The hematological improvement of rainbow trout (Oncorhynchus mykiss) during dietary supplementation with vitamin C after exposure to zinc nano-particles

The aim of this study was to examine the adverse effects of zinc nanoparticles on hematological indices of trout and investigate the improvement of these indices after vitamin C treatments. This study assesses the protective role of vitamin C in fish exposed to ZnO NPs. Two concentrations of ZnO-NPs (۴۰ and ۸۰ mg L-۱) and two doses of vitamin C (۴۰۰ and ۸۰۰ mg per kg of feed) were used to treat ۱۶۲ specimens of Oncorhynchus mykiss. No mortality was observed during the test. After ۵ and ۱۰ days of exposure, hematological data were analyzed according to routine clinical methods. Statistical analysis showed significant changes in WBCs and RBC on day ۱۰ (p<۰.۰۵). Values for HT and MCH were significantly higher in treatment ۲ (normal diet+۴۰ mg L-۱ ZnO-NPs) and ۹ (۸۰۰ mg/kg Vit + ۸۰ mg L-۱ ZnO-NPs), and lower in treatment ۳ (normal diet+۸۰ mg L-۱ ZnO-NPs) in comparison with the control group (normal diet+۰ mg L-۱ ZnO-NPs) (P<۰.۰۵). No significant differences of MCV and MCHC were observed (p>۰.۰۵), while significant increase in neutrophils and monocytes, and decrease in lymphocyte cells were recorded (p<۰.۰۵). ZnO-NPs stimulated the immune system of O. mykiss, but this effect did not have any lethality on this species at ۴۰ and ۸۰ mg L-۱. Vitamin C in different concentrations could help to prevent rainbow trout from the toxic effects of this nano metal. 

Keywords:

Fish , Hematology , Nano particle , Toxicity , Vitamin C