Khatib H, Huang W, Wang X, Tran A H, Bindrim A B, Schutzkus V, Monson R L, Yandell B S
Department of Dairy Science, University of Wisconsin-Madison, Madison 53706, USA.
J Dairy Sci. 2009 May;92(5):2238-47. doi: 10.3168/jds.2008-1767.
Decrease in fertility and conception rates is a major cause of economic loss and cow culling in dairy herds. Conception rate is the product of fertilization rate and embryonic survival rate. Identification of genetic factors that cause the death of embryos is the first step in eliminating this problem from the population and thereby increasing reproductive efficiency. A candidate pathway approach was used to identify candidate genes affecting fertilization and embryo survival rates using an in vitro fertilization experimental system. A total of 7,413 in vitro fertilizations were performed using oocytes from 504 ovaries and semen samples from 10 different bulls. Fertilization rate was calculated as the number of cleaved embryos 48 h postfertilization out of the total number of oocytes exposed to sperm. Survival rate of embryos was calculated as the number of blastocysts on d 7 of development out of the number of total embryos cultured. All ovaries were genotyped for 8 genes in the POU1F1 signaling pathway. Single-gene analysis revealed significant associations of GHR, PRLR, STAT5A, and UTMP with survival rate and of POU1F1, GHR, STAT5A, and OPN with fertilization rate. To further characterize the contribution of the entire integrated POU1F1 pathway to fertilization and early embryonic survival, a model selection procedure was applied. Comparisons among the different models showed that interactions between adjacent genes in the pathway revealed a significant contribution to the variation in fertility traits compared with other models that analyzed only bull information or only genes without interactions. Moreover, some genes that were not significant in the single-gene analysis showed significant effects in the interaction analysis. Thus, we propose that single genes as well as an entire pathway can be used in selection programs to improve reproduction performance in dairy cattle.
繁殖力和受孕率下降是奶牛场经济损失和奶牛淘汰的主要原因。受孕率是受精率和胚胎存活率的乘积。识别导致胚胎死亡的遗传因素是从群体中消除这一问题从而提高繁殖效率的第一步。使用体外受精实验系统，采用候选通路方法来识别影响受精率和胚胎存活率的候选基因。使用来自504个卵巢的卵母细胞和来自10头不同公牛的精液样本共进行了7413次体外受精。受精率计算为受精后48小时分裂胚胎数占接触精子的卵母细胞总数的比例。胚胎存活率计算为发育第7天囊胚数占培养的胚胎总数的比例。对所有卵巢进行了POU1F1信号通路中8个基因的基因分型。单基因分析显示，GHR、PRLR、STAT5A和UTMP与存活率显著相关，POU1F1、GHR、STAT5A和OPN与受精率显著相关。为了进一步表征整个整合的POU1F1通路对受精和早期胚胎存活的贡献，应用了模型选择程序。不同模型之间的比较表明，与仅分析公牛信息或仅分析无相互作用基因的其他模型相比，通路中相邻基因之间的相互作用对繁殖性状变异有显著贡献。此外，一些在单基因分析中不显著的基因在相互作用分析中显示出显著影响。因此，我们建议单基因以及整个通路都可用于选择程序，以提高奶牛的繁殖性能。
