RESUMEN
We aimed to determine whether the use of injectable vitamins and minerals improves growth performance and immune and antioxidant responses in dairy calves during pre- and post-weaning period in summer. Twenty dairy calves (45 days of age) were randomized to two groups (10 each): control group (CON) and treated group [TREAT; injection providing 0.20, 0.80, 0.20, 0.10, 35 and 1â¯mg/kg of copper, zinc, manganese selenium, and vitamins A and E, during two periods (15 days pre- and 15 days post-weaning)]. The animals were weighed and blood samples were collected on days 1, 15, 30 and 45 of the study. Levels of serum copper, selenium, zinc, and manganese were measured on day 1; and the results showed that calves were not deficient in these minerals. The TREAT group had greater BW gain during the final third of the experiment. There was an increase in total leukocyte numbers as a result of elevation in neutrophil counts (day 45) and monocytes (days 30 and 45) in the TREAT group. This group also had lower reactive oxygen species (ROS) content (days 15, 30 and 45) and lipid peroxidation (LPO; days 15 and 45). Furthermore, the TREAT group had greater antioxidant capacity against peroxyl radicals (ACAP; days 15 and 30), activities of the enzymes glutathione peroxidase (GPx; days 15, 30 and 45) and superoxide dismutase (SOD; day 15), concentrations of total serum proteins (day 30), serum globulin (days 15 and 30), ceruloplasmin (day 15), tumor necrosis factor-alpha (TNF-α), interleukin-1, (IL-1; days 30 and 45) and interferon gamma (IFNγ; day 45), compared to CON group. High respiratory rates during hot times of the day in all study calves was suggestive of heat stress. Taken together, the data suggest that mineral and vitamins injections increased the growth performance and boosted the antioxidant and immunological systems of dairy calves during the diet transition period in summer.