The main aim of the current investigation was to evaluate the relationships between metabolic parameters, acute-phase proteins, and the outcome of treatment of Staphylococcus aureus subclinical mastitis in dairy cows. Serum metabolic parameters and milk haptoglobin were measured in two groups: S. aureus subclinical mastitis cows with successful treatment (n = 26) and S. aureus subclinical mastitis cows with unsuccessful treatment (n = 26). Significantly higher serum aspartate aminotransferase (AST), alkaline phosphatase (ALP), and LDL cholesterol concentrations were seen in subclinical mastitis cows with unsuccessful treatment compared to subclinical mastitis cows with successful treatment (p < 0.05). On the other hand, subclinical mastitis cows with successful treatment demonstrated higher serum iron and copper concentrations than the other group (p < 0.05). Comparison of measured variables before treatment revealed that cows suffering from subclinical mastitis with higher values of serum LDL cholesterol, ALP, and AST did not respond to antibiotic treatment and subclinical mastitis was persisted in the second examination, whereas subclinical mastitis cows with successful treatment demonstrated higher serum copper and iron concentrations (p < 0.05). The findings of the current investigation suggested that there was a relationship between the treatment outcome of S. aureus subclinical mastitis and trace element concentrations and liver health status. Furthermore, the present study provided cutoff values for serum LDL cholesterol, AST, ALP, iron, and copper, which would help predict the treatment outcome in cows with S. aureus subclinical mastitis

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