Sub-fertility is a major problem in crossbred bulls. Identification of subtle differences in the quality of cryopreserved spermatozoa among bulls belonging to different fertility rankings would help determine the latent fertility of semen before their use at field conditions. In the present study, we assessed the status of tyrosine phosphorylation, membrane integrity and acrosome reaction of cryopreserved spermatozoa in crossbred bulls (n = 22) with different levels of field fertility and assessed their relationship with fertility. Bulls were categorized into above-average (n = 4), average (n = 14) and below-average (n = 4) based on their different field fertility rates. The progressive sperm motility was significantly (P < 0.05) higher in above-average fertile bulls compared to either average or below-average fertile bulls whereas sperm membrane integrity and acrosomal reaction status did not differ among the three groups. The proportion of live tyrosine-phosphorylated spermatozoa were significantly (P < 0.05) higher in below-average and average fertile bulls compared to above-average bulls. Immunolocalization of protein tyrosine phosphorylation in spermatozoa revealed that the proportion of spermatozoa showing tyrosine phosphorylation at acrosome and post-acrosomal area (APA) and at acrosome, post-acrosome and tail (APAT) were significantly (P < 0.05) higher in below-average fertile bulls than other groups. The APA pattern (r = -0.605; P < 0.01) and APAT (r = 0.507; P < 0.05) pattern were significantly and negatively correlated with bull fertility. It was concluded that the proportion of live tyrosine-phosphorylated spermatozoa in cryopreserved semen was negatively related to bull fertility.

中文翻译：

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冷冻保存精液中酪氨酸磷酸化精子的比例与杂交公牛的生育能力呈负相关

低生育率是杂交公牛的主要问题。鉴定属于不同生育力等级的公牛冷冻保存精子质量的细微差异将有助于确定精液在田间条件下使用前的潜在生育力。在本研究中，我们评估了具有不同田间生育力水平的杂交公牛（n = 22）中冷冻保存精子的酪氨酸磷酸化状态、膜完整性和顶体反应，并评估了它们与生育力的关系。根据不同的田间生育率，公牛被分为高于平均水平（n = 4）、平均（n = 14）和低于平均水平（n = 4）。进行性精子活力显着（P < 0. 05) 与平均或低于平均水平的可育公牛相比，高于平均水平的可育公牛更高，而三组之间的精子膜完整性和顶体反应状态没有差异。与高于平均水平的公牛相比，低于平均水平和平均可育公牛的活酪氨酸磷酸化精子的比例显着（P < 0.05）更高。精子中蛋白质酪氨酸磷酸化的免疫定位显示，在低于平均值的情况下，在顶体和顶体后区域（APA）以及顶体、顶体后和尾部（APAT）处显示酪氨酸磷酸化的精子比例显着（P < 0.05）更高比其他群体的能育公牛。APA 模式 (r = -0.605; P < 0.01) 和 APAT (r = 0.507; P < 0.05) 模式与公牛生育力呈显着负相关。