Kasimanickam R, Nebel R L, Peeler I D, Silvia W L, Wolf K T, McAllister A J, Cassell B G
Department of Large Animal Clinical Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA.
Theriogenology. 2006 Sep 15;66(5):1307-15. doi: 10.1016/j.theriogenology.2006.04.025. Epub 2006 Jun 21.
The objective was to evaluate the relationship of a competitive index (CI) determined by heterospermic performance and post-thaw semen quality of the same stored ejaculates. Semen from multiple ejaculates collected in succession from each bull (four Holstein and four Jersey) was pooled. Heterospermic doses (20x10(6)/straw) were made to obtain all possible Holstein-Jersey combinations (16 two-bull combinations) and contained 20x10(6) sperm/mL/bull. Cows at two University dairy farms were inseminated on observed or synchronized estrus. The sire of calves (N=460) were determined and a CI was determined for each bull (based on the number of calves sired). Prior to preparation of the heterospermic doses, a sub-sample of semen from each bull was taken, processed, frozen, and stored concurrently with heterospermic samples. Post-thaw semen samples (homospermic) from each bull were assessed for: sperm morphology, acrosome integrity, sperm motility parameters assessed by computer assisted sperm analysis (CASA), flow cytometry analysis of DNA Fragmentation Index (DFI), and Plasma Membrane Integrity (PMI). Heterospermic performance of Holstein bulls was superior to that of Jersey bulls. The DFI was negatively correlated to CI (r=-0.87; P<0.001), whereas the PMI (r=0.87; P<0.001) and total progressive motility (r=0.74; P<0.05) assessed by CASA were positively correlated to CI. In multivariate regression models, the DFI and PMI accounted for 87% variance in competitive index. In conclusion, bulls with less DFI and higher PMI had higher probabilities of siring calves.
目的是评估由异种精子受精性能所确定的竞争指数（CI）与相同储存射精后的解冻精液质量之间的关系。将从每头公牛（四头荷斯坦奶牛和四头泽西奶牛）连续采集的多次射精的精液进行混合。制备异种精子剂量（20×10⁶/细管）以获得所有可能的荷斯坦 - 泽西组合（16种双公牛组合），且每种组合中每头公牛的精子浓度为20×10⁶/mL。两所大学奶牛场的母牛在观察到发情或同期发情时进行授精。确定了犊牛（N = 460）的父亲，并为每头公牛确定了一个竞争指数（基于所产犊牛的数量）。在制备异种精子剂量之前，从每头公牛采集一份精液子样本，进行处理、冷冻，并与异种精子样本同时储存。对每头公牛解冻后的精液样本（同种精子）进行以下评估：精子形态、顶体完整性、通过计算机辅助精子分析（CASA）评估的精子活力参数、DNA碎片化指数（DFI）的流式细胞术分析以及质膜完整性（PMI）。荷斯坦公牛的异种精子受精性能优于泽西公牛。DFI与CI呈负相关（r = -0.87；P < 0.001），而通过CASA评估的PMI（r = 0.87；P < 0.001）和总渐进性运动能力（r = 0.74；P < 0.05）与CI呈正相关。在多变量回归模型中，DFI和PMI解释了竞争指数中87%的方差。总之，DFI较低且PMI较高的公牛产犊的概率更高。
