The Effect of Using Different Zinc Sources on Performance, Blood Parameters, and Some Enzymes Related to the Immune System in Holstein Calves

This study aimed to evaluate the effects of different zinc sources on performance, blood parameters, and key immune system enzymes in calves. The experiment was conducted over a period of 70 days using 20 calves divided into four treatment groups. The treatments included: (1) a basal diet without zinc supplemen-tation, (2) a basal diet supplemented with 40 ppm zinc in the form of nano zinc oxide, (3) a basal diet sup-plemented with 40 ppm zinc in the form of zinc oxide, and (4) a basal diet supplemented with 40 ppm zinc in the form of zinc glycine. The results indicated that starter intake, total feed intake, daily weight gain, and final weight in calves fed diets containing different zinc forms showed significant improvement compared to the control group during the last month of the study (P<0.05). A significant difference was also observed between the control group and the groups receiving nano zinc oxide and zinc glycine during the second period of the experiment (P<0.05). Blood parameter analysis revealed that zinc supplementation had no significant effect. However, the zinc levels in the nano zinc oxide and zinc glycine groups were signifi-cantly higher compared to the control (P<0.05). Additionally, the inclusion of different zinc forms markedly influenced total antioxidant activity and superoxide dismutase concentration in calves (P<0.05). Overall, these findings suggest that dietary supplementation with various forms of zinc.