Polymorphisms of and Genes and Their Effects on Milk Production Traits in Chinese Holstein Cows.

Our preliminary research proposed the cytochrome P450 family 7 subfamily A member 1 () and hydroxyacyl-coenzyme A dehydrogenase trifunctional multienzyme complex beta subunit () genes as candidates for association with milk-production traits in dairy cattle because of their differential expression across different lactation stages in the liver tissues of Chinese Holstein cows and their potential roles in lipid metabolism. Hence, we identified single-nucleotide polymorphisms (SNPs) of the and genes and validated their genetic effects on milk-production traits in a Chinese Holstein population with the goal of providing valuable genetic markers for genomic selection (GS) in dairy cattle, This study identified five SNPs, 14:g.24676921A>G, 14:g.24676224G>A, 14:g.24675708G>T, 14:g.24665961C>T, and 14:g.24664026A>G, in the gene and three SNPs, 11:g.73256269T>C, 11:g.73256227A>C, and 11:g.73242290C>T, in . The single-SNP association analysis revealed significant associations ( value ≤ 0.0461) between the eight SNPs of and genes and 305-day milk, fat and protein yields. Additionally, using Haploview 4.2, we found that the five SNPs of formed two haplotype blocks and that the two SNPs of formed one haplotype block; notably, all three haplotype blocks were also significantly associated with milk, fat and protein yields ( value ≤ 0.0315). Further prediction of transcription factor binding sites (TFBSs) based on Jaspar software (version 2023) showed that the 14:g.24676921A>G, 14:g.24675708G>T, 11:g.73256269T>C, and 11:g.73256227A>C SNPs could alter the 5' terminal TFBS of the and genes. The 14:g.24665961C>T SNP caused changes in the structural stability of the mRNA for the gene. These alterations have the potential to influence gene expression and, consequently, the phenotype associated with milk-production traits. In summary, we have confirmed the genetic effects of and genes on milk-production traits in dairy cattle and identified potential functional mutations that we suggest could be used for GS of dairy cattle and in-depth mechanistic studies of animals.