[Polymorphisms of insulin-like growth factor binding protein 3 gene and its associations with several carcass traits...

DNA samples from 60 Qinchuan cattle (Bos taurus) were analyzed with PCR-RFLPs and sequencing for insulin-like growth factor binding protein 3 (IGFBP3) gene. Fragments of 651 bp were amplified with two primers and the products of PCR were digested with restriction endonuclease HaeIII. The produced fragments showed three genotypes, namely AA,AB and BB after electrophoresis. Frequencies of the genotype AA,AB,BB and allele A,B were 0.7,0.28,0.02,and 0.84,0.16,respectively. Sequence analysis showed that a transversion of C-->A at 299 nt resulted in loss of the cleaved site of restriction endonuclease HaeIII and produced this polymorphism. This polymorphic locus of IGFBP3 gene was at Hardy-Weinberg equilibrium (P>0.05). The genotypes of AA,AB,BB slightly affected several slaughter and carcass traits of Qinchuan cattle. Dressing percentage,net meat percentage, striplion percentage, tenderloin percentage, ribeye percentage and tender shoulder percentage were decreased with the genotypes of AA,AB and BB in Qinchuan cattle, but it was not significant (P>0.05). Average ribeye area in individuals of AA genotype was significantly higher than that in individuals of BB genotype (P<0.05), and beef fat content in individuals of genotype AB and BB was significantly higher than that in individuals of AA genotype (P<0.01).