Genetic Effect Analysis Of Candidate Gene Of Milk Production Traits And SNPs Screening In Chinese Holstein And Xinjiang Brown Cattle

In this study, we screened SNPs which was based on our previous results of the DNA mixed pool of Chinese Holstein and Xinjiang Brown Cattle population in Xinjiang, and conducted further research and analysis, detect verification and its Polymorphism, and also associate analysis was carried out on the milk production traits and somatic cell division(SCS)of Chinese Holstein and Xinjiang Brown Cattle in Xinjiang in order to find out molecular markers associated with milk production traits.First of all, appropriate SNPs were screened from DNA mixed pool results according to related reports about candidate gene of milk production traits; Chinese Holstein and Xinjiang Brown Cattle population in four cattle farm in Xinjiang were used in this study, and ultimately selected 21 SNPs according to the testing requirements of Mass Array technology and conducted individual genotyping experiments(including eight of which are provided by mixed pool, 13 refer to the relevant papers) on them.Secondly, 21 SNPs were genotyped by using Mass Array technology and 17 SNPs were selected to carried out a traits association analysis with milk production traits and SCS traits.The results of single marker association analysis showed that 12 SNPs have a different digrees of association with milk fat percentage, milk protein percentage, lactin percentage,total solid and SCS traits of Chinese Holstein Cattle and 15 SNPs have a different digrees of association with 305 days milk yield, milk fat percentage, milk protein percentage, lactin percentage, total solid and SCS traits of Xinjiang Brown Cattle; there are eight common SNPs associated with milk production traits and SCS traits of both Chinese Holstein and Xinjiang Brown Cattle, these SNPs are as following: Hapmap30646-BTC-002054 b,Hapmap30086-BTC-002066 ab, rs41586699, rs41624797, rs41627764, rs41647754,rs41941646 and rs41942492, respectively.Linkage disequilibrium test results showed that the five sites Hapmap30086-BTC-002066 ab, Hapmap30646-BTC-002054 b, rs29018751, rs41942492 and rs42954630 were in strong linkage disequilibrium, and the other two sites C60625677 T and rs41647754 were in a weak linkage disequilibrium. Further haplotype analysis showed that haplotype were composed by Block1 and Block2 was significantly associated with milk protein percentage and SCS traits of Chinese Holstein cattle; haplotype were composed by Block1 and Block3 was significantly or highly significantly associated with total solid and SCS traits of Xinjiang Brown Cattle.In summary, results in this study provide a theoretical basis and reference for the molecular marker-assisted breeding which is based on genome-based analysis in Chinese Holstein and Xinjiang Brown Cattle.