Kumaresan A, Johannisson Anders, Al-Essawe Essraa M, Morrell Jane M
Department of Clinical Sciences, Division of Reproduction, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
Department of Clinical Sciences, Division of Reproduction, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden.
J Dairy Sci. 2017 Jul;100(7):5824-5836. doi: 10.3168/jds.2016-12484. Epub 2017 May 3.
The accurate prediction of bull fertility is of major economic importance in the dairy breeding industry. Sperm fertilizing potential is determined by their ability to reach the oocyte, complete fertilization, and sustain embryogenesis, which is partly determined by the quality of sperm DNA. In the present study, we analyzed several sperm functions required for fertility, including DNA damage, in frozen-thawed spermatozoa of breeding bulls with different adjusted nonreturn rates (NRR56), and identified a suitable combination of parameters that could be used to predict bull fertility. Based on the NRR56, bulls were classified into below- and above-average fertility, a total of 37 characteristics of spermatozoa were evaluated for each bull, and their relationship with bull fertility was studied. Of the different sperm functional attributes, differences were observed in sperm viability, acrosomal integrity, reactive oxygen species, and DNA fragmentation index (%DFI) among below-average, average, and above-average fertility bulls. Principal component analysis also revealed that sperm viability, acrosome status, reactive oxygen species, and %DFI were the important variables, having highest correlation with NRR56. Our results indicated that the proportion of live [correlation coefficient (r) = 0.53] and live acrosome-reacted spermatozoa (r = 0.50) were significantly positively related to NRR56, whereas the proportion of dead spermatozoa (r = -0.53) and %DFI (r = 0.61) were significantly negatively related to NRR56 in bulls. Linear regression analysis indicated that a combination of live [coefficient of determination (R) = 0.72], dead (R = 0.72), live hydrogen peroxide-negative spermatozoa (R = 0.64), and %DFI (R = 0.56) could differentiate below-average and above-average fertility bulls, and thus were considered for development of a fertility prediction model. The accuracy of the developed model for fertility prediction in bulls was high (R = 0.83). We concluded that flow cytometric detection of sperm viability, hydrogen peroxide status, and %DFI could discriminate below- from above-average fertility bulls.
准确预测公牛生育力在奶牛育种行业具有重大经济意义。精子的受精潜力取决于其到达卵母细胞、完成受精以及维持胚胎发育的能力，而这部分取决于精子DNA的质量。在本研究中，我们分析了不同调整后不返情率（NRR56）的种公牛冻融精子中生育所需的几种精子功能，包括DNA损伤，并确定了可用于预测公牛生育力的合适参数组合。根据NRR56，将公牛分为生育力低于平均水平和高于平均水平两组，对每头公牛的37种精子特征进行评估，并研究它们与公牛生育力的关系。在不同的精子功能属性中，观察到生育力低于平均水平、平均水平和高于平均水平的公牛在精子活力、顶体完整性、活性氧和DNA碎片化指数（%DFI）方面存在差异。主成分分析还表明，精子活力、顶体状态、活性氧和%DFI是重要变量，与NRR56的相关性最高。我们的结果表明，活精子比例[相关系数（r）=0.53]和活的顶体反应精子比例（r = 0.50）与NRR56显著正相关，而死精子比例（r = -0.53）和%DFI（r = 0.61）与公牛的NRR56显著负相关。线性回归分析表明，活精子[决定系数（R）= 0.72]、死精子（R = 0.72）、活的过氧化氢阴性精子（R = 0.64）和%DFI（R = 0.56）的组合可以区分生育力低于平均水平和高于平均水平的公牛，因此被考虑用于建立生育力预测模型。所建立的公牛生育力预测模型的准确性很高（R = 0.83）。我们得出结论，通过流式细胞术检测精子活力、过氧化氢状态和%DFI可以区分生育力低于平均水平和高于平均水平的公牛。
