The purpose of this study was to analyse the effects of season, age, gonad and accessory sex glands on semen characteristics of jackass and to construct multivariate regression models to predict semen quality. In autumn, spring and summer, semen characteristics of 30 sexually mature donkeys (1,014 ejaculations) were analysed to investigate the effect of seasons on semen quality, and gonad and accessory sex gland parameters of 12 jackasses were measured immediately after ejaculation by ultrasonography to investigate the effect of seasons on reproductive organ size. Semen (598 ejaculates), gonad and accessory sex gland parameters of 40 jackasses aged between 3 and 7 years were analysed in autumn to investigate the effects of age and reproductive organ size on semen quality and to construct multivariate models. To verify the accuracy of the models, semen (476 ejaculates), gonad and accessory sex gland parameters of 20 jackasses were measured from March to June. Results revealed that semen, gonad and accessory sex gland parameters were not affected by season and age. Progressive motility (PM) was positively correlated with long axis of the spermatic cord (LASC) and negatively correlated with percentages of sperm abnormality (PSA). Total sperm count (TSC) was positively correlated with testis circumferences (TC) and cross‐sectional area of cauda epididymis (CSACE). TC, CSACE, LASC and PSA were included into multivariate models to predict PM, TSC and functional sperm count (FSC) in 20 jackasses (PM = 72.332 + 0.428 LASC − 0.441 PSA; TSC = −169.929 + 8.728 TC + 0.253 CSACE; FSC = −206.645 + 8.788 TC + 0.258 CSACE). The predicted and observed values corresponded well. In conclusion, the tested models can be used for predicting semen quality of donkey.

中文翻译：

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估计jack精液产量和质量的多元模型

这项研究的目的是分析季节，年龄，性腺和副性腺对公驴精液特征的影响，并建立多元回归模型以预测精液质量。在秋季，春季和夏季，分析了30只性成熟的驴（1,014射精）的精液特征，以调查季节对精液质量的影响，并在超声检查后立即测量了12头公驴的性腺和性腺参数，以调查它们的精子质量。季节对生殖器官大小的影响。秋季分析了40头3至7岁的蜜糖的精液（598个精液），性腺和性腺参数，以调查年龄和生殖器官大小对精液质量的影响，并建立多元模型。为了验证模型的准确性，从3月到6月，测量了20个公驴的精液（476精液），性腺和性腺参数。结果显示，精液，性腺和副性腺参数不受季节和年龄的影响。进行性运动（PM）与精索长轴（LASC）正相关，与精子异常百分比（PSA）负相关。总精子数量（TSC）与睾丸周长（TC）和附睾马尾横断面积（CSACE）正相关。TC，CSACE，LASC和PSA包括在多变量模型中，以预测20种公驴的PM，TSC和功能性精子计数（PM = 72.332 + 0.428 LASC − 0.441 PSA; TSC = −169.929 + 8.728 TC + 0.253 CSACE; FSC = −206.645 + 8.788 TC + 0.258 CSACE）。预测值和观察值非常吻合。综上所述，