Genetic variants of fatty acid elongase 6 in Chinese Holstein cow.

In the dairy industry, genetic variants have contributed to the improvement of milk production traits. Fatty acid elongase 6 (ELOVL6), which elongates saturated fatty acids (SFAs) and monounsaturated fatty acids (MUFAs), plays a distinct role in the balance of long-chain fatty acids composition in animals. ELOVL6 catalyzes the elongation of palmitic acids (C16:0) which is the most common saturated fatty acid found in animals and also an essential precursor to synthesize other long-chain fatty acids. However, the genetic variant research of bovine ELOVL6 on milk quality traits is still unknown. Therefore, our study aimed to detect the single nucleotide polymorphism (SNPs) of bovine ELOVL6 and explored the relationship between SNPs and milk quality traits including milk yield, fat content, protein content and somatic cell score. In this study, three SNPs, including SNP1 (g16379651A>G), SNP2 (g16458976A>G) and SNP3 (g16511290A>G), have been identified in intron 3 and 3'UTR regions of ELOVL6 in Chinese Holstein (CH) cows. Besides, the results of genetic diversity analysis, linkage disequilibrium and haplotype analysis indicated that these SNPs presented moderate polymorphisms which reflected relatively high genetic diversity. No strong linkage among these SNPs were detected in sampled population of cows. Moreover, the results of correlation analyses demonstrated that these SNPs of bovine ELOVL6 were significantly related to milk yield (P < 0.05). The SNP1 was also correlated with somatic cell score, whereas the SNP3 was associated with fat content. The 21 combined genotypes (diplotypes) were highly significantly correlated (P < 0.01) with milk yield. These results revealed that the genetic variants of bovine ELOVL6 influenced the milk production of CH cows. Hence, the three SNPs could be regarded as molecular markers in marker-assisted selection (MAS) of the dairy cow breeding.