Study on Single Nucleotide Polymorphism of Gene and Its Correlation with Dairy Quality Traits of Gannan Yak.

This study explored the polymorphism of the leucine aminopeptidase () gene and its relationship with milk quality characteristics in Gannan yak. A cohort of 162 Gannan yak was genotyped utilizing the Illumina Yak cGPS 7K BeadChip, and the identified single nucleotide polymorphisms (SNPs) were evaluated for their association with milk protein, casein, lactose, and fat concentrations. The results showed that four SNPs (g.4494G > A, g.5919A > G, g.8033G > C, and g.15,615A > G) in the gene exhibited polymorphism with information content values of 0.267, 0.267, 0.293, and 0.114, respectively. All four SNPs were in Hardy-Weinberg equilibrium ( > 0.05). The g.4494G > A and g.5919A > G SNPs were significantly associated with protein content ( < 0.05), with homozygous genotypes showing significantly higher protein content than heterozygous genotypes ( < 0.05). The g.8033G > C SNP was significantly associated with casein content, protein content, non-fat solids, and acidity ( < 0.05), with the CC genotype having significantly higher casein, protein, and non-fat solids content than the GG and GC genotypes ( < 0.05). The g.15,615A > G SNP was significantly associated with average fat globule diameter ( < 0.05). In general, the mutations within the gene demonstrated a positive impact on milk quality traits in Gannan yak, with mutated genotypes correlating with enhanced milk quality. These results indicate that the gene could be a significant or candidate gene affecting milk quality traits in Gannan yak and offer potential genetic markers for molecular breeding programs in this species.