Active immune system and dry matter intake during the transition period are associated with postpartum fertility in lactating Zebu cows

Abstract

The aim of the present study was to assess if the metabolic adaptation and immune status during transition period influence the postpartum reproductive performance in dairy cattle. We assessed the levels of innate immune molecules (Haptoglobin: Hp, Serum Amyloid A: SAA, IL-6, TNF-α, IL-1β, and IL-8) and energy balance indicators [NEFA and Dry Matter Intake (DMI)] in transition Zebu (Deoni breed) cows that became pregnant within breeding period (n = 7) and remained non-pregnant (n = 10) even after the breeding period (i.e. from 45 to 180 days postpartum). Blood samples were collected at weekly intervals during transition period (−21 d before to 21 d after calving) and plasma variables were estimated using commercially available bovine specific ELISA kits. Plasma Hp concentration was significantly (P < 0.01) higher in cows that became pregnant during breeding period as compared to those that remained non-pregnant. While plasma TNF-α concentrations differed significantly (P = 0.05) between groups, such difference was not observed with SAA concentrations. Group x time interaction had a significant effect on plasma IL-6 (P < 0.01), IL-1β (P = 0.05), IL-8 (P = 0.05) concentrations and DMI (P = 0.001). Plasma NEFA concentrations differed significantly (P = 0.03) between groups, although all the experimental cows had NEFA concentrations within the physiological limits. Days in milk had a significant effect on milk yield (P = 0.001) and fat percentage (P = 0.03). It is concluded that active functioning of immune system, stable dry matter intake, and limited fat mobilization during transition period enabled the cows to conceive early during postpartum period.