Genetic characterization of sheep breeds based on protein polymorphisms

Abstract

A total of 381 Suffolk, Ile de France, Poll Dorset, Santa Ines and crossbred sheeps was used to investigate variability, genetic relationship, and the efficiency of protein polymorphisms in racial characterization and parentage tests. The genetic characterization was done through electrophoresis and by isoelectric focusing. The investigated loci presented 64.7% of variability. Two new alleles of Hemoglobin, HbA1 and HbB1, were detected in Santa Ines, Suffolk and crossbred animals. The allele M of glucose phosphate isomerase is, probably, a genetic marker for the Suffolk breed. The values of Nei’s Diversity for the leucine amino peptidase, nucleoside phosphorilase, hemoglobin and malic enzyme loci were higher than the others, indicating higher specificity in sheep breed characterization. Fisher’s test revealed that allelic frequencies were different among breeds (P<0.01), with the exceptions of the alleles phosphogluconate dehydrogenase and Catalase loci (P>0.05). This genic differentiation was confirmed by multivariate analysis, which dendrogram, constructed from the genetic distances, showed two main clusters: one clusters the wool and the other the hairy breeds. In the first cluster, two distinct subgroups are observed: one represented by the specialized breeds Poll Dorset and Ile de France, and the other represented by the Suffolk group, demonstrating the genetic relationships among breeds. The efficiency of these markers to exclud one of two possible sires was 76.7, 68.0, 61.3 and 84.8 % for the Poll Dorset, Ile de France, Suffolk and Santa Ines breeds, respectively. The inclusion of other markers will increase the efficiency to 100% and will allow greater precision in investigation of paternity