Polymorphisms And Association With Lactating Performance Of Leptin In Chinese Holstein Cows

Leptin is the hormone product of the leptin gene in the adipose tissue. The association of the leptin single nucleotide polymorphisms with uberty, milk yield, SCC, milk protein percent and so on, had been confirmed. And then we carried further study on the association between the leptin gene SNPs and the Lactating Performance in Chinese Holstein cows. The results were as follows:The polymorphisms of E2JW and E2FB of leptin exon 2 were detected and the genotypes were isolated by PCR-RFLP in 190 Chinese Holstein cows. And then the effects of the two SNPs on Lactating Performance were analyzed with a Mixed Model by software SAS 8.2 using DHI data. Besides, the polymorphisms of leptin promoter were detected by PCR-SSCP in the same cows. Then, five kinds of genotypes (AA, AB, AC, BB, BC) and three kinds of alleles (A: 528C-617G-618C, B: 528C-617A-618T, C: 528T-617G-618C) were found after sequencing in present study. And the polymorphism of PSD, which was 617G/A-618C/T, was discovered for the first time and the polymorphism of UASMS2 (528C/T ) was detected in the same while. In present research groups, the effects of the polymorphisms of UASMS2 and PSD on the Lactating Performance were also analyzed by the same data statistical method as the above. Results demonstrated that:E2JW SNP of leptin exon 2 was significantly associated with the Milk Fat Percent (P=0.02) and the 305 Days Milk Yield (P=0.03), and E2FB was significantly associated with the Milk Protein Percent (P=0.04). Then, the crossing effects of the two SNPs, E2JW and E2FB, were analyzed and the results were found. The differences were significant for 305 Days Milk Yield between the cows with the genotype MN*PP and MM*PQ or and MM*QQ (P<0.05). And the differences were also significant for the character between the cows with the genotype NN*PQ and MM*PP, MM*QQ or and MN*QQ (P<0.05). But there were no associations of the crossing effects with the Milk Fat Percent, the Milk Protein Percent and the SCC (P>0.05).And a significant association was found with the305 Days Milk Yield (P<0.05) of leptin promoter polymorphisms studied in present research. And a significant difference was also found for the Milk Fat Percent between the cows with the genotype BC and AB (P=0.03), or and BB (P=0.04). Besides, another significant difference was found for the 305 Days Milk Yield (P<0.05) between the cows with the genotype BC and AB (P=0.008), AC (P=0.005), or and BB (P=0.01). But there were no significant association between the polymorphisms and the Milk Protein Percent or and SCC in the cows.So, E2FB polymorphism of leptin exon 2 could be considered as the genetic molecular marker for the 305 Days Milk Yield and the Milk Fat Percent, and E2JW polymorphism as the marker for the Milk Protein Percent in the Chinese Holstein cows. And the crossing effects of E2FB and E2JW polymorphisms were significantly associated with the 305 Days Milk Yield (P=0.045). UASMS2 and PSD polymorphisms of leptin promoter could be considered as the genetic molecular markers for the 305 Days Milk Yield and the Milk Fat Percent.