Power of microsatellite markers for analysis of genetic variation and parentage verification in sheep

We report the genetic analysis of 100 individuals of an elite breeding flock of Afshari sheep with a selected set of eighteen microsatellite markers. A full characterization of this set of eighteen loci was carried out generating allele frequency distributions that were used to estimate the genetic information content of these loci, including genetic variability, inbreeding, individual and parent verification parameters. Disregarding MCMA26 monomorphic pattern, microsatellite loci showed moderate level of polymorphism, as such totally 102 alleles were detected with a mean number of 6 alleles per locus. The average expected heterozygosity was 0.72 (SD = 0.07) and the average Polymorphism Information Content (PIC) was 0.67 (SD = 0.08). Total value of inbreeding based on marker data was estimated as -0.02 so it indicates that inbreeding occurred less than would be expected at random. The overall probability of identity considering all twelve independent loci combined was 3.148E-13 meaning lower than 1 in 31 trillions. The results of this study indicate, despite the selective breeding and closed flock system over a number of generations, a relatively high level of heterozygosity still exists in the representative sheep flock. The high degree of multiallelism and the clear and simple codominant Mendelian inheritance of the set of microsatellites used provide a powerful system for the unique identification of Afshari sheep individuals for fingerprinting purposes and parentage testing.