This study aimed to see the effect of oral supplementation of specific trace minerals mixture on the growth, immunity, and reproductive development of indigenous growing bull calves. Eighteen Sahiwal bull calves, with an average age of 6 months were chosen and divided into three groups. Group 1 was fed with a basal diet, Group 2 was provided with an additional specific trace mineral supplement to achieve a diet containing 70 ppm of Zn, 17.50 ppm of Cu, 65 ppm of Mn, and 1.75 ppm of Cr. Group 3 received a 25% extra supplement to achieve a diet containing 87.50 ppm of Zn, 21.87 ppm of Cu, 81.25 ppm of Mn, and 2.18 ppm of Cr. The experiment was carried out for a total of 180 days. According to the findings, there was no significant impact of specific trace minerals supplementation on the animals' body weight, morphometric parameters, dry matter intake, average daily gain, nutritional value, digestibility and nitrogen retention. However, higher levels of Zn, Cu, and Mn led to increased (p < 0.05) total retention, while Cr retention remained the same. Serum mineral concentrations of Zn, Cu, and Mn increased significantly (p < 0.05) in G2 and G3 compared to the G1 group while Ca, P, and Cr had no significant change. Blood plasma glucose, albumin, globulin, and total protein showed no significant differences. Plasma alkaline phosphatase activity improved significantly (p < 0.05) in G2 and G3 but alanine transaminase, aspartate aminotransferase, hemoglobin, hematocrit, and IGF-1 remained unchanged. Superoxide dismutase activity, ferric-reducing antioxidant power, and total immunoglobulin concentration increased significantly (p < 0.05) in G2 and G3 groups, however, catalase activity and IgG count did not change among the groups. Mineral-supplemented groups (G2 and G3) showed a significant change (p < 0.05) in testosterone production during the 120th and the 180th day of the trial. Scrotal circumference and temperature gradient of the scrotal surface did not show any significant change. Supplementing growing bull calves with specific trace minerals above the basal level (70, 17.50, 65 and 1.75 ppm of Zn, Cu, Mn and Cr) has no direct beneficial effect on the growth parameters but can have positive effects on their antioxidant status, immunity and reproductive development as the related blood parameters were positively affected.
Keywords: Bull calves; Chromium; Copper; Growth; Immunity; Manganese; Testosterone; Zinc.
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