Effect of micronutrient supplementation on the immune function of crossbred dairy cows under semi-arid tropical environment.

This study assessed the effect of micronutrient supplementation around peripartum period on immune function, reproductive performance, milk yield and milk quality of crossbred cows. Thirty pregnant crossbred cows in their late gestation were selected and randomly divided into five groups for study. Six cows in each group were supplemented with vitamin E (VE) (2000 IU/cow/day), vitamin A (VA) (100,000 IU/cow/day), copper (Cu) (20 ppm/cow/day), zinc (Zn) (80 ppm/cow/day) individually from 45 days pre-calving to 45 days post-calving and one group without any supplementation served as control. Immune function was studied by in vitro phagocytic activity (PA) of blood neutrophils, lymphocyte proliferation response (LPR) and plasma interleukin-8 (IL-8) concentration. Supplementation of VA significantly (P < 0.05) increased the in vitro PA of blood neutrophils and decreased milk somatic cell counts (SCC). Zn supplementation significantly (P < 0.05) increased the T lymphocyte proliferation response, whereas B lymphocyte LPR was significantly (P < 0.05) increased with both VA and Zn supplementation as compared to the control cows. Plasma IL-8 concentration was significantly (P < 0.05) higher in all supplemented cows. Supplementation of VE, VA and Zn significantly (P < 0.05) reduces days open, whereas VA significantly (P < 0.05) reduced the service per conception. In this study, it is concluded that VE, VA and Zn supplementation around peripartum period can boost the immunity and improve the reproductive performance of crossbred cows in a semi-arid tropical environment.