing to write on behalf of the countries of the Russian Federation (with the honourable exception of Buryatia) and that section is therefore based on available literature. The third part of this long chapter has been added to provide a little evidence on yak in countries with environments that are not traditional for yak - principally yak kept commercially in North America, as well as a few in Europe and elsewhere and yak kept in zoos and wild animal parks.
It is hoped, therefore, that the book will continue to appeal to those with an interest in yak but wishing to delve also a little below the surface. It is hoped also that the more esoteric science in the book will provide a review of the subjects treated for those with specialist interests and will be seen by general readers as showing how yak research is being integrated with that on other ruminants. An overview is provided at the start of each chapter for those who do not want the detail. As before, the concluding thoughts in the final chapter are written from my perspective as an outsider to the actual art of keeping yak. An "outsider's perspective" should at least have the merit of being in tune with one of the important aims of the book, which is to make knowledge of yak more widely accessible to the world outside the yak territories.
Much care has gone into the production of this volume and much help received (see acknowledgements to both editions). Inevitably, some inadequacies may remain. Some will be of our own making and some due to lack of information on certain points. Hopefully, such problems will be few compared to the wealth of information presented.