Dietary zinc requirements of grass shrimp, Penaeus monodon, and effects on immune responses

Abstract

An 8-week feeding trial was conducted to determine the dietary zinc (Zn) requirement and its effect on the non-specific immune responses of juvenile grass shrimp, Penaeus monodon. Zinc was supplemented at 0, 10, 20, 30, 40, 50, 80 and 120 mg/kg diet in the basal diet providing of 7, 17.5, 28, 35, 48, 57, 87 and 127 mg Zn/kg diet, respectively. Each diet was fed to triplicate groups of shrimp with initial body weight of 0.44 ± 0.01 g. Shrimp fed diets supplemented with ≥ 35 mg Zn/kg had significantly ( P < 0.05) greater weight gain than those fed diets with ≤ 17.5 mg Zn/kg. Hepatopancreatic and whole body Zn concentration in shrimp generally increased as dietary Zn supplementation increased. Both intracellular superoxide anion (O 2 −) production ratios and total haemocyte count (THC) were highest in shrimp fed diets with 35 and 48 mg Zn/kg. Analysis by broken-line regression of weight gain and by linear regression of the whole body Zn retention of shrimp indicated that the adequate dietary Zn concentration in growing P. monodon is 32–34 mg Zn/kg diet. The immune indicators suggest that an adequate dietary Zn concentration for non-specific immune responses in P. monodon is about 35–48 mg Zn/kg diet.