Chen Shi-Yi, Oliveira Hinayah R, Schenkel Flavio S, Pedrosa Victor B, Melka Melkaye G, Brito Luiz F
Department of Animal Sciences, Purdue University, West Lafayette, IN, 47907; Farm Animal Genetic Resources Exploration and Innovation Key Laboratory of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, 611130, China.
Department of Animal Sciences, Purdue University, West Lafayette, IN, 47907; Centre for Genetic Improvement of Livestock, Department of Animal Biosciences, University of Guelph, Guelph, ON, N1G 2W1, Canada.
J Dairy Sci. 2020 Nov;103(11):10383-10398. doi: 10.3168/jds.2020-18897. Epub 2020 Sep 18.
Milking speed (MS) and temperament (MT) are 2 workability traits of great importance in dairy cattle production and breeding. This is mainly due to an increased intensification of the worldwide production systems and greater adoption of precision technologies with less human-cattle interaction. Both MS and MT are heritable traits and thus, genomic selection is a promising tool to expedite their genetic progress. However, the genetic architecture and biological mechanisms underlying the phenotypic expression of these traits remain underexplored. In this study, we investigated the association of >5.7 million imputed whole-genome sequence variants with MT and MS in 4,381 and 4,219 North American Holstein cattle, respectively. The statistical analyses were performed using a mixed linear model fitting a polygenic effect. We detected 40 and 35 significant SNPs independently associated with MT and MS, respectively, which were distributed across 26 chromosomes. Eight candidate genes (GRIN3A, KCNJ3, BOSTAUV1R417, BOSTAUV1R419, MAP2K5, KCTD3, GAP43, and LSAMP) were suggested to play an important role in MT as they are involved in biologically relevant pathways, such as glutamatergic synapse, vomeronasal receptor and oxytocin signaling. Within their coding and upstream sequences, we used an independent data set to further detect or validate significantly differentiated SNP between cattle breeds with known differences in MT. There were fewer candidate genes potentially implicated in MS, but immunity-related genes (e.g., BOLA-NC1 and LOC512672), also identified in other populations, were validated in this study. The significant SNP and novel candidate genes identified contribute to a better understanding of the biological mechanisms underlying both traits in dairy cattle. This information will also be useful for the optimization of prediction of genomic breeding values by giving greater weights to SNP located in the genomic regions identified.
挤奶速度（MS）和性情（MT）是奶牛生产和育种中两个非常重要的可操作性性状。这主要是由于全球生产系统集约化程度提高，以及更多地采用了减少人与牛互动的精准技术。MS和MT都是可遗传的性状，因此，基因组选择是加速其遗传进展的一种有前景的工具。然而，这些性状表型表达背后的遗传结构和生物学机制仍未得到充分探索。在本研究中，我们分别在4381头和4219头北美荷斯坦奶牛中，研究了超过570万个推算的全基因组序列变异与MT和MS的关联。使用拟合多基因效应的混合线性模型进行统计分析。我们分别检测到40个和35个与MT和MS独立相关的显著单核苷酸多态性（SNP），它们分布在26条染色体上。八个候选基因（GRIN3A、KCNJ3、BOSTAUV1R417、BOSTAUV1R419、MAP2K5、KCTD3、GAP43和LSAMP）被认为在MT中起重要作用，因为它们参与了生物学相关途径，如谷氨酸能突触、犁鼻器受体和催产素信号传导。在它们的编码和上游序列中，我们使用一个独立数据集，进一步检测或验证了已知MT存在差异的奶牛品种之间显著分化的SNP。与MS潜在相关的候选基因较少，但在本研究中验证了在其他群体中也鉴定出的免疫相关基因（如BOLA-NC1和LOC512672）。鉴定出的显著SNP和新的候选基因有助于更好地理解奶牛这两个性状背后的生物学机制。这些信息对于通过对位于已鉴定基因组区域的SNP赋予更大权重来优化基因组育种值预测也将是有用的。
