Vol. 7, Issue 12, Part A (2025)

The present study investigated the metabolic alterations associated with intramammary infections (IMI) caused by Staphylococcus aureus and Escherichia coli in early-lactating Sahiwal cows, with emphasis on β-hydroxybutyrate (BHBA) and non-esterified fatty acids (NEFA) in plasma and milk. A total of 24 mastitis-affected cows (12 clinical, 12 subclinical) were selected after screening 73 animals using mCMT and clinical examination. Results showed that cows infected with E. coli exhibited significantly higher (P<0.05) plasma and milk BHBA and NEFA concentrations compared to S. aureus. Seasonal variations were also significant (P<0.05), with both plasma and milk BHBA and NEFA reaching their highest levels during summer, indicating pronounced metabolic stress under heat load. Clinical mastitis cows demonstrated markedly elevated (P<0.05) BHBA and NEFA values in both plasma and milk across all seasons compared to subclinical cases, revealing greater lipid mobilization and impaired energy balance in severe infections. The study overall underscores the joint impact of mastitogen type, the severity of the disease, and seasonal heat stress on metabolic dysregulation in Sahiwal cows. It highlights the importance of BHBA and NEFA as potential biomarkers for evaluating the severity of mastitis and metabolic stress.