Effects of dietary green tea (Camellia sinensis L.) supplementation on growth performance, lipid metabolism, and antioxidant status in a sturgeon hybrid of Sterlet (Huso huso ♂ × Acipenser ruthenus ♀) fed oxidized fish oil

Effects of a Phytogenic Supplement Containing Olive By-Product and Green Tea Extracts on Growth Performance, Lipid Metabolism, and Hepatic Antioxidant Capacity in Largemouth Bass (Micropterus salmoides) Fed a High Soybean Meal Diet

A 10-week growth trial was conducted to investigate the effects of a phytogenic feed additive (PFA) containing olive by-products and green tea extracts supplemented to a reduced fishmeal/high soybean meal diet on the growth performance, hepatic antioxidant capacity, lipid metabolism, and liver health of largemouth bass (Micropterus salmoides). Three experimental diets were tested: (1) a control high fishmeal (40%) and low soybean meal (15.57%) diet (named HFM), (2) a reduced fishmeal (30%) and high soybean meal (30.97%) diet (named HSB), and (3) a HSB diet supplemented with the PFA at 500 mg/kg (named HSB+P). Each diet was assigned to four replicate tanks, each containing 30 largemouth bass (initial body weight, IBW = 48.33 ± 0.01 g). The results showed that increasing the soybean meal content in the diet did not negatively affect growth performance, whereas supplementation with PFA significantly increased weight gain and specific growth rate of largemouth bass compared to both HFM and HSB groups. Reducing fishmeal and increasing soybean meal in the diet caused oxidative stress with a higher content of ROS in the liver. However, the hepatic antioxidant capacity was enhanced, with reduced ROS and increased GSH-Px levels in the HSB+P group. Moreover, the decrease of plasma TG, LDL-C, and LDL-C/TC, and downregulation of lipogenesis and cholesterol synthesis gene expression in liver, indicated that supplementation with the PFA improved fish lipid metabolism. Protein retention efficiency was also significantly increased in largemouth bass fed the diet with PFA supplementation, which regulated (enhanced) AKT-mTOR phosphorylation. These results clearly indicated that a PFA containing olive by-product and green tea extracts can positively improve growth performance, protein retention efficiency, antioxidant capacity, and lipid metabolism of largemouth bass fed a reduced fishmeal/high soybean meal diet.

Dietary Natural Plant Extracts Can Promote Growth and Modulate Oxidative Status of Senegalese Sole Postlarvae under Standard/Challenge Conditions

Simple Summary

Oxidative stress has a direct impact on the welfare of fish, affecting growth performance and health status. Natural plant extracts present a high antioxidant capacity, due to a diversity and abundant content of polyphenols. Thus, the aim of this work was to identify if plant extracts, such as curcumin, green tea, and grape seeds, can promote oxidative status, and ultimately, enhance the growth and physiological stress response of postlarvae. Our results showed that plant extracts can improve the growth and oxidative status of the fish. Moreover, they may help fish to cope under stressful conditions. Dietary formulations with natural supplements may be a viable strategy to improve fish robustness during early life stages, and can therefore contribute to the development of aquafeeds and promote the sustainability of aquaculture production.

Abstract

Plant extracts are known for their high content and diversity of polyphenols, which can improve fish oxidative status. A growth trial with Senegalese sole postlarvae (45 days after hatching) fed with one of four experimental diets—control (CTRL), and supplemented with curcumin (CC), green tea (GT), and grape seed (GS) extracts—was performed to assess if supplementation could improve growth performance and oxidative status. At the end of the growth trial, postlarvae were submitted to a thermal stress to assess their robustness. Sole growth was improved by CC and GS diets when compared to those fed the CTRL. CC and CTRL postlarvae presented the lowest oxidative damage (lipid peroxidation and protein carbonylation values). Stress-related biomarkers (heat shock protein 70 and glutathione-S-transferase) decreased in CC fish compared to those fed the CTRL diet, which might be due to a direct antioxidant capacity. In contrast, oxidative damage increased in GT and GS sole reared in standard conditions. However, after a thermal stress, GT and GS diets prevented the increase of protein carbonylation content and the decrease of antioxidant glutathione, depending on exposure time. Overall, dietary supplementation with natural extracts modulated oxidative status and stress response after a short/long-term exposure to temperature.

Interactions of tea polyphenols with intestinal microbiota and their effects on cerebral nerves

Tea polyphenols (TP) are important functional components in tea. TP can regulate the composition of human intestinal flora, meanwhile, TP can be bio-transformed by the intestinal microbiota, resulting in relative metabolites, which prevent nerve damage, promote neurocognition, and increase resistance to oxidative stress. In recent years, cerebral nerves have become a hot topic of research, and studies have marked the importance of microbial flora and TP in protecting cerebral nerves. This paper reviews the effects of TP on intestinal microflora and the microbial degradation of TP. Furthermore, the potential effects of TP on cerebral nerves have been highlighted. PRACTICAL APPLICATIONS: Neuroscience studies are primarily focused on discerning the functional mechanism of the nervous system. The functional role of intestinal microbiota in host physiology regulation, especially neurological functions, has become a hotspot for neurological research. TP play a vital role in maintaining the steady status of intestinal flora and protecting cerebral nerve damage. An in-depth understanding of the TP and intestinal microbiota interaction, its implication on cerebral nerve protection, and the associated underlying mechanism will allow us to expand the therapeutic applications of TP.

Immuno-physiological and antioxidant responses of Siberian sturgeon (Acipenser baerii) fed with different levels of olive pomace

Nowadays, use of the natural plant derivatives as an immunostimulant in aquaculture is becoming more useful than antibiotics which are destructive to target animals, consumers, and the environment. The present study aimed to evaluate the efficacy of dietary substitution of wheat flour at 2, 5, 7.5, and 10% of olive pomace (OP₂, OP₅, OP_7.5, and OP₁₀) in some immune-physiological and antioxidant variables of yearling Siberian sturgeon (Acipenser baerii) weighing 165 ± 6.8 g at 19.1 ± 1.52 °C for 56 days. Fifteen fish per tank were randomly accommodated in triplicates per treatment and the control group was also included. No significant difference was seen in hematological indices including red blood cells (RBS) and immunocompetent cell population sizes among the treated groups (P > 0.05). Also, malondialdehyde (MDA) activity and superoxide dismutase (SOD) in serum remained unaffected in different treatments (P > 0.05). Total protein (TP), high-density lipoprotein (HDL), catalase (CT), and lysozyme were affected by dietary OP levels (P < 0.05), and the highest value was observed at the OP₅ diet, but no influence was seen in serum IgM by OP. These data show that application of olive pomace as a partial substitute of wheat flour in the diet of Siberian sturgeon is feasible with stimulatory and antioxidant functions.

Changes in growth performance, haematological parameters, hepatopancreas histopathology and antioxidant status of pacific white shrimp (Litopenaeus vannamei) fed oxidized fish oil: Regulation by dietary myo-inositol

A 58-day feeding trial was conducted to evaluate the effects of dietary myo-inositol (MI) supplementation on growth performance, haematological parameters, hepatopancreas histopathology and antioxidant status of Litopenaeus vannamei fed with oxidized fish oil (OFO). Control diet contained fresh fish oil (FFO) without MI supplementation. The other four diets contained two oxidation levels of OFO (peroxide value: 133.2 and 268.7 meq kg^-1) with or without 200 mg MI kg^-1 diets (MI0+L, MI0+H, MI200 + L and MI200 + H). Results showed that OFO-supplemented groups (without MI supplementation) showed better growth performance and lower whole-body inositol content when opposed to control group. MI supplementation significantly improved whole-body inositol content in high-oxidized fish oil (HOFO) groups, and also reduced whole-body lipid in low-oxidized fish oil (LOFO) groups. Moreover, Supplementation of OFO and MI markedly hit the fatty acid profile of muscle. HOFO caused severe histopathological changes in hepatopancreas of shrimp, which slightly alleviated by MI supplementation. MI supplementation also grew the total protein (TP) content and alkaline phosphatase (AKP) activity and decreased the activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of serum in OFO-supplemented groups. Ingestion of OFO increased levels of lipid peroxidation and protein oxidation in serum or hepatopancreas, which partly ameliorated by MI supplementation. Activities of antioxidant enzymes exhibited different expression patterns because of OFO and MI. In addition, HOFO markedly increased mRNA expression levels of antioxidant genes including ferritin (FT), thioredoxin (Trx), GPX, glutathione S-transferase (GST) and catalase (CAT) and decreased peroxiredoxin (Prx) expression, in which expression of GPX and Prx were increased owing to MI supplementation. Therefore, it suggested that dietary OFO stimulated growth performance, but also induced oxidative stress and caused impairment to hepatopancreas in L. vannamei. The negative impact brought about by OFO was partially mitigated by dietary MI supplementation.