Juvenile Yellow Catfish Research Articles

Shy and Bold Fish Have the Same Preference for Light Color Selection.

Personality, which matters for animal welfare, demonstrates behavioral differences. Light is one of the most important factors in aquaculture. However, how fish personality affects light color selection is unclear. In this study, we tested the personality of yellow catfish Pelteobagrus fulvidraco juveniles and then quantified the selective behaviors of different personalities under six light colors: violet (410-420 nm), yellow (580-590 nm), green (550-560 nm), red (620-630 nm), blue (470-480 nm), and white. The results showed that juveniles preferred the yellow and green light over the other colors of light, probably due to different reasons. The average cumulative dwell time in yellow (32.81 ± 5.22%), green (21.81 ± 3.58%), and red (26.36 ± 4.89%) lights was significantly longer than the other light colors, and the average visit frequency in green light (32.00 ± 4.93%) was the most. Juveniles had the longest total moved distance in green light. Moreover, the results demonstrated that shy and bold individuals had the same preference for the green light. Bold individuals could find the preferred light colors rapidly and make quick decisions for light color selection. After identifying the preferred light colors, bold individuals reduced the frequency of exploration. This study provides a theoretical basis for the welfare of juvenile yellow catfish in aquaculture.

Molecular, behavioral, and growth responses of juvenile yellow catfish (Tachysurus fulvidraco) exposed to carbamazepine

Carbamazepine (CBZ) is an anticonvulsant medication used to treat epilepsy and bipolar disorder. Due to its persistence and low removal rate in wastewater treatment plants, it is frequently detected in the environment, raising concerns regarding its potential adverse effects on aquatic organisms and ecosystems. In this study, we aimed to assess the impact of CBZ on the behavior and growth of juvenile yellow catfish Tachysurus fulvidraco, a native and economically important species in China. Fish were exposed to CBZ at three concentrations of 1, 10, or 100 µg/L for 14 days. The fish exposed to 10 and 100 μg/L of CBZ exhibited decreased feeding, and a significant increase in cannibalistic tendencies was observed in fish exposed to 100 μg/L CBZ. Acetylcholinesterase activity was increased in the brain of fish exposed to 100 μg/L CBZ. CBZ also inhibited the growth of yellow catfish. To better elucidate mechanisms of toxicity, transcriptomics was conducted in both the brain and liver. In the brain, gene networks associated with neurotransmitter dysfunction were altered by CBZ, as well as networks associated with mitochondrial dysfunction and metabolism. In the liver, gene networks associated with the immune system were altered by CBZ. The current study improves comprehension of the sub-lethal effects of CBZ and reveals novel insight into molecular and biochemical pathways disrupted by CBZ, identifying putative key events associated with reduced growth and altered behavior. This study emphasizes the necessity for improved comprehension of the effects of pharmaceutical contaminants on fish at environmentally relevant levels.

Effects of three short-chain fatty acids on growth, intestinal microbiota composition, and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

The objective of this research was to examine how the growth, ammonia tolerance, and intestinal microbiota composition of juvenile yellow catfish are affected by dietary supplementation of isobutyric acid (IBA), isovaleric acid (IVA), and 2-methylbutyric acid (2-MBA). During the 8-week trial, four groups were fed the basal diet (Control), and the basal diet supplementation with 0.25% IBA, IVA and 2-MBA, respectively. The research shows that the yellow catfish in the IBA and 2-MBA groups had a higher weight gain rate and specific growth rate than the control group, but feed conversion ratio has the opposite trend. Dietary supplementation of IBA and 2-MBA can significantly improve digestive enzymes activities (α-amylase, lipase, and trypsin) in intestinal tract and blood health (serum albumin increased, alanine transaminase and aspartate transaminase decreased). The up-regulation of IGF-1, Myod, and MyoG gene mRNA expression levels occurred significantly in the muscle tissue of the IBA, IVA, and 2-MBA groups, but IL 1 and IL8 genes in intestinal tract were significantly down-regulated. Supplementation of IBA, IVA and 2-MBA significantly increased the relative abundance of Candidatus Arthromitus, while decreased the relative abundance of Achromobacter, most notably in IBA group. After 96-h ammonia stress, cumulative mortality in IBA group was the lowest. Supplementing the diet of yellow catfish with IBA or 2-MBA can enhance their growth, digestive enzyme activity, and blood health status. Additionally, IBA can improve ammonia tolerance, which may be related to the increase abundance of Candidatus Arthromitus in intestine.

Multi-omics analysis revealed the dysfunction of ovary and testis induced by chronic hypoxia in Pelteobagrus fulvidraco

Hypoxia is a global problem that not only impairs parental fish reproductive functions and fertility but can also decrease offspring fertility through the transgenerational effect, further resulting in the degradation of fish germplasm resources in aquaculture. However, an in-depth exploration of the comprehensive mechanisms of hypoxia-induced gonadal impairment in teleosts is lacking. In this study, the juvenile yellow catfish (Pelteobagrus fulvidraco) were continuously exposed to hypoxic conditions (1.9 ± 0.3 mg/L dissolved oxygen) for one month. The transcriptome, proteome, and metabolome were integrated to study the gonadal response to hypoxia in yellow catfish comprehensively. Hypoxia altered gonadal biological processes involved in angiogenesis, energy metabolism, apoptosis, and steroidogenesis. The testes and ovaries exhibited different adaptive mechanisms in response to chronic hypoxia. Angiogenesis was activated in the testes to increase oxygen delivery. Angiogenesis was inhibited in the ovaries when ovarian hemoglobin levels increased. Activated glycolysis and catabolism of glycogenic amino acids were observed in the testes. The energy metabolism in the ovaries was disrupted by hypoxia, as reflected by disordered glycolysis and suppressed synthesis of amino acids and fatty acids. Gonadal dysfunction and suppression of germ cell development by hypoxia were observed. The decrease in synaptonemal complex protein 1 (SYCP1), SYCP3, Piwi like RNA-mediated gene silencing 2 (PIWIL2), and Nanos C2HC-type zinc finger 3 (Nanos3) in the testes reflected suppressed meiosis and spermatogenesis. The downregulation of vitellogenin 1 (VTG1), zona pellucida (ZP), growth differentiation factor 9 (GDF9), inhibin subunit beta B (Inhbb), and insulin-like growth factor (IGF) signaling inhibited folliculogenesis and vitellogenesis in the ovaries. Our results provide insight into the molecular mechanisms underlying hypoxia-induced reproductive impairment in teleosts.

Effect of density stress on the physiological, biochemical, and immunological parameters of juvenile Pelteobagrus fulvidraco during simulated transportation

Live fish transport is an important aspect of aquaculture, especially at high densities, which might cause considerable stress and compromise product quality. This study investigated the effects of transport density and time on stress responses, innate immunity, and immune gene expression in juvenile yellow catfish. The fish were designated to five density groups: D11, D12, D13, D14, and D15 (500, 333, 250, 200, and 167 kg/m3). After 36 h of transport, only the D15 group had a 100% survival rate, followed by D14 with 83% survival, and 0% in the remaining three density groups. The damage to gill filaments and the liver worsened with increasing environmental stress severity. The results showed that with the prolonged transport time, plasma cortisol (COR), and catalase (CAT), malonaldehyde (MDA) and lysozyme (LZM) levels in the livers first increased and later gradually decreased after 16 h of transport, while the activity of superoxide dismutase (SOD) continued to rise. The activities of CAT and MDA content increased as the density increased. The expression of heat shock protein (HSP) 70 and 90, tumor necrosis factor α (TNF-α), and interleukin-1β (IL-1β) in juvenile livers in D11 group was significantly higher than the control group (p < 0.05), confirming that density imposed stress on fish during transport. In conclusion, we demonstrated that increased density and time during live transport induced significant physiological stress responses in juvenile P. fulvidraco. This study provides insights into the transport of yellow catfish to improve transport measures and reduce economic losses to the aquaculture industry.

The SLC38A9–mTOR axis is involved in autophagy in the juvenile yellow catfish (Pelteobagrus fulvidraco) under ammonia stress

The primary objective of this study was to examine the effect of acute ammonia stress on hepatic physiological alterations in yellow catfish by performing a comprehensive analysis of the metabolome and transcriptome. The present study showed that ammonia stress led to liver metabolic disruption, functional incapacitation, and oxidative damage. Transcriptomic and metabolomic analyses revealed transcriptional and metabolic differences in the liver of yellow catfish under control and high ammonia stress conditions. After 96 h of acute exposure to ammonia, the mRNA levels of 596 liver genes were upregulated, whereas those of 603 genes were downregulated. Enrichment analysis of the differentially expressed genes identified multiple signalling pathways associated with autophagy, including the endocytosis, autophagy-animal, and mammalian target of rapamycin signalling pathways. A total of 186 upregulated and 117 downregulated metabolites, primarily associated with amino acid biosynthesis pathways, were identified. Multi-omics integration revealed the solute carrier family 38 member 9 (SLC38A9)-mammalian target of rapamycin axis as a signalling nexus for amino acid-mediated modulation of autophagy flux, and q-PCR was used to assess the expression of autophagy-related genes (LC3a and sqstm1), revealing an initial inhibition followed by the restoration of autophagic flux during ammonia stress. Subsequent utilisation of arginine as a specific SLC38A9 activator during ammonia stress demonstrated that augmented SLC38A9 expression hindered autophagy, exacerbated ammonia toxicity, and caused a physiological decline (total cholesterol, total triglyceride, acid phosphatase, alkaline phosphatase, aspartate aminotransferase, and alanine aminotransferase levels were significantly increased), oxidative stress, and apoptosis. Autophagy activation may be an adaptive mechanism to resist ammonia stress.

Effects of dietary sodium acetate on growth, intestinal microbiota composition, and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

Short-chain fatty acids (SCFAs), such as acetates, play a role in modifying metabolic disorders and regulating the homeostasis of the organism. In this study, the impact of dietary sodium acetate (SA) on growth, intestinal microbiota composition, and ammonia tolerance of yellow catfish. During a 56-day study, four groups of yellow catfish weighing an average of 2.72 ± 0.11 g were provided with diets containing varying proportions of SA. The diets included 0%, 0.1%, 0.2%, and 0.4% SA. Each batch consisted of three replicates, with each replicate containing 40 fish. The results indicated that dietary supplemented with 0.2% SA had significantly higher weight gain and specific growth rates than those in 0% and 0.1% groups. The feed efficiency ratio in 0% groups was significantly the highest. Dietary SA can significantly increase the activities of intestinal lipase, amylase, and pepsin, and the contents of liver total protein, immunoglobulin M, and 50% hemolytic complement, while decreasing the contents of liver triglyceride, glucose, high-density lipoprotein cholesterol, aspartate aminotransferase, alanine aminotransferase, tumor necrosis factor-α, interleukin-1, and interleukin-8, and the activities of liver superoxide dismutase, and catalase. In addition, dietary SA significantly increased the relative abundance of beneficial bacteria (Achromobacter) and production of butyrate, meanwhile decreasing the harmful bacterial (Rhodobacter) abundance. After the challenge, cumulative mortality in fish fed 0% SA diets was higher than in fish fed 0.1–0.5% SA diets after 96 h ammonia stress. Correlation analysis showed that the SA induced the enhancement of the metabolic efficiency of carbohydrates, amino acids, and lipids were also associated with the increased relative abundance of Achromobacter. In general, SA can function as a beneficial additive for enhancing growth, intestinal health, and ammonia tolerance in yellow catfish.

Preliminary Study to Assess the Impact of Dietary Rutin on Growth, Antioxidant Capacity, and Intestinal Health of Yellow Catfish, Pelteobagrus fulvidraco

This research aimed to examine the effects of dietary rutin supplementation on growth, body composition, serum biochemical indexes, liver enzyme activities and antioxidant-related genes expression, intestinal morphology, and microbiota composition of juvenile yellow catfish (Pelteobagrus fulvidraco). Rutin was added to the basal diets at doses of 0 (control), 100 mg/kg, and 500 mg/kg. Each diet was fed randomly into three tanks, each tank containing 30 fish with an initial body mass of (10.27 ± 0.62) g. The feeding trial was conducted in an indoor recirculating aquiculture system at 28 °C for 56 days. According to the findings, the inclusion of 100 mg/kg rutin significantly improved the growth performance of yellow catfish and reduced the feed conversion ratio; however, the growth promotion effect was diminished when the diet was supplemented with 500 mg/kg of rutin. The inclusion of 500 mg/kg rutin in the diet significantly reduced the level of crude lipid and protein of the whole fish. Serum activities of alkaline phosphatase, albumin, and total protein were all significantly increased when fish were fed the diet supplemented with 500 mg/kg rutin, while serum glucose was significantly lower compared to the control group. Meanwhile, dietary rutin at a concentration of 500 mg/kg significantly induced the hepatic mRNA expressions of antioxidant-related genes (including Cu/Zn-SOD, Mn-SOD, CAT, GPx) and inflammatory-associated genes (including TNFα, IL-10, LYZ). Incorporating rutin at doses of 100 mg/kg and 500 mg/kg into the diets resulted in a notable increase in superoxide dismutase (SOD) activity, while simultaneously reducing malondiadehyde (MDA) content in the liver and intestine. Intestinal villus height, villus width, muscular thickness, and lumen diameter were significantly increased with the administration of 500 mg/kg of dietary rutin. Gut microbial diversity analysis indicated that supplementing diets with 100 mg/kg and 500 mg/kg rutin significantly enhanced the abundance of Cetobacterium while decreasing Plesiomonas richness. In conclusion, dietary rutin levels at 100 mg/kg could enhance the growth, antioxidant capability, and intestinal health of yellow catfish under present experimental conditions.

Effects of ammonia and roxithromycin exposure on skin mucus microbiota composition and immune response of juvenile yellow catfish Pelteobagrus fulvidraco

As an inevitable factor in aquaculture, ammonia plays a critical role in macrolide antibiotic resistance, leading to accumulating of antibiotic-resistant bacteria in fish skin mucus. In this study, four experimental groups were implemented to test the effects of ammonia alone or in combination with roxithromycin for 28 days on skin mucus microbial composition and the immune response of yellow catfish: CON (control), AN (50.00 mg L−1 total ammonia nitrogen, TA-N), ROX (100 μg L−1 roxithromycin), and HR (50.00 mg L−1 TA-N, 100 μg L−1 ROX). This study demonstrated that ammonia or roxithromycin exposure resulted in increased plasma ammonia content and decreased total antioxidant capacity. Compared with AN group, the combined exposure of ammonia and roxithromycin inhibited the skin mucus immune response. Microbial composition analysis showed that combined exposure of ammonia and roxithromycin had no significant effect on skin mucus α-diversity as compared with CON group. The abundance of Cetobacterium, Rhizobiales_Incertae_Sedis_uncultured and Acinetobacter was increased significantly with the combined effect of ammonia and roxithromycin, these bacteria may be potentially antibiotic-resistant. As compared with CON group, the combined exposure of ammonia and roxithromycin did not affect skin goblet cell counts. This study suggests that combined exposure to ammonia and ROX increases the risk of the emergence of antibiotic-resistant bacteria.

Effects of dietary leucine on growth, antioxidant capacity, immune response, and inflammation in juvenile yellow catfish Pelteobagrus fulvidraco.

The experiment was conducted to investigate the effects of dietary leucine on growth, antioxidant capacity, immune response, and inflammation in juvenile yellow catfish. Five diets were formulated to contain five dietary leucine levels: 12.00 (control), 19.00, 26.00, 33.00, and 40.00gkg-1. Each diet was randomly assigned to triplicate groups of 30 juvenile fish (5.02 ± 0.15g) twice daily to apparent satiation for 56days. Weight gain rate, specific growth rate, and activities of liver superoxide dismutase, glutathione peroxidase, and serum lysozyme, as well as immunoglobulin M content, significantly increased with increase in dietary leucine levels up to 26.00gkg-1, but those values decreased significantly with a further increase in dietary leucine. On the contrary, the lowest malondialdehyde content was found in 26.00 and 33.00gkg-1 leucine groups. The expression levels of IGF 1 and MYF 5 genes in muscle were significantly upregulated with increase in dietary leucine levels up to 26.00gkg-1, but the expression of MSTN level showed the opposite trend. The lowest expression levels of IL 8 and TNFɑ genes in the liver were found in 26.00gkg-1 leucine groups. The quadratic regression analysis on weight gain, specific growth rate, and feed conversion ratio against dietary leucine levels indicated that the optimal dietary leucine requirement was estimated to be 26.84-27.00gkg-1of the dry diet.

Effects of dietary zinc (Zn) levels on growth performance, nutrient composition, muscle development, antioxidant and inflammatory responses in yellow catfish muscle

Three diets were formulated with dietary zinc (Zn) levels at 12.10 mg Zn/kg (L-Zn), 18.69 mg Zn/kg (M-Zn) and 120.82 mg Zn/kg (H-Zn) to explore effects of dietary Zn on growth, nutrient composition, muscle development, antioxidant and inflammatory responses in the muscle tissues of yellow catfish, one of the important economic fish in several Asian countries, including China. Zn content in M-Zn group could meet Zn requirement of yellow catfish. 270 juvenile yellow catfish (4.97 ± 0.01 g, mean ± S.E.M) were stocked in nine 300-L indoors tanks, 30 yellow catfish in each tank, and randomly provided with three diets for 10 weeks. Among three treatments, yellow catfish fed the middle Zn diets showed higher growth performance and condition factor but lower feed conversion rate than those fed the high Zn diets. Dietary Zn addition increased muscle Zn contents, but did not significantly influence feed intake, viscerosomatic and hepatosomatic index, survival, moisture, lipid, crude protein and ash contents in the muscle. Dietary Zn levels significantly influenced mRNA expression of several muscle development-related genes, such as mef2a, myod, myf5, myog, mef2d, pax7, mrf4, myhc and mstn. Middle dietary Zn levels increased antioxidant capability and reduced oxidative stress, as evaluated by enzymatic activities, gene and protein expression related to antioxidant response. Fish fed the middle Zn diets had the lower il8, tnf-α and tnf-β mRNA expression but higher il10 and tgf-β mRNA expression than those fed the high Zn diet, suggesting that optimal dietary Zn levels activated anti-inflammatory response and inhibited pro-inflammatory responses. Based on the observation, our study suggested that the suitable dietary Zn levels promoted the growth, muscle development, antioxidant and anti-inflammatory responses in fish.

Exposure to copper nanoparticles or copper sulfate dysregulated the hypothalamic-pituitary-gonadal axis, gonadal histology, and metabolites in Pelteobagrus fulvidraco

This study evaluated the effects of chronic exposure to copper nanoparticles (Cu-NPs) and waterborne copper (CuSO4) on the reproductive system of yellow catfish (Pelteobagrus fulvidraco). Juvenile yellow catfish were exposed to 100 and 200 μg Cu/L Cu-NPs and 100 μg Cu/L CuSO4 for 42 days. The results showed clear reproductive defects in both female and male yellow catfish in the 200 μg Cu/L Cu-NPs and 100 μg Cu/L CuSO4 groups. Exposure to Cu-NPs or CuSO4 inhibited folliculogenesis and vitellogenesis in the ovaries, and spermatogenesis in the testes, accompanied by elevation of the apoptotic signal. Ultrastructural observations also revealed damaged organelles of gonadal cells in both testes and ovaries. Most of the hypothalamic-pituitary-gonadal (HPG) axis genes examined and serum sex steroid hormones tended to be downregulated after Cu exposure. Metabolomic analysis suggested that gonadal estradiol level is sensitive to Cu-NPs or CuSO4. The heat map of gonadal metabolomics suggested a similar effect of 200 μg Cu/L Cu-NPs and 100 μg Cu/L CuSO4 in both the ovaries and testes. Additionally, metabolomics data showed that the reproductive toxicity due to Cu-NPs and CuSO4 may occur via different metabolic pathways. Cu-NPs tend to dysregulate the metabolic pathways of sphingolipid and linoleic acid metabolism in the ovary and the biosynthesis of amino acids and pantothenate and CoA in the testis. Overall, these findings revealed the toxicological effects of Cu-NPs and CuSO4 on the HPG axis and gonadal metabolism in yellow catfish.

Dietary N-carbamylglutamate supplementation improves ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco.

Introduction: Ammonia has been of concern for its high toxicity to animals. N-carbamylglutamate (NCG) can reduce blood ammonia levels in mammals, but studies on ammonia tolerance in fish are insufficient. Methods: Juvenile yellow catfish were fed two levels of NCG (0.00% and 0.05%) for 84days under three ammonia levels (0.00, 0.08, and 0.16mg/L NH3). Results and Discussion: The results showed that survival rate (SUR), final body weight (FBW), weight gain (WG), and serum total protein (TP), triglycerides (TG), glucose (Glu), ornithine (Orn), citrulline (Cit) contents, and liver superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), arginase (ARG), ornithine transcarbamylase (OTC) activities decreased with the increase of ammonia levels, on the contrary, feed conversion ratio (FCR), hepatosomatic index (HSI), and serum ammonia, urea, alanine aminotransferase (ALT), aspartate aminotransferase (AST), glutamine (Gln), arginine (Arg) contents, and liver malondialdehyde (MDA), tumor necrosis factor (TNF), interleukin (IL) 1, IL 8 contents, and mRNA expressions of cu/zn sod, cat, gpx, gr, tnf ɑ, il 1, and il 8 were significantly increased. Dietary 0.05% NCG supplementation had higher SUR, FBW, WG, feed intake (FI), whole-body protein, and serum TP, total cholesterol (TC), Glu, citrulline (Cit) contents, and liver SOD, GPx, argininosuccinate synthetase (ASS), argininosuccinate lyase (ASL), inducible nitric oxide synthase (iNOS) activities compared to 0.00% NCG group, but had lower serum ammonia, urea, ALT, AST, Gln, Arg contents, and liver MDA, TNF, IL 1, IL 8 contents, and neuronal nitric oxide synthase activity. At the end of bacterial challenge, cumulative mortality (CM) increased with ammonia levels increased, but serum antibody titer (AT), lysozyme (LYZ) activity, 50% hemolytic complement, immunoglobulin (Ig) contents, respiratory burst (RB), phagocytic indices decreased with ammonia levels increased. CM in 0.05% NCG group was lower than that in 0.00% NCG group, but serum AT, LYZ activity, Ig content, RB in 0.05% NCG group were significantly higher. The correlation analysis found that iNOS was positively correlated with ASS activity. This study indicates that dietary NCG supplementation can improve the ammonia tolerance of yellow catfish, and ASS may also be the target of NCG to activate the urea cycle.

Comparison of dietary arginine or/and inulin supplementation on growth, digestive ability and ammonia tolerance of juvenile yellow catfish Pelteobagrus fulvidraco

Most fish have limited use of arginine, and increasing arginine availability by adding other nutrients is an effective method. Inulin is thought to have potential synergistic effects with arginine. Four experiment groups were carried out to test the hypothesis that inulin can increase arginine availability of yellow catfish, including control, arginine, inulin and arginine mixed with inulin groups. The results showed that dietary arginine supplementation improved growth (weight gain and whole-body protein increased; IGF 1, MyoD, MyoG and Myf5 genes up-regulated), digestive ability (intestine protease and lipase increased), blood health (total protein and high-density lipoprotein cholesterol increased) and ammonia tolerance (cumulative mortality reduced; serum lysozyme, 50% hemolytic complement, respiratory burst and phagocytic indices increased) of yellow catfish, and reduced intestine inflammation (tumor necrosis factor and interleukin 1 decreased). Meanwhile, the addition of inulin to arginine-rich diets was further enhanced growth, digestive ability, intestine internal environment (butyric acid and total volatile fatty acids increased), blood health and ammonia tolerance (argininosuccinate synthetase, argininosuccinate lyase, arginase and ornithine transcarboxylase increased) of yellow catfish, and further relieved intestine inflammation. This study indicates that inulin can promote the utilization of dietary arginine; the potential synergistic effects between arginine and inulin were found in growth, digestive ability and ammonia tolerance of yellow catfish.

Effects of dietary yeast hydrolysate on the growth performance, intestine health and digestion of juvenile yellow catfish (Pelteobagrus vachelli ♂ × Pelteobagrus fulvidraco ♀)

The effects of dietary yeast hydrolysate on the growth performance, gut health, and digestion of juvenile yellow catfish were evaluated throughout a 62-day feeding trial. Isonitrogenous and isoenergetic experimental diets were prepared. The positive control fishmeal (FM) diet contained 40 % FM. The negative control plant protein diet (PM group) contained 18 % soybean meal (SBM) and 18 % rapeseed meal (RSM). In other two test diets, 1 % and 5 % of yeast hydrolysate (1 % YH and 5 % YH group) were used to replace SBM and RSM (1:1) of PM group, respectively. The results showed no significant differences in the growth performance of yellow catfish among all groups. However, daily food intake was significantly increased in 5 % YH compared with the control PM. Besides, the apparent digestibility coefficient (ADC) of dry matter improved in 1 % YH, compared with FM. And the YH groups had significantly higher total EAA concentrations in plasma than PM group. The 1 %−5 % YH supplement in plant protein diet could improve the length of gut villi and density of distal intestinal microvilli, and enhance the antioxidant capacity of mid intestine and distal intestine. Compared with PM, YH groups increased the digestive capacity of proximal intestine and mid intestine. It is concluded that 1 %−5 % of dietary yeast hydrolysate improved intestine health, food consumption and absorptive ability of yellow catfish.

Chronic toxicity study of ammonia exposure in juvenile yellow catfish Pelteobagrus fulvidraco

In aquaculture systems, long-term low ammonia stress has not received enough attention because ambient ammonia easily does not reach lethal concentrations for fish. The purpose of this study was to investigate the growth performance of yellow catfish to chronic low ammonia exposure, and to clarify the growth tolerance upper limit (GTUL) for ammonia, which can help enterprises reduce costs. We measured the 56-d survival, growth and physiological status of yellow catfish (3.96 ± 0.05 g) reared in 0.00, 1.25, 2.50, 5.00 and 10.00 mg/L total ammonia nitrogen (TAN). The survival rate was significantly reduced at ammonia level up to 10.00 mg/L TAN. However, the weight gain rate, condition factor, feed intake, hepatosomatic index, serum acid phosphatase and immunoglobulin M contents, lysozyme activity, and Bcl2 expression were significantly decreased when ammonia level exceeded 1.25 mg/L TAN, while whole-body crude protein, muscle amino acids, serum ammonia, aspartate transaminase, liver tumor necrosis factor, interleukin 1 and 8 contents, and the expressions of GPX, TNFα, IL 8, P53, AKT, PTEN were significantly increased. We recommend that juvenile yellow catfish not be exposed to ammonia concentrations >1.25 mg/L TAN (0.026 mg/L NH3) for prolonged periods of time.

Effects of dietary cellulose supplementation on the intestinal health and ammonia tolerance in juvenile yellow catfish Pelteobagrus fulvidraco

Cellulose can reduce endogenous ammonia production of non-ruminant animals by altering intestinal microbiota structure. Although the utilization of cellulose in fish is limited, we speculate that cellulose has a potential role in regulating fish ammonia tolerance. Four experiment diets with different cellulose levels (Ctrl, 4.00%, 6.00% and 8.00%) were formulated and fed to yellow catfish for 84 days. This study found that dietary supplemented with 6.00% cellulose can improve growth performance (final body weight and weight gain rate), blood health (total protein, albumin and globulin), intestinal digestive enzyme activity (protease, lipase and cellulase), and ensure intestinal structure integrity (villi length), and maintain intestinal microbiota stability (Shannon and Chao1 indexes). After 96 h ammonia stress, serum ammonia content and cumulative mortality were negative correlated with Cetobacterium abundance. The activities of ammonia metabolism enzyme (glutamine synthetase, carbamyl phosphate synthetase, argininosuccinic acid synthase and arginase) and antioxidant enzyme (superoxide dismutase, catalase and glutathione peroxidase) in 4.00% and 6.00% cellulose groups were higher than those in Ctrl and 8.00% cellulose groups. The highest mRNA expression levels of antioxidant-related genes (Cu/Zn-SOD, CAT, GPX and GR) and inflammation-related genes (IL1, IL 8 and TNFɑ) were found in 8.00% cellulose group. This study indicates dietary supplemented with cellulose can increase the Cetobacterium abundance in intestinal tract, which is closely related to ammonia tolerance of yellow catfish. The levels of 4.00–6.00% cellulose in dietary is recommended in juvenile yellow catfish.

Fish Meal Replacement by Mixed Plant Protein in the Diets for Juvenile Yellow Catfish Pelteobagrus fulvidraco: Effects on Growth Performance and Health Status.

Increasing dietary replacement levels of fish meal by alternative plant proteins are of value for aquaculture. Here, a 10-week feeding experiment was undertaken to explore the effects of fish meal replacement by mixed plant protein (at a 2 : 3 ratio of cottonseed meal to rapeseed meal) on growth performance, oxidative and inflammatory responses, and mTOR pathway of yellow catfish Pelteobagrus fulvidraco. Yellow catfish (2.38 ± 0.1 g, mean ± SEM) were randomly divided into 15 indoors fiberglass tanks, 30 fish each tank, and fed five isonitrogenous (44% crude protein) and isolipidic (9% crude fat) diets with fish meal replaced by mixed plant protein at 0% (the control), 10% (RM10), 20% (RM20), 30% (RM30), and 40% (RM40), respectively. Among five groups, fish fed the control, and RM10 diets tended to have higher growth performance, higher protein content, and lower lipid content in livers. Dietary mixed plant protein substitute increased hepatic free gossypol content and damaged liver histology and reduced the serum total essential amino acids, total nonessential amino acids, and total amino acid contents. Yellow catfish fed the control, and RM10 diets tended to have higher antioxidant capacity. Dietary mixed plant protein replacement tended to promote proinflammatory responses and inhibited mTOR pathway. Based on the second regression analysis of SGR against mixed plant protein substitutes, the optimal replacement level of fish meal by mixed plant protein was 8.7%.

The effects of dietary tributyrin on growth, intestinal health, inflammatory response and antioxidant status in juvenile yellow catfish (Pelteobagrus fulvidraco)

The effects of dietary tributyrin (TB) on growth, intestinal health, inflammatory response and antioxidant status in juvenile Pelteobagrus fulvidraco were investigated. The fish (initial weight 5.53 ± 0.02 g) were fed with diets containing 0 (control, TB0), 500 (TB1), 1000 (TB2) and 2000 (TB3) mg/kg tributyrin for 56 days. The results showed that significantly higher final weight, specific growth rate, protein efficiency ratio and protein retention were observed in fish fed with TB2 diet compared with those in TB0 (P < 0.05). Significantly higher lipid retention, whole-body fat content, intraperitoneal fat weight, intraperitoneal fat index and intestine length index were found in TB2 than that in TB3 (P < 0.05). Intestinal length, weight, villus length, muscular thickness, intestosomatic index and intestinal activities of trypsin, lipase, alkaline phosphatase, Na+/K+-ATPase in TB1 or TB2 were significantly higher than those in TB0 (P < 0.05). The fish fed with TB2 or TB3 diet had significantly lower intestinal interleukin-1β, interleukin-6, tumou necrosis factor-α, malondialdehyde contents and significantly higher hepatic glutathione, superoxide dismutase activities than those in TB0 (P < 0.05). Compared with TB0, the relative expressions of claudin-1, zomula occludens protein-1, occludin, lipoprotein lipase and fatty acid synthase were significantly increased in TB1, TB2 and TB3 (P < 0.05). Together, 1000 mg/kg TB improved growth and lipid deposition, but decreased inflammatory response, probably through modulating tight junction proteins and lipid metabolism related genes expression and activating antioxidant system.

Effects of dietary pyrroloquinoline quinone on growth performance, serum biochemical parameters, antioxidant status, and growth-related genes expressions in juvenile yellow catfish, Pelteobagrus fulvidraco

This study aimed to evaluate the impacts of dietary pyrroloquinoline quinone (PQQ) supplement on growth performance, serum biochemical parameters, antioxidant status, and growth-related genes expressions in juvenile yellow catfish, Pelteobagrus fulvidraco. Triplicate groups of fish (n = 40) with an average weight of 5 g were fed with five gradient levels PQQ-incorporated diets (0 (basal), 1.5 mg/kg; 3.0 mg/kg; 4.5 mg/kg, 6.0 mg/kg) for 56 days. Our findings revealed that fish fed with the diets containing PQQ at the level of 3.0-6.0 mg/kg showed significantly higher final body weight, weight gain rate, and specific growth rate than those of that in the control group (P &amp;lt; 0.05). The activities of protease were observed significantly increased in fish fed with diets containing 4.5 mg/kg and 6 mg/kg PQQ (P &amp;lt; 0.05). Meanwhile, fish in 4.5 mg/kg PQQ group showed significantly lower levels of serum total cholesterol, triglycerides, and low-density lipoprotein cholesterol, and significantly higher level of the high-density lipoprotein cholesterol (P &amp;lt; 0.05). The antioxidant-related parameters of superoxide dismutase and total antioxidant capacity were markedly elevated (P &amp;lt; 0.05), while malondialdehyde content was significantly reduced in 3.0-6.0 mg/kg PQQ group (P &amp;lt; 0.05). Meanwhile, the mRNA expression levels of growth-related genes (growth hormone, insulin-like growth factor 1, and insulin-like growth factor 2) were dramatically up-regulated in the liver of fish fed with the diets containing 3-6 mg/kg PQQ in comparison with the control group (P &amp;lt; 0.05). In conclusion, dietary PQQ could improve the growth performance, serum biochemical parameters, antioxidant status, and growth-related genes expressions in juvenile yellow catfish, and the optimal dietary PQQ level was evaluated to be 4.92 mg/kg of dry diet for juvenile yellow catfish.