Although season has been shown to affect bull sperm quality and fertility in some studies, the effect of season on seminal plasma proteins has not been examined. In the present study, seminal plasma proteins were analysed by Fast Protein Liquid Chromatography (FPLC), to separate the phosphorylcholine-binding proteins and heparin-binding proteins from the other proteins. Semen samples were collected from bulls in three seasons: winter, summer and the rainy season. Sperm quality was analysed by flow cytometry and computer assisted sperm analysis, and further aliquots of semen were used to prepare the seminal plasma for FPLC. Meteorological data were available from a location close to the bull station. There were slight differences in sperm kinematics between seasons, but other parameters of sperm quality were not different. Minor differences in the phosphorylcholine-binding proteins were detected according to season, being lower in summer than in winter or in the rainy season, although there were no changes in the heparin-binding proteins. Temperature, humidity and rainfall differed between winter and the rainy season, but no differences were observed between summer and the rainy season except in the temperature humidity index (THI). However, the THI was above the threshold indicative of heat stress in all seasons, which could explain why few seasonal differences in protein composition were detected in this study. Alternatively, the bulls could have been well-adapted to heat stress. In conclusion, there were only slight differences in bull sperm quality and seminal plasma proteins between seasons during this study.

中文翻译：

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季节对泰国牛精浆蛋白的影响

尽管在一些研究中已经证明季节会影响公牛精子的质量和生育能力，但尚未研究季节对精浆蛋白的影响。在本研究中，通过快速蛋白质液相色谱 (FPLC) 分析精浆蛋白，将磷酸胆碱结合蛋白和肝素结合蛋白与其他蛋白质分离。从三个季节收集公牛的精液样本：冬季、夏季和雨季。通过流式细胞术和计算机辅助精子分析来分析精子质量，并使用进一步的精液等分试样制备用于 FPLC 的精浆。气象数据可从靠近公牛站的位置获得。季节间精子运动学略有差异，但精子质量的其他参数没有差异。尽管肝素结合蛋白没有变化，但根据季节检测到磷酸胆碱结合蛋白的微小差异，夏季低于冬季或雨季。冬季和雨季之间的温度、湿度和降雨量存在差异，但夏季和雨季之间除温湿度指数（THI）外没有差异。然而，THI 在所有季节都高于指示热应激的阈值，这可以解释为什么在本研究中几乎没有检测到蛋白质组成的季节性差异。或者，多头可能已经很好地适应了热应激。总之，在本研究期间，不同季节的公牛精子质量和精浆蛋白仅存在细微差异。