Effect of Trace Mineral and Vitamin Injections on Performance, Immunity, Mineral Status, and Antioxidant Responses of Nellore Calves During the Pre-Weaning Phase

The objective of this research was to investigate how injectable trace minerals and vitamins influence the mineral and vitamin status, hematological parameters, antioxidant capacity, metabolic profile, and performance of Nellore calves during the pre-weaning phase. A total of 38 grazing Nellore male calves with access to creep feeding were randomly assigned to two treatments: injectable supplementation of saline solution (saline; <i>n</i> = 19) or injectable supplementation of trace minerals (copper, manganese, zinc, and selenium) and vitamins (A and E) (ITMV; <i>n</i> = 19), administered on days 75 and 150 of the calves' age. The injectable supplementation did not affect (<i>p</i> > 0.05) body weight, average daily gain, body measurements, or carcass measurements throughout the experimental period from 75 to 218 days (7 days before weaning) of age. However, ITMV-treated calves showed higher (<i>p</i> ≤ 0.05) liver concentrations of Cu and Se on day 195 than saline calves. Higher plasma concentrations of Cu (days 195 and 218) and Se (days 135, 195, and 218) were observed for ITMV calves compared to the saline group. Furthermore, the ITMV group showed greater (<i>p</i> ≤ 0.05) glutathione peroxidase activity, higher red blood cell count, hemoglobin, and hematocrit levels, and a lower neutrophil/lymphocyte ratio (<i>p</i> = 0.04). In the metabolic profile, only a day effect was observed (<i>p</i> ≤ 0.05). In conclusion, the injectable supplementation of trace minerals and vitamins in suckling Nellore calves improved copper and selenium status and optimized antioxidant capacity and hematological parameters, in addition to modulating the immune response towards a less inflammatory state, although it did not affect performance or the metabolic profile.