Effects of oxidized fish oil diet supplemented with tea polyphenols on intestinal health and liver metabolism of spotted sea bass (Lateolabrax maculatus)

In this study, the effects of oxidized fish oil diet supplemented with tea polyphenols (TP) on the intestinal health and liver metabolism of spotted sea bass (Lateolabrax maculatus) were investigated. Five kinds of diets were designed. They were the negative control (NC) group without antioxidants and TP, the positive control (PC) group with antioxidants, three experimental groups were supplemented with 0.05 %, 0.10 %, and 0.15 % TP (TP1, TP2, and TP3). The fish with a mean body weight of 11.43±0.02 g was fed on five diets for 56 days. The results showed that TP1 improved lipase (LPS) activity. The intestinal superoxide dismutase (SOD) activity of TP1 was significantly higher than that of the NC group and was not different from that of the PC group. Histological observation of the intestine showed that the height of the intestinal villus was significantly increased and the width of the intestinal villus was significantly decreased in TP1, while the muscular thickness layer did not change significantly. Furthermore, inflammatory symptoms were present in the intestines of all groups, with improvements observed in TP1 and TP3. By intestinal microbial analysis, the results showed that the ACE and Chao1 indexes of TP1 were significantly higher than those of the NC and PC groups, and the Shannon and Simpson indexes were significantly lower than those of the NC and PC groups. Regarding the structure of the microbiome community, there were a lot more Fusobacteriota in TP2 and TP3 at the phylum level, and there were a lot more Cetobacterium at the genus level. The metabolomic analysis of TP1's liver showed that it controls the metabolism of amino acids, nucleotides, cofactors, vitamins, energy, and carbohydrates. The results showed that adding TP to the oxidized fish oil diet enhanced the intestinal health and liver metabolism of spotted sea bass.