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

## TL;DR

Injecting trace minerals and vitamins in young Nellore calves improves their immune health and antioxidant levels but does not boost growth.

## Contribution

Injectable trace minerals and vitamins enhance immune and antioxidant status in calves without affecting growth performance.

## Key findings

- Injectable supplementation increased copper and selenium levels in blood and liver.
- The treatment improved antioxidant activity and hematological parameters.
- Immune response shifted toward a less inflammatory state.

## Abstract

This research showed that giving trace mineral and vitamin injections to nursing Nellore calves significantly benefits their health. The treatment increased the levels of key nutrients, such as the minerals copper and selenium, in the blood and liver, which helped the animals’ bodies defend themselves more effectively. In practice, these nutrients helped balance the body’s defenses, directing the immune response towards a less inflammatory state. On the other hand, the study found that these health improvements did not lead to extra weight gain or faster growth. This suggests that this type of supplement acts more as a protector of the immune system than as a tool to speed up the physical growth of the animals.

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; n = 19) or injectable supplementation of trace minerals (copper, manganese, zinc, and selenium) and vitamins (A and E) (ITMV; n = 19), administered on days 75 and 150 of the calves’ age. The injectable supplementation did not affect (p > 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 (p ≤ 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 (p ≤ 0.05) glutathione peroxidase activity, higher red blood cell count, hemoglobin, and hematocrit levels, and a lower neutrophil/lymphocyte ratio (p = 0.04). In the metabolic profile, only a day effect was observed (p ≤ 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.