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Summary Microsatellite variation was surveyed to determine the genetic diversity, population structure and admixture of seven North Ethiopian cattle breeds by combining multiple microsatellite data sets of Indian and West African zebu, and European, African and Near-Eastern taurine in genetic analyses. Based on allelic distribution, we identified four diagnostic alleles ( HEL1-123 bp, CSSM66-201 bp, BM2113-150 bp and ILSTS6-285 bp) specific to the Near-Eastern taurine. Results of genetic relationship and population structure analyses confirmed the previously established marked genetic distinction between taurine and zebu, and indicated further divergence among the bio-geographical groupings of breeds such as North Ethiopian, Indian and West African zebu, and African, European and Near-Eastern taurine. Using the diagnostic alleles for bio-geographical groupings and a Bayesian method for population structure inference, we estimated the genetic influences of major historical introgressions in North Ethiopian cattle. The breeds have been heavily (>90%) influenced by zebu, followed by African, European and the Near-Eastern taurine. Overall, North Ethiopian cattle show a high level of within-population genetic variation (e.g. observed heterozygosity = 0.659-0.687), which is in the upper range of that reported for domestic cattle and indicates their potential for future breeding applications, even in a global context. Rather low but significant population differentiation ( FST = 1.1%, P < 0.05) was recorded as a result of multiple introgression events and strong genetic exchanges among the North Ethiopian breeds. [ABSTRACT FROM AUTHOR]

Genetic diversity and conservation potential of six indigenous cattle breeds of north Ethiopia was analysed based on 20 microsatellite markers using core set methods. Expected future diversity (assuming assigned extinction probabilities are valid for the next 20–50 years) were 0.988 ± 0.011 and 0.980 ± 0.010 with expected loss of diversity estimated at 0.02% and 0.74% of current level for the Maximum Variance Total (MVT) and Maximum Variance Offspring (MVO) core sets, respectively. Even though all breeds have contributed to current diversity levels, the Afar and Abergelle breeds only contributed 51% and 62% to the MVT and MVO core sets, respectively, while the Raya breed contributed only 6% and 1.5% to the MVT and MVO core set diversities, respectively. Moreover, prioritizing the six north Ethiopian cattle breeds using the conservation potential obtained from the MVT core set method seems reasonable considering the origin and migration histories of the breeds. Our results suggest that the total current genetic diversity of these breeds can be sufficiently maintained by designing a conservation strategy based on conservation potential of each breed from the MVT core set so that priority is given to lowering the extinction probabilities of breeds with high conservation potential to zero. [ABSTRACT FROM AUTHOR]

Ethiopia is considered to be a putative migratory corridor for both Near-East Bos taurine and Arabian and Indian B. indicus cattle into East Africa. African pastoralism, which is associated with adaptation to specific habitats and farming systems, has contributed to the composite constitution of Ethiopian cattle. We analyse, for the first time, five Y-chromosome microsatellite markers from seven north Ethiopian cattle populations, using a European Holstein-Friesian population as a reference, to assess the paternal gene pool and to explore the mechanisms behind the genetic structure. Our results reveal that the indicine alleles predominate in the present populations, with only one animal in the Arado carrying the taurine alleles. The north Ethiopian cattle populations with one exception (Abergelle) are characterized by a general low Y-chromosome haplotype diversity, as well as by a reduced interpopulation variance (ΦST=4.0%), which can be a result of strong male-mediated selective sweeps. Population structure revealed by multidimensional-scaling analysis differentiates two populations (Arado and Abergelle) from the rest. Analysis of molecular variance does not lend support to the traditional classification for the populations, which is mainly based on physical characteristics. A network analysis indicates two closely related founding haplotypes accounting for a large proportion (50.0% in Abergelle and 85.0–94.7% in others) of north Ethiopian cattle Y-chromosomes. Our findings point to a common, but limited, paternal origin of the north Ethiopian cattle populations and strong male-mediated gene flow among them. The findings also provide insight into the historical immigration of cattle into East Africa.Heredity (2007) 98, 214–221. doi:10.1038/sj.hdy.6800931; published online 10 January 2007 [ABSTRACT FROM AUTHOR]