In this study, we evaluated the effects of supplementation of the maternal diet with organic trace minerals including Zn (zinc), Mn (manganese), Cu (copper), and Co (cobalt) on the health and immune status of beef calves. We examined 19 pregnant cows, which were divided into a group of 9 cows fed a basal diet (control) and 10 cows fed a diet with organic trace minerals (treated). Cows were fed for a period of 45 days before the predicted calving date until 45 days after calving. The number of treatments needed for respiratory and digestive diseases within 14 days of birth was significantly lower in the treated group (p < 0.05) than the control group. In addition, the concentration of serum zinc in the treated group on day 1 was significantly higher (p < 0.05) than that in the control group. The numbers of CD4+ and CD8+ cells in the treated group on days 30 and 60 were significantly increased (p < 0.01) compared with those in the control group, as was the number of γδ T cells on days 1 and 30 (p < 0.05). The number of IgM+ cells in the treated group on days 30 and 60 was significantly increased (p < 0.01) compared with that in the control group, as was the number of MHC class II+ cells on day 60 (p < 0.01). The number of NK cells in the treated group on day 60 was also significantly increased (p < 0.05) compared with that in the control group. The expression levels of mRNAs encoding interlukin-2 (IL-2), interlukin-4 (IL-4), interlukin-12 (IL-12), and interferon-γ (IFN-γ) in the treated group were significantly higher than those in the control group (p < 0.05) on days 1 and 60. The results indicate that maternal supplementation with trace minerals is a promising approach for producing highly disease-resistant calves and enhancing calf immunity.
Keywords: Japanese black calf; immunity; late gestation; respiratory disease; trace minerals.