Nuclear Magnetic Resonance-based Metabolomics of Blood Plasma from Dairy Calves Infected with the Main Causal Agents of Bovine Respiratory Disease (BRD)

Each year, Bovine Respiratory Disease (BRD) results in significant economic loss in the cattle sector, and novel metabolic profiling and early diagnosis techniques represent a promising tool for developing effective measures for disease management. Here, proton - Nuclear Magnetic Resonance ( 1 H - NMR) spectra were used to characterize metabolites from blood plasma collected from dairy calves intentionally infected with the main BRD causal agents, bovine respiratory syncytial virus (BRSV) and Mannheimia haemolytica (MH), to generate a well-defined metabolomic profile under controlled conditions. In response to infection, 42 metabolites (BRSV = 27, MH = 24) changed in concentration compared to the Baseline (non-infected) state. Fuel substrates and products exhibited a particularly strong effect, reflecting imbalances that occur during the immune response. Glucose levels decreased only during bacterial infection, suggesting that the clinical signs of bacterial BRD are more energetically taxing than those of viral BRD. Furthermore, 1 H - NMR spectra from Baseline and Infected samples were discriminated with an accuracy, sensitivity, and specificity ≥ 95% using chemometrics to model the changes associated with disease, suggesting that metabolic profiles can be used for further development and validation of diagnostic tools.