Influence of oxidized fish oil on the intestinal health of juvenile yellow catfish (Pelteobagrus fulvidraco) and the use of arginine as an intervention measure

This experiment was conducted to investigate the influence of dietary oxidized fish oil (OF) and the intervention of Arginine (Arg) on the intestinal health of juvenile yellow catfish. A total of 600 healthy yellow catfish (Pelteobagrus fulvidraco) with an initial body weight of (4.41±0.05) g were randomly divided into 6 groups with 4 replicates of 25 fish. During 56 d feeding trial, the fish were fed respectively six diets containing 2.5% fresh fish oil (FF), 1.5% FF+1.0% OF (OF1), 0.5% FF+2.0% OF (OF2), 2.5% FF+0.48% Arg (FFA), 1.5% FF+1.0% OF+0.48% Arg (OFA1), 0.5% FF+2.0% OF +0.48% Arg (OFA2). The results showed that the ACP, AKP activities and IL-6 content in intestine of yellow catfish were significantly higher in OF2 group. As for addition of arginine to the oxidized fish oil diets, the AKP activity and IL-6 content in intestine of yellow catfish were significantly lower in OFA2 group. The SOD activity in intestine of yellow catfish showed a downward trend and the GSH-PX and CAT activities showed a reversed trend, but there were no significant differences among FF, OF1 and OF2 groups. The SOD activity was significantly higher in OFA2 group. The MDA content in intestine of yellow catfish were significantly higher in OF2 group. Dietary oxidized fish oil and arginine had a significant interaction on the GSH-PX activity in intestine of yellow catfish. The CAT activity in intestine was significantly decreased by the arginine. The DAO activity in intestine of yellow catfish showed a downward trend and the iNOS showed an upward trend, but there was no significant difference among FF, OF1 and OF2 groups. The DAO activity significantly increased and iNOS significantly decreased in OFA2 group. The arginine had a significant impact on the DAO and iNOS activities in intestine of yellow catfish. The height of folds, the thickness of muscles and the number of goblet cells in foregut increased in OF1 group. In comparison with OF2 group, the height of folds and the number of goblet cells in foregut increased in the OFA2 group. Oxidized fish oil showed a significant influence on the height of folds. The results suggest that dietary oxidized fish oil would reduce the intestinal immune and total antioxidant capacity, and damage the structure in foregut of juvenile yellow catfish, but arginine supplementation can alleviate the inhibition induced by oxidized fish oil for intestinal immune, antioxidant capacity and tissue structure.