Study On Relationship Between Polymorphism Of DGAT1, LOX-1 Gene And Milk Production In Chinese Holstein

The DGAT1 gene and LOX-1 gene were studied using PCR-SSCP and PCR-RFLP in one hundred and forty-six Chinese Holstein and analyzed the genetic variation. The relationship between genetic markers and the milk production were analyzed. The aim was to explore perfect markers which can provide theoretical base for breeding in dairy cattle. The results were follows:1. The analysis on polymorphism and sequence on the 3'untranslated region of DGAT1 geneThree genotypes KK, MM and KM were found in PCR amplification region of the premier DGAT1P1 in Chinese Holstein, and the genotype frequency were 0.2977, 0.0534, 0.6489 in Chinese Holstein. Sequence for the region demonstrated that there were lots of mutations. There were two mutation with 11 992 bp and 11 993 bp (GT→CA) in the KK and MM genotype. The position of 11 989 bp (T→G) in the KK genotype was mutation.2. The analysis on polymorphism and sequence on the 5'flank region of DGAT1 geneThree genotypes AA, BB and AB were found in PCR amplification region of the premier DGAT1P2 in Chinese Holstein, and the genotype frequency were 0.1027, 0.3904 and 0.5068. At the position 3 272 bp (T→C) was a mutation in the AA genotype. There were two mutations with the position 4263 bp (added G) and 4 346 bp (T→C) in the BB genotype. At the position 7 174 bp was added a C in the BB genotype.3. The analysis on polymorphism and sequence on the exon VIII of DGAT1 geneThree genotypes KK, AA and KA were found in PCR amplification region of the premier DGAT1P5 in Chinese Holstein, and the genotype frequency were 0.1164,0.3562,0.5274. The study found a nonconservative substitution of lysine by alanine (K232A) in DGAT1 caused by an adenine/adenine to guanine/cytosine at position 10 433 and 10 434, respectively, in exon VIII.4. The analysis on polymorphism and sequence on the 3'untranslated region of LOX-1 geneThree genotypes AA, BB and AB were found in PCR amplification region of the premier LOXP1 in Chinese Holstein. The genotype frequency was 0.1374, 0.3130 and 0.5496. There was one mutation with the position 892bp (C→T) in the AA genotype. The position of 900bp (T→G) in the BB genotype was mutation.5. The relationship between the polymorphism and milk production traitsWe chose the DGAT1 gene and LOX-1 gene as candidate gene to study milk production traits in Chinese Holstein. The study showed that in DGAT1P1 amplified fragment, there were highly significant effect between different genotypes in protein content and fat content (P<0.01 or P<0.05), ME in BB genotypes significantly higher than that in AB and AA genotypes (P<0.05). No significant effect of different genotypes on their SCS (Somatic Cell Score) was found. In DGAT1P2 amplified fragment, there were highly significant effect between different genotypes in fat content (P<0.05), and no significant effect of different genotypes on their ME and protein content. In LOXP1 amplified fragment, there were highly significant effect between different genotypes in fat content (P<0.05), and no significant effect of different genotypes on their ME and protein content. So DGAT1 gene and LOX-1 gene were suit to be MAS of Chinese Holstein.