Effects of feed supplementation with various zinc sources on mineral concentration and selected antioxidant indices in tissues and plasma of broiler chickens

The aim of this study was to compare the effects of organic dietary zinc (Zn) sources and zinc sulphate on mineral deposition, activity of total superoxide dismutase (SOD) and copper/zinc SOD in tissues of broiler chickens. The performance indicators and lipid peroxidation by measuring the contents of thiobarbituric acid reactive substances (TBARS) in tissues and plasma were also evaluated. Broilers were assigned to 4 treatment groups, each replicated x 6, with 9 birds per replicate. The control group was fed conventional basal diet (BD); the three other groups received identical BD supplemented with 120 mg Zn/kg in the form of zinc sulphate, zinc chelate of glycine hydrate (Zn-Gly), and zinc proteinate (Zn-Pro), respectively. After 5 weeks of dietary treatment, feed supplementation with Zn sulphate resulted in significantly higher average daily weight gain and final body weight, as well as improved feed conversion ratio compared to the Zn-Gly group. Intake of Zn-Pro significantly increased SOD activity (P < 0.05) in erythrocytes and lipid peroxidation (P < 0.01) in plasma. Activities of total SOD and Cu/Zn SOD in liver and kidney were not affected by Zn supplementation. Addition of Zn supplements to broiler diets did not influence concentrations of zinc, manganese and copper in plasma, liver, kidney or breast muscle, with the exception of Zn deposition in the liver being significantly higher (P < 0.05) in the Zn-Pro supplemented group. Results of our study show that organic zinc sources have effects comparable to inorganic zinc sulphate in broilers fed diets containing a higher Zn content.