| Summary: | Effective conservation strategies for livestock populations will require breeds to be characterized on the basis of their genetic attributes. Genetic markers can be used to survey breed relationships and within-breed population structure. They can also be used for the identification of breeds. In this study markers were used to investigate genetic relationships among thirty-seven European cattle breeds. Blood group (A,B,C,F,L,S,Z) and serum protein (transferrin and albumin) polymorphisms in 18,859 animals were analysed. French, Italian and Channel Island breeds were found to have generally higher heterozygosities and greater numbers of alleles than breeds from Britain and Northern Europe. Genetic distances among breeds were estimated, and two major breed groups were identified. French, Italian and Channel Island breeds clustered together in one group, while the second group consisted of breeds from Britain and Northern European. All breeds were significantly different from one another (p < 0.0001). In general, relationships among breeds reflected their geographical origin and common ancestry, rather than the agricultural use for which the breeds have been selected. Genetic markers provide a potentially powerful way of identifying the breed of individual animals. Microsatellite markers were found to be more powerful than diallelic markers for distinguishing among breeds, approximately one microsatellite to six diallelic markers was required to achieve the same power of discrimination. The number of markers needed to achieve a given error rate could be reduced by selecting the most discriminatory individual markers. However, the exact number of markers required depends on the number and type of breeds to be identified. The development of new DNA technologies is making screening of large numbers of loci economically viable, which will enable genetic differences between breeds to be more precisely understood and their genetic histories to be more accurately defined.
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