Abstract：
Milk production traits as the most important economic traits of dairy cows, they directly reflect the benefits of breeding and the economic benefits of pasture. In this study, A disintegrin and metalloproteinase-12 (ADAM12), Parkinson\'s disease gene 2 (PRKN) and dipeptidyl peptidase-like protein subtype 6 (DPP6) polymorphism in 384 Chinese Holstein cows were detected by time-of-flight mass spectrometry and through statistical analysis using software such as Popgene 32, SAS 9.4 and Origin 2022, the relationship between single nucleotide polymorphisms (SNPs) of three genes with four milk production traits such as daily milk yield (DMY), milk fat percentage (MFP), milk protein percentage (MPP) and somatic cell score (SCS) was verified at molecular level. The results showed that four polymorphic loci (116,467,133, 116,604,487, 116,618,268 and 116,835,111) of DPP6 gene, two polymorphic loci (97,665,052 and 97,159,837) of PRKN gene and two polymorphic loci (45,542,714 and 45,553,888) of ADAM12 gene were detected. PRKN-97665052, DPP6-116467133, ADAM12-45553888, DPP6-116604487 and DPP6-116835111 were all in Hardy-Weinberg equilibrium state (p > .05). ADAM12-45542714, PRKN-97159837 and PRKN-97665052 were moderately polymorphic (0.25 ≤ PIC <0.50) in Holstein. It is evident that the selection potential and genetic variation of these five loci are relatively large, and the genetic richness is relatively high. The correlation analysis of different genotypes between these eight loci and milk production traits of Holstein showed that ADAM12-45542714 and DPP6-116835111 (p < .01) had an extremely significant effects on the DMY of Chinese Holstein in Ningxia, while PRKN-97665052 had an extremely significant effect on MFP (p < .01). The effect of PRKN-97665052 and DPP6-116467133 on MPP of Holstein were extremely significant (p < .01). DPP6-116618268 had an extremely significant effect on the SCS of Holstein in Ningxia (p < .01), and AA genotype individuals showed a higher SCS than GG genotype individuals; the other two loci (ADAM12-45553888 and DPP6-116604487) had no significant effects on milk production traits of Holstein (p > .05). In addition, through the joint analysis of DPP6, PRKN and ADAM12 gene loci, it was found that the interaction effect between the three gene loci could significantly affect the DMY, SCS (p < .01) and MPP (p < .05). In conclusion, several different loci of DPP6, PRKN and ADAM12 genes can affect the milk production traits of Holstein to different degrees. PRKN, DPP6 and ADAM12 genes can be used as potential candidate genes for milk production traits of Holstein for marker-assisted selection, providing theoretical basis for breeding of Holstein.
摘要：
产奶性状作为奶牛最重要的经济性状,它们直接反映了育种的效益和牧场的经济效益。在这项研究中,解整合素和金属蛋白酶-12（ADAM12），通过飞行时间质谱检测384头中国荷斯坦奶牛的帕金森病基因2（PRKN）和二肽基肽酶样蛋白亚型6（DPP6）多态性，并使用Popgene32，SAS9.4和Origin2022等软件进行统计分析，三个基因的单核苷酸多态性（SNP）与日产奶量（DMY）等四个产奶性状之间的关系，乳脂百分比（MFP），在分子水平上验证了乳蛋白百分比（MPP）和体细胞评分（SCS）。结果表明,DPP6基因的4个多态位点(116,467,133,116,604,487,116,618,268和116,835,111),检测到PRKN基因的两个多态位点(97,665,052和97,159,837)和ADAM12基因的两个多态位点(45,542,714和45,553,888)。PRKN-97665052、DPP6-116467133、ADAM12-45553888、DPP6-116604487和DPP6-116835111均处于Hardy-Weinberg平衡状态(p>.05)。ADAM12-45542714、PRKN-97159837和PRKN-97665052在荷斯坦为中等多态性(0.25≤PIC<0.50)。很明显，这五个基因座的选择潜力和遗传变异相对较大，遗传丰富度相对较高。对这8个位点不同基因型与荷斯坦产奶性状的相关性分析表明,ADAM12-45542714和DPP6-116835111(p<.01)对宁夏荷斯坦的DMY有极显著的影响,而PRKN-97665052对MFP有极其显著的影响(p<0.01)。PRKN-97665052和DPP6-116467133对荷斯坦的MPP影响极显著(p<0.01)。DPP6-116618268对宁夏荷斯坦地区南海的影响极显著(p<0.01),AA基因型个体比GG基因型个体表现出更高的SCS；另外两个基因座（ADAM12-45553888和DPP6-116604487）对荷斯坦的产奶性状没有显着影响（p>.05）。此外,通过对DPP6、PRKN和ADAM12基因位点的联合分析,结果发现，三个基因位点之间的相互作用效应可以显著影响DMY，SCS（p<0.01）和MPP（p<0.05）。总之,DPP6、PRKN和ADAM12基因的几个不同位点对荷斯坦奶牛产奶性状有不同程度的影响。PRKN,DPP6和ADAM12基因可作为荷斯坦产奶性状的潜在候选基因，用于标记辅助选择，为荷斯坦病育种提供理论依据。
