Molecular Identification And Application Of Polled Trait In Yunling And Xianan Cattle

Horn development is a common phenomenon in the bovine family,the horn is a derivative of the skin morphologically.The results of the study on bovine polled gene showed that P_F represented polled gene of origin in Holstein cattle,which indicated that 5candidate mutations including three SNPs and two Indels formed a haplotype block?PG1654405A,PC1655463T,PC1768587A,P5ID and P80kbID?.The polled gene originated from Celtic culture area is P_C,containing a haplotype P_202ID.Therefore,these six loci can be used to distinguish horned and polled cattle.At present,the research on the bovine polled gene limited to the European and American cattle breeds,and the research on the native Chinese cattle is rare.In the study,a total of 250 polled Yunling cattle,13 horned Yunling cattle,127polled Xianan cattle and 20 horned Xianan cattle were selected to investigate the polled cattle genes in Yunling cattle and Xianan cattle and the gene frequency and genotype frequency of polled genes.The clear pedigree of Yunling and Xianan cattle shows that these two breeds are not Friesian origin and not carry P_F.Therefore,in this study,PCR and PCR-RFLP method were used to detect the polled gene P_C of Yunling and Xianan cattle and analysis the genotypic and allelic frequency of the polled genes in Yunling cattle and Xianan cattle,which founding a molecular genetics basis of identification and culturing polled Yunling and Xianan Cattle.The new results were as follows:?1?The haplotype P_202ID were detected in Yunling and Xianan cattle,and the polled gene is P_C.?2?In Yunling cattle,the frequency of polled genotype P_C/P_C was 18.63%.The frequency of heterozygous polled genotype P_C/p_rs was 63.50%in Yunling cattle and the total frequency of polled genotypes was 82.13%in Yunling cattle.The frequency of recessive homozygous genotype p_rs/p_rs was 1.90%in Yunling cattle.The success rate of molecular identification of horned and polled traits in Yunling cattle was 84%?221/263?.?3?In Xianan cattle,the frequency of polled genotype P_C/P_C was 4.08%,the frequency of P_C/p_rs was 82.31%,and the frequency of p_rs/p_rs was 13.61%.The success rate of molecular identification of horned and polled traits in Xianan cattle was 100%.?4?In this study,eight horned Yunling cattle were identified as heterozygous genotype(P_C/p_rs)with the frequency of 3.04%;Thirty-four polled Yunling cattle were identified as horned genotype(p_rs/p_rs)with frequency of 12.93%;In addition,16%?42/263?of Yunling cattle had a genotype inconsistent with both horned and polled traits,suggesting that Yunling cattle with indicine ancestry may have non taurine polled mutation.?5?The breeding program of the polled strains of Xianan and Yunling cattle was developed.