The Effect of Single Nucleotide Polymorphisms in the Tumor Necrosis Factor-α Gene on Reproductive Performance and Immune Function in Dairy Cattle

The present study aimed to assess the effect of polymorphisms in the tumor necrosis factor alpha (TNF-alpha) promoter (A/A, A/G and GIG) and exons (T/T, T/C and C/C) on immune function and reproductive performance in dairy cows. The occurrence of the first postpartum ovulation within 3 weeks in the cows with the TNF-alpha promoter A/G and G/G genotypes was higher than in the A/A group. Among the different TNF-alpha exon genotypes, the occurrence of early first postpartum ovulation was higher in the T/C and C/C genotype groups than in the TIT group. Single nucleotide polymorphisms (SNPs) in the TNF-alpha gene did not affect the rate of artificial insemination (AI) or duration from parturition to next conception (days open). The apoptosis rate of polymorphonuclear leukocytes (PMNs) did not differ among the TNF-a promoter genotypes, but the PMN transmigration rate was significantly higher for the A/A and A/G genotypes than for the GIG genotype. Interleukin 8 (IL-8) mRNA expression in PMNs and peripheral blood mononuclear cells (PBMCs) before culture was significantly higher for the A/A genotype compared with the GIG genotype. There were no significant differences between the genotypes in the mRNA expression of TNF-alpha, IL-6, IL-1 beta, and toll-like receptor 4 (TLR4) in PMNs and PBMCs before and 4 h after culture. IL-8 and IL-1 beta production by PBMCs cultured for 4 h was significantly higher for the animals with the A/A genotype than for those with the GIG genotype. On the other hand, no significant difference was observed in IL-8 and IL-1 beta production by PMNs among different TNF-a genotypes. Taken together, these results suggest that SNP in the TNF-alpha gene affects immune function and reproductive performance in dairy cows.