Evaluation of oxidative stress, compositional and biochemical changes in milk and serum of cows with subclinical mastitis

Subclinical mastitis (SCM) has a detrimental impact on cow’s milk characteristics. The study was to investigate the consequences of SCM on milk composition and blood biochemistry, oxidative stress biomarkers, and the correlation between different milk and serum parameters in SCM-affected cows. The multiparous Holstein cows were grouped as 16 subclinical infected and nine healthy according to milk somatic cell count and California Mastitis Test scores. The blood and milk samples were gathered from each animal and evaluated for compositional, biochemical, and oxidative stress marker alterations. SCM-affected milk samples showed a significant (P < 0.05) decrease in fat, protein, lactose, total solids, solids-non-fat percentages, and total antioxidant capacity (TAC) and a significant (P < 0.05) increase in ash %, catalase, and malondialdehyde (MDA). Milk somatic cell count showed a positive correlation with MDA and catalase. Milk fat showed a positive correlation with lactose, total protein, and albumin. A significant increase in catalase and total protein associated with a significant decrease in Ca level was recorded in SCM blood samples. The results indicate that a significant correlation between different parameters in blood and milk can be useful as a proper clinical indicator for the early detection of SCM in cows.