Dietary zinc requirement of fingerling channel catfish

Two experiments were conducted in order to establish the essentiality of zinc for fingerling channel catfish (Ictalurus punctatus) and to determine their dietary zinc requirement. Purified egg white diets with and without supplemental zinc were fed to channel catfish fingerlings for 12 weeks in the essentiality experiment. Catfish fed the basal diet containing 1.0 - 1.5 mg Zn/kg diet developed deficiency signs such as anorexia and suppressed growth. After week 8 of this experiment, two groups of fish fed the basal diet were converted to the zinc-supplemented diet, which contained 28 mg Zn/kg diet. Deficiency signs in these fish were alleviated after consumption of the zinc-supplemented diet. In the requirement experiment, graded levels of a zinc premix were added to egg white diets and fed to fingerling channel catfish for 14 weeks. Serum alkaline phosphatase, serum zinc, bone zinc and bone calcium data indicated that the minimum zinc requirement of fingerling channel catfish was 20 mg Zn/kg dry diet.