The effect of injectable trace minerals (selenium, copper, zinc, and manganese) on peripheral blood leukocyte activity and serum superoxide dismutase activity of lactating Holstein cows

The objective of this study was to evaluate the effect of subcutaneous supplementation of 300 mg of zinc, 50 mg of manganese, 25 mg of selenium, and 75 mg of copper on peripheral blood leukocyte activity and serum β-hydroxybutyrate (BHBA) concentrations at 10 ± 2 days in milk (DIM), and on serum superoxide dismutase (SOD) activity during the transition period and subsequent lactation of multiparous Holstein cows. A total of 250 multiparous cows were randomly allocated into one of two treatments groups, namely, trace mineral supplemented (TMS) or control. Cows in the TMS group were injected at 230 and 260 days of gestation, and 35 days postpartum. Serum SOD activity was measured at enrollment, and 10, 60 and 100 DIM. Serum BHBA concentration and leukocyte function were assessed at 10 DIM. Overall serum SOD activity for TMS and control was 16.01 and 12.71 U/mL, respectively. The interaction between treatment and time of serum collection was significant. Additionally, overall serum SOD activity was 12.85 and 14.78 U/mL for cows diagnosed with mastitis and unaffected cows, respectively. Treatment did not affect leukocyte function. For parity >2, TMS cows had lower serum BHBA concentrations than control cows; BHBA concentrations were 0.41 and 0.27 mmol/L for control and TMS cows, respectively. In conclusion, cows diagnosed with mastitis had decreased serum SOD activity, and trace mineral supplementation increased serum SOD activity although leukocyte function was not affected by supplementation.