Clinical mastitis (CM), the most prevalent and costly disease in dairy cows, is diagnosed most commonly shortly after calving. Current indicators do not satisfactorily predict CM. This study aimed to develop a robust and comprehensive mass spectrometry-based metabolomic and lipidomic workflow using untargeted ultra-performance liquid chromatography high-resolution mass spectrometry for predictive biomarker detection. Using a nested case-control design, we measured weekly during the prepartal transition period differences in serum metabolites, lipids, inflammation markers, and minerals between clinically healthy Holstein dairy cows diagnosed with mastitis postcalving (CMP; n = 8; CM diagnosis d 1 = 3 cows, d 2 = 2 cows, d 4 = 1 cow; d 25 = 1 cow, and d 43 = 1 cow that had subclinical mastitis since d 3) or not (control; n = 9). The largest fold differences between CMP and control cows during the prepartal transition period were observed for 3'-sialyllactose in serum. Seven metabolites (N-methylethanolamine phosphate, choline, phosphorylcholine, free carnitine, trimethyl lysine, tyrosine, and proline) and 3 metabolite groups (carnitines, AA metabolites, and water-soluble phospholipid metabolites) could correctly classify cows for their future CM status at both 21 and 14 d before calving. Biochemical analysis using lipid and metabolite-specific commercial diagnostic kits supported our mass spectrometry-based omics results and additionally showed elevated inflammatory markers (serum amyloid A and visfatin) in CMP cows. In conclusion, metabolic phenotypes (i.e., metabotype) with elevated protein and lipid metabolism and inflammation may precede CM in prepartal transition dairy cows. The discovered serum metabolites and lipids may assist in predictive diagnostics, prevention strategies, and early treatment intervention against CM, and thereby improve cow health and welfare.

中文翻译：

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在产前过渡期奶牛中，蛋白质和脂质分解代谢和炎症升高的代谢型先于临床乳腺炎。

临床乳腺炎（CM）是奶牛中最普遍且成本最高的疾病，在产犊后不久就被最常见地诊断出来。当前的指标不能令人满意地预测CM。这项研究的目的是使用无目标的超高效液相色谱高分辨率质谱技术来预测生​​物标志物，从而开发出一种强大而全面的基于质谱的代谢组学和脂质组学工作流程。使用巢式病例对照设计，我们在产前过渡期每周测量诊断为产后乳腺炎的临床健康荷斯坦奶牛之间的血清代谢物，脂质，炎症标志物和矿物质的差异（CMP； n = 8； CM诊断d 1 = 3头母牛，d 2 ＝ 2头母牛，d 4 ＝ 1头母牛； d 25 ＝ 1头母牛，d 43 ＝ 1头自d 3起就患有亚临床乳腺炎的母牛（对照； n = 9）。对于血清中的3'-唾液乳糖，在产前过渡期中观察到了CMP母牛与对照母牛之间最大的倍数差异。七个代谢物（N-甲基乙醇胺磷酸盐，胆碱，磷酸胆碱，游离肉碱，三甲基赖氨酸，酪氨酸和脯氨酸）和3个代谢物组（肉碱，AA代谢物和水溶性磷脂代谢物）可以正确地将母牛分类为将来的CM状态产犊前21和14 d。使用脂质和代谢物特异性的商业诊断试剂盒进行的生化分析支持了我们基于质谱的组学结果，并且还显示了CMP奶牛的炎症标志物（血清淀粉样蛋白A和visfatin）升高。总之，代谢表型（即 蛋白和脂质代谢和炎症升高的代谢型可能会在产前过渡期奶牛的CM发病之前发生。发现的血清代谢物和脂质可能有助于针对CM的预测诊断，预防策略和早期治疗干预，从而改善奶牛的健康和福利。