Study On Genes Variations Determining Marbling Score Using Microsatellite Markers And DNA Pooling In 8 Cattle Breeds

In this study, we combined 7 microsatellite loci associated with marbling score (BM1258, BM9138, BMS468, ILSTS026, BMS2780, BR2936, BMS779) in 8 cattle breeds (Holstein, Simmental, Red Steppe, Limousin, Luxi cattle, Bohai Black cattle, Japanese Black Cattle, Angus cattle) with DNA pooling analytical technique to study the relationship among the polymorphism of each microsatellite markers, varieties similarity coefficient and the genetic distances. In order to produce the snowflake beef, the cattle varieties were predicted based on the character homogenicity principle.The results showed that a total of 63 alleles were identified and averaged about 9 in each loci. The largest number of loci is BM9138 which has 13 alleles and the least is BMS779 and BMS468 for 6.All those indicate that there is much rich polymorphism information in the 7 microsatellite loci we chose, which can be used for genetic variation analysis. Specific alleles were found in Bohai Black cattle,Japanese Black Cattle, Luxi cattle and Limousin cattle. ILSTS026 loci (150 bp), BM9138 loci (170 bp、168 bp) and BMS2780 loci (120 bp) specific alleles were existed in Bohai Black cattle, ILSTS026 (158bp) specific allele was existed in Japanese Black Cattle, BMS779 loci (183bp) specific allele was existed in Luxi cattle, ILSTS026 (156bp,152bp) specific alleles were existed in Limousin cattle, and BMS468 (124bp) specific allele was existed in Red Steppe.There were 334 alleles for 7 microsatellite loci in 8 breeds. For 7 microsatellite loci, Bohai Black cattle had the most alleles, 52; Holstein cows is least for 30; then Simmental 44; Red Steppe 47; Limousin 43; Luxi cattle 43; Japanese Black cattle 37; and Angus 38. Bohai Black cattle has high genetic variation and rich polymorphism,they need protection and utilization for precious germplasm resources.The average genetic distance between populations was 0.200505 (0.094737 to 0.275). The least genetic distance is 0.094737 between Luxi cattle and Bohai Black cattle; and Limousin and Japanese Black Cattle’s genetic distance is 0.275 that is the largest. The similarity coefficients of Japanese Black Cattle between Holstein, Angus and Bohai Black cattle were all greater than 0.8, but smaller than 0.8 between other breeds. So we can infer that Japanese Black Cattle had high similarity with Holstein, Angus and Bohai Black cattle for beef marbling score. The results of cluster analysis by MEGA4 software using the neighbor-jioning method and unweighted pair-group method with arithmetic means method are basically the same: Holstein cows and Japanese Black cattle were clustered into one class, and then Luxi cattle and Bohai Black cattle were clustered, Simmental and Limousin were clustered.The results of cluster analysis by MEGA4 software using the neighbor-jioning method, Limousin and Simmental was first clustered together, and then was clustered with Red Steppe; Bohai Black cattle was clustered with Luxi cattle,these 5 breeds were classified one group. Holstein cows was clustered with Japanese Black cattle,then was clustered with Angus ,they were classified one group. The dendrogram can reflect the geographical distribution, meat feature, genetic differentiation characteristics and genetic relationship of 8 breeds clearly and objectively.According to our research and foreign cross combinations practice, meanwhile think from the character homogenicity of marble, in order to resolve the source shortage of beef in our country, we advise to put Japanese Black cattle, Angus, Holstein, Bohai Black cattle as parents to crossbreeding produce the best beef.