School of Agriculture and Food Science, University College Dublin, Belfield, Dublin 4, Ireland.
ALLICE, Innovation and Development, 149 rue de Bercy, 75012, Paris, France.
J Dairy Sci. 2022 Nov;105(12):10033-10046. doi: 10.3168/jds.2022-22273. Epub 2022 Oct 26.
Despite passing stringent quality control, bulls used in artificial insemination can vary significantly in their fertility, emphasizing the need for reliable markers of sperm quality. This study aimed to identify sperm proteins acting as biomarkers of fertility in 2 different populations of dairy bulls classified based on their field fertility. Semen was collected and cryopreserved from: 54 Holstein bulls located in Ireland, classified according to fertility indexes as low fertility (LF, n = 23), medium fertility (n = 14), or high fertility (HF, n = 17); and 18 Holstein bulls located in Denmark, classified as LF (n = 8) or HF (n = 10). The proteome was measured through liquid chromatography-mass spectrometry and data were analyzed with the R software. Differentially abundant proteins between HF and LF bulls and biomarker proteins were determined through a modified t-test and random forest, respectively, selecting 301 differentially abundant proteins and 34 biomarker proteins. The predictive ability of the 34 biomarkers was evaluated employing support vector machine as the classifier, using their abundance levels in the Irish bulls to train the model and in the Danish bulls for validation. The prediction accuracy was 94.4%, with only one HF bull misclassified, corresponding to the lowest fertility index bull in the HF group. The biomarkers more abundant in sperm of HF bulls enriched axoneme assembly and sperm motility (false discovery rate <0.05), according to functional analysis. In conclusion, a robust model coupled with the application of appropriate bioinformatic tools allowed the identification of functionally relevant sperm proteins predictive of the fertility of Holstein bulls used in artificial insemination.
尽管经过严格的质量控制，但用于人工授精的公牛在生育能力上可能存在显著差异，这强调了需要可靠的精子质量标志物。本研究旨在鉴定在基于其田间生育力分类的两个不同奶牛公牛群体中作为生育力标志物的精子蛋白。从以下两个群体收集和冷冻保存精液：54 头爱尔兰荷斯坦公牛，根据生育力指数分为低生育力（LF，n = 23）、中生育力（n = 14）或高生育力（HF，n = 17）；和 18 头丹麦荷斯坦公牛，分为低生育力（LF，n = 8）或高生育力（HF，n = 10）。通过液相色谱-质谱法测量蛋白质组，使用 R 软件分析数据。通过改良的 t 检验和随机森林分别确定 HF 和 LF 公牛之间差异丰度的蛋白质和生物标志物蛋白，选择 301 个差异丰度蛋白和 34 个生物标志物蛋白。使用支持向量机作为分类器评估 34 个生物标志物的预测能力，使用爱尔兰公牛中的丰度水平训练模型，使用丹麦公牛进行验证。预测准确率为 94.4%，仅 1 头 HF 公牛被错误分类，对应 HF 组中生育力指数最低的公牛。根据功能分析，HF 公牛精子中更丰富的生物标志物富集轴丝组装和精子活力（错误发现率<0.05）。总之，强大的模型与适当的生物信息学工具的应用相结合，允许鉴定预测用于人工授精的荷斯坦公牛生育力的功能相关精子蛋白。
