Unveiling the metabolic impact of recombinant growth hormone in dairy cows: an integrated metabolomics analysis of milk and urine

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Recombinant bovine growth hormone (rbGH or rbST) is a synthetic analogue of a natural hormone used to enhance growth and milk production in dairy cattle. While its use is authorised in some countries, it is strictly prohibited in Europe due to food safety issues and ethical concerns. Consequently, robust analytical strategies, including immunoassays and LC-MS/MS, are employed for its detection. In this study, we applied untargeted metabolomics and lipidomics profiling using liquid chromatography-high‑resolution mass spectrometry (LC‑HRMS) to investigate the systemic effects of rbGH administration. Urine and milk samples were collected from nine dairy cows over a time course covering multiple stages of rbGH treatment. Data pre-processing and feature extraction were performed using the Galaxy Workflow4metabolomics platform, and discriminant metabolites were selected through multivariate models based on variable importance in projection (VIP). Results showed that urine metabolomics revealed rapid perturbations in polar metabolites shortly after the first rbGH administration, while milk lipidomics highlighted more progressive and dynamic shifts in lipid composition. These findings demonstrate an early disruption of polar metabolism followed by slower reprogramming of lipid metabolism. This integrative LC‑HRMS approach provides new insights into the molecular consequences of rbGH exposure, contributing both to the development of refined biomarker strategies for monitoring unauthorised hormone use in livestock and to a better understanding of the intrinsic hazards associated with rbGH. By elucidating the biological pathways and metabolic disruptions involved, the study supports more informed chemical risk assessments and strengthens the scientific basis for evaluating potential adverse effects on animal health and food safety.