Selective, reliable blood and milk bio-markers for diagnosing clinical and subclinical bovine mastitis.

Mastitis is positioned as the most vital ailment in dairy cows in light of conventional cost examinations. The aim of the present study was to evaluate the diagnostic value of different acute phase proteins (APPs), pro-inflammatory cytokines, and oxidative stress biomarkers in healthy cows and in those with clinical or subclinical mastitis and to localize APP gene expression in the milk of mastitic cows. Therefore, 20 subclinical mastitic cows with positive California Mastitis Test (CMT) results and no clinical signs of mastitis, 15 clinically mastitic cows, and 15 healthy cows with negative CMT results and somatic cell count (SCC) of <600,000 cells/mL were selected. Milk and blood samples were collected. The present findings indicate that the biochemical parameters examined were significantly (p < 0.05) increased in cows with both types of mastitis, except for total protein, albumin, and GSH levels and the TAC, which were significantly (p < 0.05) decreased, compared with values in the controls. Surprisingly, SAA and Hp gene expression were up-regulated in milk from cows with both forms of mastitis, while Fb expression was absent. The present study demonstrates that APPs, pro-inflammatory cytokines, and indicators of oxidative stress may serve as biomarkers of clinical and subclinical mastitis. Interestingly, the expression of SAA and Hp indicates the local de novo synthesis of these APPs within the mammary glands. Furthermore, the presence of SAA and Hp transcripts in milk cells derived from pathogen-free mammary glands proved their constitutive expression. However, future studies with more extensive baseline sampling are still needed to establish and validate the reference values for APPs, cytokines, and oxidative stress markers in cows.