Abstract:This study was conducted to determine the effects of three forms of manganese on growth performance, antioxidant capacity, serum biochemical indexes, and intestinal morphology of juvenile hybrid grouper (). The experimental diets were isonitrogenous and isolipidic diets with the addition of manganese sulfate (MnSO4), manganese glycine (Mn-Gly), and manganese hydroxymethionine (Mn-MHA), respectively. The three groups containing manganese had 37.74 mg/kg, 40.66 mg/kg, and 38.15 mg/kg, respectively. Two hundred and seventy groupers[initial average weight (11.00±0.12) g] were randomly divided into three groups with three replicates at a stock density of 30, and fed with test diets for 8 weeks. The results showed that the weight gain rate in Mn-Gly and Mn-MHA groups were significantly higher than that of the MnSO4group. The feed coefficient rate of fish fed Mn-MHA were significantly lower than those fed MnSO4. The specific growth rate and survival rate were not significantly different among the three groups ( > 0.05). Liver malonaldehyde contents in the Mn-Gly and Mn-MHA groups were significantly lower than those in the MnSO4group. In the Mn-MHA group, the activity of manganese superoxide dismutase in the liver was significantly higher than that in the MnSO4 and Mn-Gly groups. The activity of copper-zinc superoxide dismutase in the Mn-Gly and Mn-MHA groups were significantly lower than those fed in the MnSO4group ( < 0.05). In serum, the contents of glucose in the Mn-Gly and Mn-MHA groups were significantly higher than that of the MnSO4group, the contents of cholesterol in the MnSO4 and Mn-Gly groups were significantly higher than that of the Mn-MHA group (group, the plica height of proximal and mid intestine, and the muscle thickness of distal intestine were significantly increased in the Mn-MHA group ( < 0.05). In the Mn-Gly group, the plica width of mid intestine was significantly increased comparing to that of MnSO4group, the plica height of distal intestine was significantly higher than that of the MnSO4 and Mn-MHA groups (, Mn-Gly and Mn-MHA could significantly improve the growth performance, enhance the antioxidant capacity of liver, regulate the related metabolic response, protect the liver, and promote the development of the proximal, mid, and distal intestines of juvenile hybrid grouper.
