Genetic characterization and differentiation of Indian sheep breeds using Microsatellite marker information

In this study the prevailing status of the genetic variability within and between two important sheep breeds - Marwari and Sonadi from Northwestern and and semi and region of India-was assessed using 25 Food and Agriculture Organization-International Society for Animal Genetics (FAO-ISAG) recommended microsatellite markers for ovines. All the markers were polymorphic in both breeds. Considerable high level of genetic variation was elucidated in the investigated breeds by allele diversity (Marwari = 6.24, Sonadi = 5.88) and gene diversity (Marwari = 0.683, Sonadi = 0.677). Genetic bottleneck was not detected in either of these sheep breeds. Overall positive F-IS value (0.129) and F-IT (0.179) > F-ST (0.058) indicated inbreeding to be one of the main cause for high genetic homogeneity and lack of heterozygosity in both breeds. Negative value of relatedness reflected influx of new germplasm in the investigated breeds. Low estimates of multilocus F-ST, low genetic distance measures (Nei's unbiased = 0.189) and high gene flow (Nm = 4.1) values implied low level of genetic differentiation between Marwari and Sonadi breeds. A correct breed assignment was possible for only 81 % of individuals. To combat high level of inbreeding and dilution in their genetic material, the present study suggested that concerted efforts are needed to generate awareness among farmers for the frequent exchange of rams between their flocks and maintenance of breed purity by use of selected rams of the specific breeds. The present information on diversity analysis can further be used to make assessment of genetic diversity and relationships between other indigenous sheep breeds - an important component of conserving genetic resources.