The effect of the dietary inclusion levels and sources of zinc on the performance, metabolism, redox and immune status of turkeys

The aim of this experiment was to determine whether the inclusion levels of supplemental Zn in turkey diets could be reduced without compromising important metabolic functions, the immune status and growth parameters of birds, and whether the above goal can be achieved with the use of zinc (Zn) nanoparticles. The experiment was performed on 648 one-day-old Hybrid Converter turkey hens divided into 6 groups with 6 replicates (18 birds per pen), in a two-factorial design with three dietary supplemental levels of Zn (100, 50 and 10 mg/kg) and two dietary sources of Zn- conventional zinc oxide (ZnO) and Zn nanoparticles (NP-ZnO). The applied inclusion levels and sources of Zn had no effect on the growth performance of turkeys, including liveability. The replacement of ZnO with NP-ZnO in turkey diets led to an increase in the levels of albumin (ALB), triacylglycerols (TG) and alkaline phosphatase (ALP) activity in the blood serum as well as minor changes in redox indicators including a decrease in plasma malondialdehyde (MDA) levels, catalase (CAT) activity in the liver, and total glutathione (GSH + GSSG) and MDA levels in the bursa of Fabricius. The addition of 50 mg and 100 mg of Zn exerted similar effects on blood biochemical parameters and antioxidant status indicators in the liver. Only in the bursa of Fabricius, the moderate dietary inclusion level of Zn contributed to a decrease in GSH + GSSG levels. The results of this study indicate that the recommended level of ZnO supplementation in turkey diets can be reduced to 50 mg/kg. A decrease in the dose of supplemental Zn from 100 to 10 mg/kg did not compromise the growth performance of turkeys, but it had a negative effect on lipid metabolism by increasing plasma TG concentrations. The replacement of ZnO with NP-ZnO had no beneficial influence on performance, the immune and antioxidant status of turkeys.