Nano and macro iron oxide (Fe2O3) as feed additives: Effects on growth, biochemical, activity of hepatic enzymes, liver histopathology and appetite-related gene transcript in goldfish (Carassius auratus)

The current research aimed to examine the effects of nano and macro iron oxide (Fe2O3) on growth performance, activity of hepatic enzymes, serum biochemical parameters, liver histopathology and appetite-related gene transcript in goldfish (Carassius auratus). Juvenile goldfish (4.3 g) were fed purified diets based on casein as a protein source and containing different levels of supplementary nano (0, 0.2, 0.5 and 1 g nFe(2)O(3)/kg diet) and macro iron oxide (0, 0.2, 0.5 and 1 g Fe2O3/kg diet) for 60 days. At the end of the experiments, blood, intestine and liver samples were obtained for histopathology, biochemical analysis and assays of ghrelin and IGF-I gene expression. The results showed that fish fed a diet supplemented with 0.5 g/kg Fe2O3 and nFe(2)O(3) had a significantly (P < .05) greater specific growth rates (SGR) and lower feed conversion ratios (FCR) than those fed diets of 0, 0.2 and 1 g/kg Fe2O3 and nFe(2)O(3). Furthermore, dietary Fe2O3 and nFe(2)O(3) supplementation were found to increase plasma concentrations of alkaline phosphatase (ALP) compared with the control group (P < .05) while significant differences were not found in glucose, triglyceride and total protein (P > .05). Histopathological analyses exhibited some liver lesions, including blood cell aggregation, Lipidosis, hyperemia in goldfish. The results revealed that administration of Fe2O3 significantly (P < .05) up-regulated IGF-1 and ghrelin gene expressions; these were significantly (P < .05) higher in Fe2O3-fed fish at the end of the trial. In brief, our findings indicate that both nFe(2)O(3) and Fe2O3 forms of iron have a positive effect on general physiological parameters of the fish up to supplemental level of 0.5 g/kg. Also our results showed that Fe2O3 and nFe(2)O(3) stimulate ghrelin and insulin-like growth factor-1 secretion from the intestine and liver of goldfish.