Dietary zinc requirement of Siberian sturgeon (Acipenser baerii, Brandt 1869) juveniles, based on the growth performance and blood parameters

This study investigated the effect of dietary Zn levels on growth performance, feed utilization, and hematological parameters of juvenile Siberian sturgeon (Acipenser baerii, Brandt 1869). The five semipurified diets were formulated by adding 0, 5, 10, 20, and 40 mg Zn kg-1 diet in the form of zinc sulfate (ZnSO4) to provide the actual dietary value of 14.7, 20.8, 27.3, 37.7, and 46.4 Zn kg-1 diet, respectively. The results showed that dietary Zn elevating level significantly improved the growth and feed utilization of the fish (p<0.05), but not the hepatosomatic index (p>0.05). Erythrocyte number, hemoglobin concentration, and hematocrit were increased with raising dietary Zn level (p<0.05), whereas a regular trend was not observed in blood indices, including MCV, MCH, and MCHC. A significant increase was also found in the leucocyte number followed by their differential counts, except for eosinophil percentage. The broken line regression model indicated optimal dietary Zn level for growth maximization of fish was estimated to be 29.15 mg Zn kg-1 diet. In spite of well correlation with dietary Zn level, no break point was observed to estimate the juvenile Siberian sturgeon requirement based on the erythrocyte numbers.