Abstract

To study the immunological activities of neutrophils, blood samples were collected from 6 high yielding (HY) and 6 low yielding (LY) Karan Fries (KF) cows on -15,-7, -5, -3, -2, -1 days prepartum, at calving and on 1, 2, 3, 5, 7 and 15 days postpartum. Plasma cortisol levels, phagocytic activity (PA), enzyme (Elastase, Collagenase and Cathepsin G) levels and expression of TLR-2, TLR-4 and IL-8 were also studied. Both HY KF and LY KF cows were found to have increased blood Total leukocyte counts (TLC) and neutrophil percent at calving, but HY KF cows had significantly (P<0.05) higher levels than LY KF cows. The number of band neutrophils were also significantly (P<0.05) higher in HY cows. Significant (P<0.05) immunosuppression in relation to PA was found for HY as compared to LY KF cows throughout the peripartum period, with the lowest immunosuppression at calving in both groups of cows. Cortisol levels were significantly (P<0.01) higher during calving and negatively correlated with neutrophilic functions. The difference between the two groups also remained significant (P<0.05) as higher level of cortisol were found in HY KF cows. Elastase, collagenase and cathepsin were significantly (P<0.05) decreased during parturition. Elastase was reduced approximately 2.5 times on the day of calving in LY KF cows, but no such major reduction was observed for HY KF cows. Collagenase and cathepsin levels were significantly (P<0.05) higher in LY cows. Expression of the TLR-2 gene was significantly (P<0.05) lower in HY cows during the whole peripartum period than in LY cows. Expression of the TLR-4 gene was significantly (P<0.05) lower on days 15 pre- and post-calving in HY cows. IL-8 differed significantly (P<0.05) only during the prepartum days. Lower neutrophilic function in cross bred cows with high production potential, provides lower disease resistance and makes the cows more susceptible to peripartum infection.