Analyse Genetic Structure And Variation Of Sheep Populations For Meat Production Using Microsatellite DNA

Hybrid is a main measure to improve the meat production of sheep in practice. The analysis of genetic structure and genetic variation and calculation of genetic distance between populations provide the premise of predicting heterosis and selecting better hybrid parents.In the study, five microsatellite loci which are located in different chromosome and have high polymorphism were used to analysis the genetic structure and genetic variation of five sheep breeds. The gene frequency and genotype frequency of five populations in the five loci were analysed using Chi-square test. The result showed that these five populations lies in Hardy-Weinberg equilibrium state. The number of alleles, range of the mean polymorphism information content,number of effective alleles and the heterozygsity in the population calculated from genie frequency were 12-14,0.64-0.79,3.48-5.41 and 0.69-0.81 respectively in these loci. This showed that five microsatellite loci in five populations had the high polymorphism, and so, there was a large selection potential in sheep parent population.Moreover, the genetic distance between populations were calculated using method of Nei's standard genetic distance m. Among the distances between the abroad breeds and Xiao Wei Han sheep(Han), the breeds order from the large to small was White-Suffolk(0.7462) > Black-Suffolk(0.7334) > Dorset(0.6983) > Texel(0.6439).The distance torder from large to small between each abroad breeds was between Black-Suffolk and Texel(0.7854), between White-Suffolk and Texel(0.6804), between Dorset and T-exel(0.5305), between Dorset and Black-Suffolk(0.3693) .between Black-Suffolk and White-Suffolk(0.2994) ,and White-Suffolk and Dorset(0.2801).The clustering dendrograph was drawn by using UPGMA method from genetic distance of five populations and four populations. The two kinds of results all clearly showed the geographical distribution, the feature of genetic differentiation and the relationship between five sheep populations. Also, it provided the basis for selecting better sire breeds used in hybrid and improvement of Small Tail Han sheep and for predicting heterosis and actual crossing effects.