A Relationship Between Genotypes At MyoD And DGAT1 Loci And Carcass Traits In Cattles

The polymorphisms of MyoD, myf 5 and dgat1 in catties including three Chinese breeds (Luxi cattle, Jinnan cattle and qinchuan cattle) and four cross-breeding populations · (Limousin×Luxi cattle, Simmental×Luxi cattle, Charolais×Luxi cattle and Angus×Luxi cattle) were detected by PCR-SSCP and PCR-RFLP technologies. The associations between these polymorphisms and some cattle carcass traits were analyzed using the SPSS general linear model (GLM). Results were obtained as follows:A 261bp sequence of bovine MyoD gene intron 2 was cloned; there are no similarities between the cloned sequence and human MyoD gene. Two SSCP alleles (named allele A and allele B) of MyoD intron 2 were detected, which caused by C→T at 39bp and C→G transition at 112bp. Only two genotypes A A and AB occurred in the population .In Chinese local cattle B allele was dominant allele, and this locus was at Hardy-weinberg equilibration except for CharolaisxLuxi cattle and AngusxLuxi cattle. Statistical analysis revealed significance effect of genotypes on the living weight, carcass weight and loin eye area, the value of individuals with genotypes A A was higher than AB (p<0.05or p<0.01).Only three genotypes AA, AB and BB occurred in the population, which caused by A→G transersion at 1948bp of myf5 gene intron 2 PCR product digested by TaqI was detected. In the population it was not at Hardy-weinberg equilibration (p<0.05or p<0.01). The analysis results showed: no significant association between genotypes and carcass traits except for net meat weight.Four SSCP alleles at DGAT1 gene 3'UTR product were detect out in experimental populations, and five polymorphic sites were found, The alleles were named A, B, C and D. The PIC was 0.71 at this locus in Luxi cattle. In the studied population, the locus was not at Hardy-weinberg equilibration (p<0.05or p<0.01). Some significant differences were observed among DGATl AA, AB, BB, CC and CD cattle genotypes. Homozygous BB in the group significant higher than CC on the living weight, carcass weight, net meat weight, loin eye area, whereas marbling, back fat and intramuscular fat content was lower (p<0.05) in BB than CC (p<0.05).The polymorphism of PCR-SSCP was not inspected in the MYOG exon 1 of bovine.Further studies on a bigger population size are needed to confirm the observed effect of MyoD, MYF5, MYOG and DGAT1 genotypes on carcass quality traits.