Classification of cattle breeds contributes to our understanding of the history of cattle and is essential for an effective conservation of genetic diversity. Here we review the various classifications over the last two centuries and compare the most recent classifications with genetic data. The classifications devised during the 19th to the late 20th century were in line with the Linnaean taxonomy and emphasized cranial or horn morphology. Subsequent classifications were based on coat color, geographic origin or molecular markers. Several theories were developed that linked breed characteristics either to a supposed ancestral aurochs subspecies or to a presumed ethnic origin. Most of the older classifications have now been discarded, but have introduced several Latin terms that are still in use. The most consistent classification was proposed in 1995 by Felius and emphasizes the geographic origin of breeds. This is largely in agreement with the breed clusters indicated by a biochemical and molecular genetic analysis, which reflect either groups of breeds with a common geographic origin or single breeds that have expanded by export and/or crossbreeding. We propose that this information is also relevant for managing the genetic diversity of cattle.

Cattle are our most important livestock species because of their production and role in human culture. Many breeds that differ in appearance, performance and environmental adaptation are kept on all inhabited continents, but the historic origin of the diverse phenotypes is not always clear. We give an account of the history of cattle by integrating archaeological record and pictorial or written sources, scarce until 300 years ago, with the recent contributions of DNA analysis. We describe the domestication of their wild ancestor, migrations to eventually all inhabited continents, the developments during prehistory, the antiquity and the Middle Ages, the relatively recent breed formation, the industrial cattle husbandry in the Old and New World and the current efforts to preserve the cattle genetic resources. Surveying the available information, we propose three main and overlapping phases during the development of the present genetic diversity: (i) domestication and subsequent wild introgression; (ii) natural adaptation to a diverse agricultural habitat; and (iii) breed development.

Several studies have investigated the differentiation of mitochondrial DNA in Eurasian, African and American cattle as well as archaeological bovine material. A global survey of these studies shows that haplogroup distributions are more stable in time than in space. All major migrations of cattle have shifted the haplogroup distributions considerably with a reduction of the number of haplogroups and/or an expansion of haplotypes that are rare or absent in the ancestral populations. The most extreme case is the almost exclusive colonization of Africa by the T1 haplogroup, which is rare in Southwest Asian cattle. In contrast, ancient samples invariably show continuity with present-day cattle from the same location. These findings indicate strong maternal founder effects followed by limited maternal gene flow when new territories are colonized. However, effects of adaptation to new environments may also play a role.

SUMMARYFocusing on cattle (Bos taurus, Bos indicus), the present paper discusses the concept of the breed in the context of the dynamic history of livestock domestication. A breed categorization is proposed on the basis of how the breeds came into existence. The online Appendix (available at http://journals.cambridge.org/AGS) presents a survey of the cattle breeds of the world consisting of: (1) a list of breeds per country and then subdivided according to the proposed categories; (2) a list of breed names, including synonyms and translations, ordered according to a comprehensive breed classification; and (3) an alphabetical list of these names. The commonly accepted perceptions of breeds and how these are influenced by the nomenclature are described. Considering the history of breeds, it is argued that conservation of genetic diversity does not necessarily imply conservation of breeds. However, breeds are instrumental for the conservation of genetic diversity as independent genetic management units. These considerations may very well be extrapolated to other domestic species.

The available data on the domestication and history of cattle are summarized in this chapter, including the appearance of phenotypes that today are the subject of genetic research. Focus is given on taurine cattle spread over the old world, zebus around the equator, large taurines during classical antiquity, small cattle in medieval Europe, modernization of cattle husbandry and industrial cattle, crossbreds and local breeds.