Comparison of chelated zinc and zinc sulfate as zinc sources for growth and immune response of shrimp (Litopenaeus vannamei)

Zinc methionine (ZnMet), zinc lysine (ZnLys), zinc glycine (ZnGly) and zinc sulfate (ZnSO4 · H2O) were evaluated as dietary zinc sources for Litopenaeus vannamei. Three Zn-amino acid complexes with a molar amino acid to Zn ratio of 2:1 were compared to Zn sulfate using a casein-based purified diet. Five groups with four replicates of shrimps (mean weight 0.72 ± 0.02 g) were given a basal diet either unsupplemented (control) or supplemented with 30 mg Zn kg− 1 sulfate (ZnSO4 · H2O) or the organic sources respectively, for 12 weeks. Results showed that the source of Zn affects shrimp growth, survival and immune parameters. Shrimp fed diets with organic zinc supplementation produced significantly higher growth, survival and immune parameters than ZnSO4 treatment. Shrimp supplemented with ZnMet had the highest weight gain and immune parameters. However, there were no significant differences in weight gain, survival, total hemocyte counts, phagocytotic activity, PO, AKP and SOD between the ZnLys and ZnGly groups. Results suggest that Zn from ZnMet was a better source than the other zinc forms.