Polymorphism Of IGFBP-5 And MYOG Gene In Six Cattle Populations And Its Association With Body Measurement Traits

Chinese yellow cattles have some defects such as small physique, narrow hindquarter, etc. Because of the high heritability of body measurement traits and the association between body measurement traits and economic traits, it can improve the production performance of Chinese cattles by selecting the body measurement traits. 779 individuals from six populations (namely, Luxi,Nanyang,Jiaxian red,Xia'nan,Simmental×Luxi crossbred steers and Qinchuan) were selected to detect polymorphism of IGFBP-5 and MyoG gene by using PCR-SSCP and DNA sequencing technique, and to study its association with body measurement traits. The aim was to choose perfect markers which can provide theoretical base for breeding in Chinese cattle. The results were as follows:Only one sites existed polymorphism in IGFBP-5 gene and two sites in MyoG gene, which were exon 3 in IGFBP-5 gene and exon 1 and 3'UTR in MyoG gene. The analysis of association between different genotypes and body measurement traits were showed as follows:1 The polymorphism analysis of the exon 3 of IGFBP-5 geneA SNP of 3402 G→A in the exon 3 region of the IGFBP-5 gene was detected, and PCR-SSCP method was then developed to genotype all the individuals. Three genotypes AA, AB and BB were identified after PCR-SSCP. They were all at middle diversity; Theχ2-test showed that all populations besides Qinchuan cattle were at Hardy-Weinberg equilibrium (P > 0.05). Least squares analysis revealed that in all populations, animals with the AA genotype had higher mean values for hucklebone width than those with the BB genotype (P<0.05). In Qinchuan, Jiaxian red and Luxi populations, animals with AA genotype had higher mean values for chest circumference than those with the BB genotype (P<0.05). In Nanyang population, animals with AA genotype had higher waist height than those with BB genotype. In Luxi population, animals with AA genotype had higher body height than those with BB genotype.2 The polymorphism analysis of the exon 1 of MyoG geneThree genotypes (CC, CD, DD) were identified in exon 1 of MyoG gene in all population. Sequencing showed that allele D had a base mutation of T→C at the position of 314 bp (based on EF636458). According toχ2 test, we found out the locus of all populations besides Luxi, Nanyang and Qinchuan were in Hardy-Weinberg equilibrium (P>0.05). Association analysis of polymorphisms with body measurement traits shows that: in Luxi population, animals with the genotype CC have higher mean values for body length and rump length than those with the genotype DD (P<0.05); in Simmental×Luxi crossbred steers population, animals with the genotype CC and CD have higher mean values for waist height than those with the genotype DD (P<0.05), animals with the genotype CC have higher mean values for hucklebone width than those with the DD genotype (P<0.05); in Nanyang population, animals with the genotype CC have higher mean values for waist height and hucklebone width than those with the DD genotype (P<0.05); in Xia'nan population, animals with the genotype CC have higher mean values for hucklebone width and rump length than these with the genotype DD (P<0.05); in Jiaxian red population, animals with the genotype CC have higher mean values for rump length than those with the genotype DD (P<0.05); in Qinchuan population, animals with the genotype CC have higher mean values for waist height and rump length than those with the genotype DD (P<0.05).3 The polymorphism analysis of the 3'UTR of MyoG geneThree genotypes AA, AB and BB were identified after PCR-SSCP in exon 3 and 3'UTR of MyoG gene. Sequencing results showed that the mutation was 2109 A→G. Statistical analysis indicated that in all populations, animals with AA genotype have higher mean values for body length than those with the BB genotype (P<0.05); in Luxi population, animals with the AA genotype have higher mean values for rump length than those with the genotype BB (P<0.05); in Jiaxian red population, animals with the AA genotype have higher mean values for body height than those with the BB genotype (P<0.05).