On the breeds of cattle: Their history, classification and conservation

Abstract

Cattle are kept worldwide in various environments and play many different roles in our society. We have analyzed the genetic diversity of cattle by combining zoological, archaeological, historical, topographical, agricultural and molecular-genetic data, This provides context and arguments for answering our main question: how do individual breeds contribute to the cattle genetic resources? This question is most relevant for the conservation of the cattle genetic resources In Chapter 2 we review the zoological origin of domestic cattle, which descends from a number of cross-fertile bovine species. Chapter 3 investigates the dynamic history of cattle and the several parallels with human history: their domestication, worldwide dispersal, differentiation into hundreds of regional adapted types and, since the industrial revolution, the development of specialized, highly productive breeds. These are now replacing many locally adapted breeds. There is a major concern that this leads to an erosion of the cattle genetic resources. The appendices of Chapter 3 illustrate that the history of breeds has been most complex with crossbreeding being the rule rather than exception and a never-ending development of new synthetic breeds. This demonstrates that any assessment of cattle genetic diversity represents only a snapshot of a continuously changing situation. Classifications of breeds are essential to understand the present genetic diversity. In Chapter 4 the many classification of cattle since the 19th century are examined. Since none of these are satisfactory, our Cattle Breed Encyclopedia presented in 1995 is a systematic and comprehensive classification, which was slightly revised in 2011. Our scheme integrates regions of origin, history and morphology and correlates well with a biochemical classification from 1980 and a recent DNA-based classification of the European breeds. Topographic maps showing the region of origin of over 1500 breeds and exports from Europe, Asia and Africa to America make up the atlas in Chapter 5. This geographic exposition shows several patterns that help to understand the current diversity at the global, continental or national level. To define better the role of breeds in conservation, we refine in Chapter 6 the categorization of breeds on the basis of their history as it is used by the FAO. Integrating this with the results from Chapters 2-5 we arrive at the following conclusions: - The many breeds worldwide still represent an appreciable diversity of adaptation, morphology and performance. - Replacement of locally adapted breeds by highly productive exotic breeds is the most urgent threat of cattle genetic resources. - Cattle breeds with a high genetic diversity, ancestry of exotic bovine species or unique adaptive, productive or morphological traits obviously contributes to the overall diversity. - Even if the disappearance of a breed would not decrease significantly the available diversity, this breed still is a unit of management. Thus, breeds contain a portion of the genetic resources that is either specific for the breed or shared by other breeds. Separate management maintains independent development of breeds and is instrumental for the conservation of the diversity.