Abstract
The maternal effect has been widely proposed to affect the production traits in domestic animals. However, the sequence polymorphisms of mitochondrial DNA (mtDNA) and association with milk production traits in Holstein cows have remained unclear. In this study, we investigated the single nucleotide polymorphisms (SNPs) of mtDNA ATPase 8/6 genes and association with four milk production traits of interest in 303 Holstein cows. A total of 18 SNPs were detected among the 842 bp fragment of ATPase 8/6 genes, which determined six haplotypes of B. taurus (H1-H4) and B. indicus (H5-H6). The mixed model analysis revealed that there was significant association between haplotype and 305-day milk yield (MY). The highest MY was observed in haplotype H4. However, we did not detect statistically significant differences among haplotypes for the traits of milk fat (MF), milk protein (MP), and somatic cell count (SC). The overall haplotype diversity and nucleotide diversity of ATPase 8/6 genes were 0.563 ± 0.030 and 0.00609 ± 0.00043, respectively. The results suggested that mitochondrial ATPase 8/6 genes could be potentially used as molecular marker to genetically improve milk production in Holstein cows.
Notes
Notes: The haplotype diversity, nucleotide diversity, and average number of nucleotide differences were denoted by h, π, and k, respectively. The Tajima's D was only estimated in the 237 samples of B. taurus.
Note: Values are presented by the least squares means ± standard error. ns, not significant. The superscripts lacking a common lowercase differ significantly (P < 0.05). MY = 305-day milk yield; MP = Milk protein concentration; MF = Milk fat concentration; SC = Somatic cell count. The sample numbers of haplotypes, herds, and parity are listed in the brackets.
Y.-H. Qin and S.-Y. Chen contributed equally to this study.