Comparative evaluation of zinc hydroxychloride and zinc sulphate on growth performance, antioxidant status, immune function, and zinc bioavailability in growing crossbred calves.

Zinc (Zn) is an essential trace mineral involved in antioxidant defense, immune regulation, and metabolic processes in livestock. Hydroxy trace minerals such as zinc hydroxychloride (ZnOHCl) have gained attention due to their greater ruminal stability and potentially higher bioavailability compared with zinc sulphate (ZnSO4). This study evaluated the comparative effects of ZnOHCl and ZnSO4 supplementation on growth performance, hemato-biochemical parameters, antioxidant status, immune response, and Zn bioavailability in growing crossbred calves. Twenty-four male calves were randomly allocated to four dietary treatments for 120 days: a basal diet without Zn supplementation, 80 mg Zn/kg DM as ZnSO4, 40 mg Zn/kg DM as ZnOHCl, or 80 mg Zn/kg DM as ZnOHCl. Zinc supplementation, whether as ZnSO4 or ZnOHCl, did not significantly affect the growth performance of calves. However, it significantly enhanced antioxidant enzyme activities, total antioxidant capacity, immunoglobulin concentrations, and both cell-mediated and humoral immune responses, while reducing lipid peroxidation (P < 0.05), with no significant differences were observed among the Zn-supplemented groups. Hemato-biochemical parameters were unaffected by Zn supplementation, except for increased plasma globulin concentration and alkaline phosphatase (ALP) activity, with no significant differences among Zn-supplemented groups. Zinc retention, along with plasma and erythrocyte Zn concentrations, increased significantly with Zn supplementation, with the highest retention observed in calves receiving 80 mg Zn/kg DM as ZnOHCl. Supplementation did not influence the retention or plasma concentrations of other minerals. Overall, Zn supplementation, irrespective of source or level, improved antioxidant status, immune function, and Zn retention in growing crossbred calves.