Abstract:To determine the optimal dietary selenium requirement of golden pompano (Trachinotus ovatus), a total of 450 fish with an initial body weight of (15.04±0.20) g were randomly assigned into 6 groups with 3 replicates per group and 25 fish per replicate. The fish were fed isonitrogenous and isolipidic diets with sodium selenite (Na2SeO3) as the selenium source for 50 days, which the selenium contents were 0.41, 0.60, 0.73, 0.80, 0.90 and 1.12 mg/kg, respectively. The results showed that weight gain rate and specific growth rate firstly increased and then remained stable with the increased dietary selenium content, while the feed conversion ratio had an opposite trend. No significant difference was found in the whole body composition (P>0.05). In serum, with the dietary selenium levels increasing, the contents of albumin and high density lipoprotein cholesterol firstly increased and then decreased, while the activity of alkaline phosphatase increased and then remained stable. The selenium in the feed had significant effects on the activities of glutathione peroxidase and superoxide dismutase in the serum, and glutathione peroxidase, glutathione S-transferase, glutathione reductase, catalase in the liver (P<0.05). As the dietary selenium levels increased, the activities of glutathione peroxidase, glutathione S-transferase and catalase firstly increased and then remained stable, whereas the activities of superoxide dismutase and glutathione reductase increased and then decreased. The selenium levels in feed significantly affected the selenium concentration in the whole body (P<0.05), as the dietary selenium content increased, whole body selenium concentration increased and then remained stable. Broken-line regression analysis based on the weight gain rate, serum glutathione peroxidase activity and whole body selenium concentration indicate that the optimal dietary selenium requirements for golden pompano are 0.66, 0.82 and 0.76 mg/kg, respectively.
