Selenium nanoparticle and selenomethionine as feed additives: effects on growth performance, hepatic enzymes’ activity, mucosal immune parameters, liver histology, and appetite-related gene transcript in goldfish (Carassius auratus)

The aim of this study was to assess the effects of different dietary selenium sources, selenium nanoparticle (nSe), and selenomethionine (SeMet) as feed additives on growth performance, hepatic enzymes’ activity, biochemical, mucosal immune parameters, liver histology, and appetite-related gene transcript in goldfish ( Carassius auratus ). At first, goldfish juveniles ( n =480; mean 4.54 g) were fed dietary selenium nanoparticle at 0, 0.3, 0.6, and 0.9 mg nSe/kg diet and SeMet at 0, 0.3, 0.6, and 0.9 mg Se/kg for 9 weeks. Growth performance was evaluated using standard procedures. Blood, skin mucus, and tissue samples (liver and intestine) were collected for biochemical, mucosal immune response, histology, and ghrelin and insulin-like growth factor-I (IGF-I) gene expression. The results showed that fish fed diets fortified with 0.6 mg nSe/kg and 0.6 mg Se/kg had a significant higher weight gain, specific growth rates (SGR), and lower feed conversion ratios (FCR) than fish fed basal diets ( p