Effect of Nano Zinc as a Diet supplementation on Erythrocyte Indices of Rainbow Trout Fingerlings (Oncorhynchus mykiss Walbaum 1792)

This study was aimed to evaluate the impact of Nano Zn as dietary zinc source on hematological parameters of rainbow trout including red blood cell (RBC) count and indices. Total number of 900 rainbow trout (17.22±5.41 g) fingerlings were randomly distributed in triplicates among six treatments and adapted to the farm conditions for 2 days. The basal diet were contained no amount of zinc supplementation and considered as the control treatment. The experimental diets were prepared by adding 10, 30, 50 and 70 mg of Nano zinc (40-60 nm diameters) and 70 mg zinc sulfate per each kg of basal diet. The fish specimens were fed for 8 weeks with the relevant diet of each treatment and their erythrocyte properties were consider at the end of experiment. The results showed that fish in the 50 mg kg-1 Nano ZnO treatment had the maximum of hemoglobin, hematocrit, mean corpuscular hemoglobin (MCH) compared to other treatments. The largest numbers of RBCs followed by the mean corpuscular hemoglobin concentration (MCHC) were also found in the 30 mg kg-1 Nano ZnO treatment, although showed no significant difference with the 50 mg kg-1 Nano ZnO treatment. Findings of the current study indicated that erythrocyte indices of rainbow trout fingerlings could be improved by the Nano Zn supplementation as a new form of physical structure of metal elements.