Influences of dietary Eucommia ulmoides extract on growth, flesh quality, antioxidant capacity and collagen-related genes expression in grass carp (Ctenopharyngodon idellus)

Eucommia ulmoides leaf extracts combined with Astragalus polysaccharides: Effects on growth, antioxidant capacity, and intestinal inflammation in juvenile large yellow croaker (Larimichthys crocea)

Eucommia ulmoides leaf extract (ELE) and Astragalus polysaccharides (APS) have been widely used as immunopotentiators in aquaculture. Our prior research on large yellow croaker (Larimichthys crocea) demonstrated that dietary 1 g/kg APS bolstered fish immunity and antioxidant defense. However, the combined effect of ELE and APS in juvenile large yellow croaker remains unknown. Hence, this study aimed to investigate the synergistic effect of ELE and APS on the growth, antioxidant capacity, and intestinal inflammation in large yellow croaker. A total of 1200 fish were divided into five groups and fed diets with 1 g/kg APS and varying ELE levels: 0 g/kg (ELE0), 0.25 g/kg (ELE0.25), 0.5 g/kg (ELE0.5), 1 g/kg (ELE1), and 2 g/kg (ELE2). After an 8-week feeding period, the ELE0.5 and ELE1 groups showed superior weight gain rate, specific growth rate, and feed efficiency compared to other groups. The ELE1 group also had elevated trypsin and lipase activities in the intestine, whereas α-amylase activity was not influenced by ELE addition. Antioxidant enzyme activities, such as hepatopancreas superoxide dismutase (SOD) and glutathione peroxidase (GPX) in the ELE1 group were significantly enhanced, while malondialdehyde (MDA) levels decreased with increasing ELE. Intestinal morphology revealed the highest villi height in proximal and distal intestines of ELE1 group, with no significant change in mucosal thickness. In terms of cytokines, the ELE1 group showed significant down-regulation of pro-inflammatory (tnf-α, il-1β and il-6) and up-regulation of anti-inflammatory (il-4/13a, il-10 and tgf-β) markers, modulated by MAPK and mTOR signaling. In conclusion, this study indicates that supplementing diets with 1 g/kg ELE alongside 1 g/kg APS in juvenile large yellow croaker offers the best synergistic effect on fish immunity, including enhanced growth, antioxidant capacity, and relieved intestinal inflammation through MAPK and mTOR signaling.

Dietary Hydroxyproline + Vitamin C and Eucommia ulmoides Improved the Growth and Flesh Quality of Pacific White Shrimp (Litopenaeus vannamei)

Pacific white shrimp (Litopenaeus vannamei) is an important aquaculture shrimp in China and globally due to its high nutritional value and delicious flavors [...].

Dietary supplementation with succinic acid improves growth performance and flesh quality of adult Nile tilapia (Oreochromis niloticus) fed a high-carbohydrate diet

To evaluate the effects of dietary supplementation with succinic acid on growth performance, flesh quality, glucose, and lipid metabolism of Nile tilapia (Oreochromis niloticus) fed a high-carbohydrate diet (HCD), five iso-nitrogenous and iso-lipidic diets were prepared as follows: HCD (control group) consisting of 55% corn starch and HCD supplemented with 0.5%, 1.0%, 2.0%, and 4.0% succinic acid, respectively. Tilapia with an initial body weight of 204.90 ± 1.23 g randomly assigned to 15 tanks with 3 replicates per group and 10 fish per tank fed for 8 weeks. Increasing dietary succinic acid supplementation resulted in significant second-order polynomial relationship in the weight gain rate (WGR), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency rate (PER), viscerosomatic index, condition factor, and contents of muscular crude lipid and glycogen (P < 0.05). The hepatosomatic index, mesenteric fat index, liver glycogen content and crude lipid contents of the whole-body and liver demonstrated significantly linear and second-order polynomial relationship (P < 0.05). Quadratic curve model analysis based on WGR, SGR, PER, and FCR demonstrated that optimal supplementation with succinic acid in the HCD of Nile tilapia ranged from 1.83% to 2.43%. Fish fed with 1.0% succinic acid had higher muscular hardness, increased the contents of alkali-soluble hydroxyproline in collagen, docosahexaenoic acid (DHA) and n-3 polyunsaturated fatty acid (n-3PUFA) in muscle, and lower total fatty acid content in muscle (P < 0.05) compared with the control group. Compared to the control group, dietary supplementation with 1.0% succinic acid significantly increased the contents of total bounding amino acid (arginine, histidine, isoleucine, lysine, methionine, alanine, proline), total flavor amino acid (free aspartic acid), the catalase (CAT) activity and total antioxidant capacity, and the mRNA relative expression levels of CAT, superoxide dismutase (SOD), and nuclearfactor erythroidderived 2-like 2 (Nrf2) in muscle (P < 0.05). Furthermore, succinic acid supplementation significantly up-regulated mRNA relative expression levels of glycolysis genes (hexokinase 2 [HK2], phosphofructokinase, muscle-A [PFKMA], and phosphofructokinase, muscle-B [PFKMB]), a key glycogen synthesis gene (glycogen synthase [GYS]), and lipid catabolism genes (carnitine palmitoyltransferase-1B [CPT1B], hormone sensitive lipase [HSL], and lipoprotein lipase [LPL]), while down-regulating the mRNA relative expression level of fatty acid synthase (FASN) in muscle (P < 0.05). In conclusion, dietary supplementation with 1.83% to 2.43% succinic acid improved muscle quality by increasing muscle antioxidant capacity and hardness, changing muscle amino acid and fatty acid composition, and regulating muscle glucose and lipid metabolism.

Biochemical, Histological, and Transcriptomic Analyses Reveal Underlying Differences in Flesh Quality between Wild and Farmed Ricefield Eel (Monopterus albus)

The present study aimed to systematically investigate the underlying differences in flesh quality between wild and farmed Monopterus albus. Fifteen healthy M. albus per group with an average body weight of 45 g were sampled to analyze muscle parameters by biochemical indicators, histomorphology, and molecular biology. Compared with the wild fish, the farmed M. albus in flesh had lower crude protein, collagen, lysine, histidine, total amino acids, SFA, n-3 PUFA contents, and n-3/n-6 ratio (p < 0.05), and higher moisture, crude lipid, crude ash, MUFA, n-6PUFA, and total PUFA contents (p < 0.05). The thawing loss, drip loss, steaming loss, and boiling loss in the farmed group were significantly higher, and hardness, springiness, cohesiveness, gumminess, chewiness, and resilience were significantly lower than those in the wild group (p < 0.05). In addition, higher muscle fiber density and lower muscle fiber diameter were observed in wild M. albus (p < 0.05). In muscle transcriptome profiling, differentially expressed genes and enriched pathways are primarily associated with muscle development, protein synthesis, catabolism, lipid metabolism, and immunity. To the best of our knowledge, this is the first investigation that compares the flesh quality between wild and farmed M. albus in terms of biochemistry, histology, and molecular biology levels. Overall, wild M. albus had a higher nutritional value and texture quality than farmed M. albus.

(-)-Epigallocatechin-3-O-Gallate Regulates Muscle Growth, Antioxidant Status, and Nutritional Composition of Juvenile Common Carp (Cyprinus carpio L.)

Among the polyphenolic compounds commonly found in green tea, (-)-epigallocatechin-3-gallate (EGCG) is known to have various functions, including the promotion of antioxidant and myofiber growth in mammals. However, the effect of EGCG on common carp (Cyprinus carpio L.) remains poorly understood. To evaluate the role of EGCG on juvenile common carp, 255 fish (initial weight 17.33 ± 0.34 g) were fed with five experimental diets containing 0, 0.05, 0.25, 0.5, and 1 g/kg EGCG. The results showed that diet supplementation with 0.05-0.5 g/kg EGCG supplementation significantly enhanced the specific growth rate (SGR) and reduced the feed conversion ratio (FCR). Weight gain rate (WGR) was significantly enhanced in the 0.25 and 0.5 g/kg EGCG groups. As for antioxidants, 0.25-1 g/kg EGCG significantly reduced protein carbonyl (PC) content and upregulated superoxide dismutase (sod) gene expression in the muscle. As for muscle nutritional composition, 0.05-0.5 g/kg EGCG increased total amino acid (TAA) and flavor amino acid (FAA) contents, likely via the rapamycin (mTOR) signaling pathway. Muscle n-3 polyunsaturated fatty acids (n-3 PUFA) content was increased with 0.5 g/kg EGCG, presumably owing to the upregulation of fatty acyl elongase 5 (elovl5), long-chain fatty acyl-CoA synthetase 6 (acsl6), and peroxisome proliferator-actiated receptor α (pparα). Dietary EGCG (0.05-1 g/kg) significantly increased muscle hardness and chewiness, accompanied by an increase in myofiber density. EGCG supplementation (0.25-1 g/kg) increased the pH value and reduced lactate contents in the muscle. However, muscle crude lipid and hydroxyproline contents significantly decreased with 1 g/kg EGCG. Overall, quadratic regression analysis of WGR, SGR, TAA, and FAA showed that optimal EGCG (0.46-0.52 g/kg) dietary supplementation improved the growth and nutritional composition of juvenile common carp.

Effects of Five Lipid Sources on Growth, Hematological Parameters, Immunity and Muscle Quality in Juvenile Largemouth Bass (Micropterus salmoides)

This study investigated the effects of fish oil (FO), soybean oil (SO), rapeseed oil (RO), peanut oil (PO) and lard oil (LO) on growth, immunity and muscle quality in juvenile largemouth bass. After 8 weeks, the results showed that FO and RO could increase weight gain and serum alkaline phosphatase and apelin values compared with LO (p < 0.05). Except lower crude lipid contents, higher amounts of n-3 polyunsaturated fatty acids (15.83% and 14.64%) were present in the dorsal muscle of the FO and RO groups. Meanwhile, FO and RO could heighten mRNA levels of immune defense molecules (lysozyme, hepcidin, and transforming growth factor β1) compared with PO (p < 0.05). While SO could increase potential inflammatory risk via rising counts of white blood cells, platelets, neutrophils and monocytes, and mRNA levels of interleukins (IL-1β, IL-8, IL-12 and IL-15), FO and RO could improve hardness, chewiness and springiness through increasing amounts of hydroxyproline, collagen and lysyl oxidase, and mRNA levels of collagen 1α2 and prolyl hydroxylase in the fish dorsal muscle. Moreover, FO and RO could improve firmness through increasing glycogen and glycogen synthase 1 levels when compared with LO (p < 0.05). Therefore, these results could provide dietary lipid source references during the feeding process of adult largemouth bass.

Analysis of chemotypes and their markers in leaves of core collections of Eucommia ulmoides using metabolomics

The leaves of Eucommia ulmoides contain various active compunds and nutritional components, and have successively been included as raw materials in the Chinese Pharmacopoeia, the Health Food Raw Material Catalogue, and the Feed Raw Material Catalogue. Core collections of E. ulmoides had been constructed from the conserved germplasm resources basing on molecular markers and morphological traits, however, the metabolite diversity and variation in this core population were little understood. Metabolite profiles of E. ulmoides leaves of 193 core collections were comprehensively characterized by GC-MS and LC-MS/MS based non-targeted metabolomics in present study. Totally 1,100 metabolites were identified and that belonged to 18 categories, and contained 120 active ingredients for traditional Chinese medicine (TCM) and 85 disease-resistant metabolites. Four leaf chemotypes of the core collections were established by integrated uses of unsupervised self-organizing map (SOM), supervised orthogonal partial least squares discriminant analysis (OPLS-DA) and random forest (RF) statistical methods, 30, 23, 43, and 23 chemomarkers were screened corresponding to the four chemotypes, respectively. The morphological markers for the chemotypes were obtained by weighted gene co-expression network analysis (WGCNA) between the chenomarkers and the morphological traits, with leaf length (LL), chlorophyll reference value (CRV), leaf dentate height (LDH), and leaf thickness (LT) corresponding to chemotypes I, II, III, and IV, respectively. Contents of quercetin-3-O-pentosidine, isoquercitrin were closely correlated to LL, leaf area (LA), and leaf perimeter (LP), suggesting the quercetin derivatives might influence the growth and development of E. ulmoides leaf shape.

Dietary ribose supplementation improves flesh quality through purine metabolism in gibel carp (Carassius auratus gibelio)

Since the aquaculture industry is currently observing a deterioration in the flesh quality of farmed fish, the use of nutrients as additives to improve the flesh quality of farmed fish species is a viable strategy. The aim of this study was to investigate the effect of dietary D-ribose (RI) on the nutritional value, texture and flavour of gibel carp (Carassius auratus gibelio). Four diets were formulated containing exogenous RI at 4 gradient levels: 0 (Control), 0.15% (0.15RI), 0.30% (0.30RI) and 0.45% (0.45RI). A total of 240 fish (150 ± 0.31 g) were randomly distributed into 12 fibreglass tanks (150 L per tank). Triplicate tanks were randomly assigned to each diet. The feeding trial was carried out in an indoor recirculating aquaculture system for 60 d. After the feeding trial, the muscle and liver of gibel carp were analysed. The results showed that RI supplementation did not result in any negative impact on the growth performance and 0.30RI supplementation significantly increased the whole-body protein content compared to the control group. The contents of collagen and glycogen in muscle were enhanced by RI supplementation. The alterations in the flesh indicated that RI supplementation improved the texture of the flesh in terms of its water-holding capacity and hardness, therefore improving the taste. Dietary RI facilitated the deposition of amino acids and fatty acids in the muscle that contributed to the meaty taste and nutritional value. Furthermore, a combination of metabolomics and expression of key genes in liver and muscle revealed that 0.30RI activated the purine metabolism pathways by supplementing the substrate for nucleotide synthesis and thereby promoting the deposition of flavour substance in flesh. This study offers a new approach for providing healthy, nutritious and flavourful aquatic products.

The comparison of largemouth bass (Micropterus salmoides) fed trash fish and formula feeds: Growth, flesh quality and metabolomics

This study compared the growth, flesh quality and metabolomics of largemouth bass (Micropterus salmoides) fed trash fish and formula feeds. Trash fish (TF), self-made feed (SF) and commercial feed (CF) were prepared with crude protein levels of 172.2 g/kg, 503.5 g/kg and 504.1 g/kg (666.2 g/kg, 547.3 g/kg and 535.1 g/kg based on dry matter), respectively. Then, the three diets were fed to largemouth bass with an initial body weight of 75.0 ± 0.1 g for 12 weeks. SF and CF groups presented significantly lower feed intake (FI), feed conversion ratio (FCR) and higher protein efficiency ratio (PER) than TF group based on dry matter basis without affecting the weight gain (P &lt; 0.05). The yellowness (b*) in dorsal muscle, flesh heat-insoluble collagen and free flavor amino acids contents in SF group were significantly higher (P &lt; 0.05), while drip loss were significantly lower (P &lt; 0.05) than those of TF group. Compared to TF group, SF and CF groups showed significantly higher flesh polyunsaturated fatty acids (PUFAs), n-3 PUFAs and n-6 PUFAs contents, flesh hardness, shear force and muscle fiber density (P &lt; 0.05), and lower flesh total free amino acids, essential amino acids, muscle fiber diameter, intestine villus height and muscular thickness (P &lt; 0.05). The serum total protein, triglyceride and cholesterol levels in SF group were significantly lower than those in TF and CF groups (P &lt; 0.05). In the muscle metabolomics, 177 differential metabolites were detected between SF and TF groups, which mainly enriched in pathways as biosynthesis of amino acid, histidine metabolism, glycine, serine and threonine metabolism, etc. Conclusively, feeding largemouth bass with formula feeds improved flesh fatty acid profile and flesh texture without negative effects on the growth, but the flesh free amino acids contents were lower than the fish fed trash fish.

In vitro effects of Eucommia ulmoides and its active components on the growth, lipid metabolism and collagen metabolism of grass carp (Ctenopharyngodon idellus) hepatocyte and intramuscular fibroblast

Two experiments were conducted to investigate the in vitro effects of Eucommia ulmoides (E. ulmoides) and its active components on the growth, lipid metabolism and collagen metabolism of grass carp's (Ctenopharyngodon idellus) hepatocytes and intramuscular fibroblasts. In experiments 1 and 2 (Expt. 1, 2), hepatocytes and intramuscular fibroblasts were treated with 2.5, 5, 10, 20, 40 and 80 μg ml^-1 of Eucommia bark extract (EBE), Eucommia leaf extract (ELE), pinoresinol diglucoside (PDG), chlorogenic acid (CGA), quercetin (QC) and aucubin (AU) for 24 h, respectively, then the cell growth, lipid and collagen metabolism-related gene expressions were evaluated. The results showed that the cell proliferation rate of hepatocytes and intramuscular fibroblasts was significantly improved by the supplementation of EBE, ELE, CGA, QC and AU. Moreover, triglyceride concentration of hepatocytes was significantly decreased by the EBE, ELE, CGA and QC supplementations compared to the control. Meanwhile, EBE, ELE, CGA, QC and AU supplementations significantly upregulated the relative gene expressions of insulin-like growth factor-1 (igf1), protein kinase B (akt), target of rapamycin (tor) and eukaryotic initiation factor 4E binding protein 1 (4ebp1) in hepatocytes, and ribosomal protein S6 kinase 1 (s6k1) transcription was significantly activated by ELE, CGA and QC supplementations. Nonetheless, phosphatidylinositol 3-kinase (pi3k) was unaffected by any of the supplements. In addition, the mRNA expressions of genes associated with lipid metabolism (peroxisome proliferator activated receptor α pparα, carnitine palmitoyltransferase 1 cpt1, adipose triglyceride lipase atgl, hormone-sensitive lipase hsl, peroxisome proliferator activated receptor γ pparγ) were significantly upregulated by EBE, ELE, CGA and QC. In intramuscular fibroblasts, the EBE, ELE, CGA, QC and AU supplementations significantly increased in vitro hydroxyproline concentrations, promoted the relative expressions of transforming growth factor-β1 (tgfβ1), connective tissue growth factor (ctgf), collagen type I alpha 1/2 chain (col1a1, col1a2), lysine oxidase (lox) and tissue inhibitor of matrix metalloproteinase-2 (timp2), and decreased matrix metalloproteinase-2 (mmp2) gene expression. Also, the gene expressions of drosophila mothers against decapentaplegic protein 2/4 (smad2, smad4) and proline hydroxylase (phd) were significantly upregulated by ELE, CGA, QC and AU supplementations. Based on the present in vitro results of grass carp, EBE, ELE, CGA, QC and AU improved the growth and lipid metabolism (except AU) in hepatocytes, and promoted the collagen deposition in intramuscular fibroblast, which is partly attributed to the signalling pathways of AKT/TOR, PPARα and TGF-β/Smads/CTGF.