Evaluation of quercetin in alleviating the negative effects of high soybean meal diet on spotted sea bass Lateolabrax maculatus.

The aim of this study was to investigate the effects of quercetin (QUE) on alleviating the negative effects of high soybean meal diet for spotted sea bass Lateolabrax maculatus. A healthy control group fed a 44% fishmeal diet was used, while the induction control group replaced 50% fishmeal with soybean meal. Subsequently, QUE was added at concentrations of 0.25, 0.50, 0.75, and 1.00 g/kg in the experimental groups. A total of 540 tailed spotted sea bass were randomly divided into 6 groups and fed the corresponding diet for 56 days. The results showed that 40% soybean meal significantly decreased the growth performance and immunity, increased the intestinal mucosal permeability, and caused damage to the intestinal tissue morphology; moreover, there were alterations observed in the composition of the intestinal microbiota, accompanied by detectable levels of saponins in the metabolites. However, the addition of QUE did not yield significant changes in growth performance; instead, it notably reduced the permeability of the intestinal mucosa, improved the body's immunity and the structural integrity of the intestinal tissue, increased the proportion of Proteobacteria, and enhanced the richness and diversity of intestinal microorganisms to a certain extent. In addition, QUE up-regulate the metabolism of amino acids and their derivatives and energy-related metabolites such as uridine and guanosine; furthermore, it appears to regulate transporters through the ABC transporters pathway to promote the absorption and utilization of QUE by enterocytes.

Effects of Lycium barbarum polysaccharides supplemented to high soybean meal diet on immunity and hepatic health of spotted sea bass Lateolabrax maculatus.

High soybean meal diet (HSBMD) decreased the immunity and damaged the liver health of spotted sea bass; in this study, Lycium barbarum polysaccharides (LBP) was added to HSBMD to explore its effects on the immunity and liver health. The diet with 44% fish meal content was designed as a blank control. On this basis, soybean meal was used to replace 50% fish meal as HSBMD, and LBP was added in HSBMD in gradient (1.0, 1.5, 2.0 g/kg) as the experimental diet. 225-tailed spotted sea bass with initial body weight of 44.52 ± 0.24 g were randomly divided into 5 groups and fed the corresponding diet for 52 days, respectively. The results show that: after ingestion of HSBMD, the immunity of spotted sea bass decreased slightly and hepatic tissue was severely damaged. And the addition of LBP significantly improved the immune capacity and protected the hepatic health. Specifically, the activities of serum lysozyme (LZM), immunoglobulin M (IgM), liver acid phosphatase (ACP) and alkaline phosphatase (AKP) were increased, and serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities were significantly decreased, and hepatic morphology was improved. In the analysis of transcriptome results, it was found that toll-like receptor 3 (TLR3) and toll-like receptor 5 (TLR5) were down-regulated in toll-like receptor signaling pathway. And LBP may protect hepatic health by regulating Glycolysis/Gluconeogenesis, Insulin signaling pathway, Steroid biosynthesis and other glucolipid-related pathways. In conclusion, the addition of LBP in HSBMD can improve the immunity and protect the hepatic health of spotted sea bass, and its mechanism may be related to glucose and lipid metabolism.

Effects of Mulberry Leaf Extract on the Liver Function of Juvenile Spotted Sea Bass (Lateolabrax maculatus).

In order to explore the effect of mulberry leaf extract (ELM) on the liver function of spotted sea bass, 360 fish with healthy constitution (average body weight 9.00 ± 0.02 g) were selected and randomly divided into six groups with three repetitions, and six groups of fish were randomly placed into 18 test tanks (200 L) with 20 fish per tank for the 52-day feeding test. Every day, the fish were fed the experimental feed with different concentrations (0, 3, 6, 9, 12, 15 g/kg) to the level of apparent satiation, with a crude protein content of 48.0% and a crude fat content of 8.6%. And the water temperature was maintained at 25-28°C with a salinity of 0.5%-1‰. After feeding, five fish were randomly selected to collect their livers and serum for detection of indicators. The results showed that, compared with the control group, ELM significantly increased the activities of lipase (LPS) and trypsin (TRS) in the liver, and reached the highest level when the amount of ELM added was 6 g/kg (P < 0.05). ELM significantly increased the activities of lactate dehydrogenase (LDH) and glutamic-oxaloacetic transaminase (GOT) involved in the metabolic process in liver tissue, and GOT activity reached the highest when ELM was added at 9 g/kg, and LDH activity reached the highest when ELM was added at 15 g/kg (P < 0.05). ELM had no significant effect on liver antioxidant enzymes (P > 0.05), but the content of malondialdehyde was significantly reduced (P < 0.05). Compared with the control group, ELM significantly increased the activities of AKP and ACP in the liver, and the AKP activity reached the highest when the ELM addition amount was 3 g/kg, and the ACP activity reached the highest when the ELM addition amount was 9 g/kg (P < 0.05). Through comparative transcriptomic analysis, it was indicated that ELM enhanced the hepatic lipids and carbohydrates metabolism ability, as manifested in the upregulation of expression of phosphatidate phosphatase, glucuronosyltransferase, inositol oxygenase, carbonic anhydrase, and cytochrome c oxidase subunit 2. ELM can also increase the expression of signal transducer and activator of transcription 1, ATP-dependent RNA helicase and C-X-C motif chemokine 9 involved in the immune process. The above results show that the ELM can enhance the digestion, metabolism, and immunity of the liver by increasing the activity of digestive enzymes, metabolic enzymes, and the expression of metabolism and immune regulation genes. This study provides a theoretical basis for the application of ELM in the cultivation of spotted sea bass by exploring the effect of ELM on the liver function of spotted sea bass.

Effect of Supplementation of Chlorogenic Acid to High-Fat Diet on Growth, Lipid Metabolism, Intestinal and Hepatic Histology, and Gut Microbiota of Spotted Sea Bass (Lateolabrax maculatus).

The study investigated the impact of chlorogenic acid (CGA) supplementation in a high-fat diet (HFD) on growth, lipid metabolism, intestinal and hepatic histology, as well as gut microbiota in spotted sea bass. A total of 540 fish were fed six experimental diets, including a normal fat diet (NFD), a high-fat diet (HFD), and HFD supplemented with 100, 200, 300, and 400 mg/kg CGA (named HFD1, HFD2, HFD3, and HFD4, respectively) for 7 weeks. The results showed that HFD feeding increased growth and hepatic lipid deposition compared to that in the NFD group. Inclusion of 300 mg/kg CGA in HFD decreased the HFD-induced hyperlipemia (p < 0.05). Additionally, compared to the HFD group, the HFD4 group showed significant reductions in serum aspartate transaminase (AST) and alanine transaminase (ALT) levels as well as hepatic malondialdehyde (MDA) content, while also improving liver total antioxidant capacity (T-AOC) (p < 0.05). In the CGA-containing groups, hepatocytes were arranged more neatly than those in the HFD group, and there was a reduction in lipid deposition and hemolysis in the liver. Supplementation of CGA had effects on intestinal structure including an increase in mucosal thickness, as well as villus number and width. The diversity of intestinal flora in the CGA-containing groups was higher than those in the HFD group, and supplementation of 200 mg/kg CGA significantly increased the abundance of intestinal bacteria (p < 0.05). HFD4 feeding increased the intestinal Bacteroidetes to Firmicutes ratio and decreased the abundance of Vibrio. The highest value abundance of Actinobacteriota was found in the HFD2 group. Overall, HFD caused negative effects, and supplementation of 200-400 mg/kg CGA to HFD improved fat deposition, lipid metabolic disorders and liver and gut histology, and increased gut bacterial diversity in spotted sea bass.

Effects of dietary Clostridium butyricum on the growth performance, digestion, and intestinal health of spotted sea bass (Lateolabrax maculatus).

Clostridium butyricum (CB) is known to promote growth, enhance immunity, promote digestion, and improve intestinal health. In this study, we investigated the effects of CB in the feed on growth performance, digestion, and intestinal health of juvenile spotted sea bass. To provide a theoretical basis for the development and application of CB in the feed of spotted sea bass, a total of 450 spotted sea bass with an initial body weight of (9.58 ± 0.05) g were randomly divided into six groups. Gradient levels with 0, 0.1%, 0.2%, 0.3%, 0.4%, and 0.5% of CB (1×109 cfu/g) were supplemented into diets, designated as CC, CB1, CB2, CB3, CB4, and CB5, respectively. Each group was fed for 54 days. Our results suggest that dietary 0.2% and 0.3% of CB can significantly increase the weight gain (WG) and specific growth rate (SGR) of spotted sea bass. The addition of CB significantly increased intestinal amylase activity, intestinal villus length, intestinal villus width, and intestinal muscle thickness. Similarly, CB supplementation increased the expression of tumor necrosis factor-α (TNF-α) and interleukin-8 (IL-8). Sequence analysis of the bacterial 16S rDNA region showed that dietary CB altered the intestinal microbiota profile of juvenile spotted sea bass, increasing the dominant bacteria in the intestine and decreasing the harmful bacteria. Overall, dietary addition of CB can improve growth performance, enhance intestinal immunity, improve intestinal flora structure, and comprehensively improve the health of spotted sea bass.

Integrated biomarker parameters response to the toxic effects of high stocking density, CuSO4, and trichlorfon on fish and protective role mediated by Angelica sinensis extract.

The present study explored the protective role of dietary the extract of Angelica sinensis (EAs) on high density, CuSO4, or trichlorfon-treated Crucian carp (Carassius auratus auratus). Firstly, the study showed that the optimum density for growth and growth inhibition was 0.49 and 0.98 fish L-1 water, respectively. Dietary EAs relieved the high density-induced growth inhibition in Crucian carp. The appropriate concentration of EAs for recovery of growth was estimated to be 4.30 g kg-1 diet in high-density fish. Moreover, high density decreased both digestive and absorptive enzyme activities and increased lipid oxidation in digestive organs, suggesting the ability of high density to induce oxidative damage. However, dietary EAs inhibited the oxidative damage through elevating ROS scavenging ability and enzymatic antioxidant activity in digestive organs. Secondly, our data demonstrated that the appropriate concentration of CuSO4 to induce the decrease in feed intake (FI) was 0.8 mg Cu L-1 water. Dietary EAs returned to FI of Crucian carp treated with CuSO4. The appropriate concentration of EAs for recovery of FI was estimated to be 4.25 g kg-1 diet. Moreover, dietary EAs suppressed the CuSO4-induced decrease in digestion and absorption capacity and increase in protein metabolism in digestive organs of Crucian carp. Finally, the present results suggested that dietary EAs inhibited the trichlorfon-induced rollover (loss of equilibrium) in Crucian carp. The appropriate concentration of EAs for inhibition of rollover was estimated to be 4.18 g kg-1 diet. Moreover, trichlorfon stimulated not only the decrease in energy metabolism but also lipid and protein oxidation, suggesting that trichlorfon caused loss of function and oxidative damage in muscles of fish. However, dietary EAs improved muscular function and inhibited oxidative damage via quenching ROS and elevating non-enzymatic and enzymatic antioxidant activity in muscles of trichlorfon-induced fish. So, EAs could be used as an inhibitor of high density, CuSO4, and trichlorfon stress in fish.

The effects of ethoxyquin and Angelica sinensis extracts on lipid oxidation in fish feeds and growth, digestive and absorptive capacities and antioxidant status in juvenile red carp (Cyprinus carpio var. xingguonensis): a comparative study.

Firstly, a linoleic and linolenic acid emulsion and fish feeds were incubated with graded levels of ethoxyquin (EQ) and petroleum ether extract, ethyl acetate extract (EAE), ethanol extract and aqueous extract of Angelica sinensis. The results showed that EQ and extracts of Angelica sinensis (EAs) inhibited lipid oxidation in material above. Of all of the examined EAs, EAE showed the strongest protective effects against the lipid oxidation. Moreover, EAE at high concentrations showed a stronger inhibitory effect on lipid oxidation than that of EQ. Next, 7 experimental diets that respectively supplemented 0.0, 0.2, 0.8 and 3.2 g kg-1 of EQ and EAE were fed to 280 juvenile red carp (Cyprinus carpio var. xingguonensis) with seven treatment groups for 30 days. The results indicated that dietary EAE improved growth performance in carp. Moreover, dietary EAE increased the activities of trypsin, lipase, alpha-amylase, alkaline phosphatase, glutamate-oxaloacetate transaminase and glutamate-pyruvate transaminase (GPT) and decreased plasma ammonia content in carp. Meanwhile, dietary EAE reduced the levels of malondialdehyde and raised the activities of anti-superoxide anion, anti-hydroxyl radical, superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase and the content of reduced glutathione in the hepatopancreas and intestine of carp. However, with the exception of GPT, dietary EQ got the opposite results to dietary EAE in carp. These results revealed that dietary EAE improved the digestive, absorptive and antioxidant capacities in fish. However, dietary EQ inhibited the digestive, absorptive and antioxidant capacities in fish. So, EAE could be used as a natural antioxidant for replacing EQ in fish feeds.