Growth performance, physiological parameters, and transcript levels of lipid metabolism-related genes in hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂) fed diets containing Siberian ginseng.

In high-density aquaculture, fish health can suffer because of excessive feeding, which causes fatty liver disease. Siberian ginseng (Acanthopanax senticosus) has been used as a feed additive to promote animal growth, immunity, and lipid metabolism. In this study, we explored the effects of A. senticosus on the physiology of hybrid yellow catfish (Tachysurus fulvidraco ♀ × Pseudobagrus vachellii ♂). A control group and five groups fed diets containing A. senticosus (0.5, 1, 2, 4, and 8 g A. senticosus/kg feed) were established and maintained for 8 weeks. Dietary supplementation with A. senticosus at 4 g/kg promoted growth of the hybrid yellow catfish. Serum total cholesterol (TC) and triacylglycerol (TG) levels at 2 g/kg A. senticosus (TC: 1.31 mmol/L; TG: 1.08 mmol/L) were significantly lower than in the control group (TC: 1.51 mmol/L; TG: 1.41 mmol/L), and 4 g/kg A. senticosus (17.20 µmol/g tissue) reduced the liver TG level compared with the control group (21.36 µmol/g tissue) (P <0.05). Comparative transcriptomic analysis of liver tissue between the control group and the group showing optimum growth (4 g/kg A. senticosus) revealed 820 differentially expressed genes and 44 significantly enriched pathways, especially lipid metabolism pathways such as unsaturated fatty acid and fatty acid metabolism. The transcript levels of five lipid metabolism-related genes were determined by quantitative real-time PCR. The results showed that 2-4 g/kg A. senticosus supplementation reduced the FADS2, ELOVL2, CYP24a, and PLPP3 transcript levels and 4 g/kg A. senticosus increased the DIO2 transcript level (P <0.05), leading to altered synthesis of TG and thyroxine and reduced fat deposition in the liver. Our results show that dietary A. senticosus affects the regulation of fat metabolism and promotes the growth of hybrid yellow catfish. A. senticosus is a healthy feed additive, and the appropriate dietary supplementation rate is 2-4 g/kg.

Isoleucine improved growth performance, and intestinal immunological and physical barrier function of hybrid catfish Pelteobagrus vachelli × Leiocassis longirostris.

This study was performed to determine effects of dietary isoleucine (Ile) on growth performance, and intestinal immunological and physical barrier function of hybrid catfish Pelteobagrus vachelli × Leiocassis longirostris. Six hundred and thirty fish (33.11 ± 0.09 g) were randomly divided into seven experimental groups with three replicates each, and respectively fed seven diets with 5.0, 7.5, 10.0, 12.5, 15.0, 17.5, and 20.0 g Ile kg-1 diets for 8 weeks. The results showed improvement of growth performance, feed intake, feed utilization, relative gut length (RGL), and intestinal fold height and width by dietary Ile (P < 0.05). Meanwhile, dietary Ile (12.5 g kg-1 diet) improved the activities of lysozyme (LZM), acid phosphatase, alkaline phosphatase and the contents of complement 3 (C3), C4, and immunoglobulin M (IgM) (P < 0.05). The c-type-lectin, c-LZM, g-LZM, and hepcidin mRNA expressions in the intestine were up-regulated in fish fed diets with 10.0-20.0 g Ile kg-1 diet (P < 0.05). Dietary Ile (10.0-12.5 g Ile kg-1 diet) increased intestinal ß-defensin mRNA expression partially in association with Sirt1/ERK/90RSK signaling pathway. Dietary Ile (12.5-15.0 g Ile kg-1 diet) decreased oxidative damage and improved antioxidant ability by increasing activities and expressions of superoxide dismutase, glutathione peroxidase, and glutathione reductase, glutathione-S-transferase (P < 0.05). The occludin, ZO-1, ZO-2, claudin3, and claudin 7 mRNA expressions in the intestine were up-regulated in fish fed diets with 10.0 and 12.5 g Ile kg-1 diet (P < 0.05), whereas the myosin light chain kinase gene expression was decreased in fish fed diets with 7.5-17.5 g Ile kg-1 diet. Dietary Ile (10-12.5 g Ile kg-1 diet) decreased apoptotic responses by reducing the expression of caspase3 and caspase 9 via the AKT/TOR signaling pathway. Based on the quadratic regression analysis of PWG, the dietary Ile requirement of hybrid catfish was estimated to be 12.43 g Ile kg-1 diet, corresponding to 32.05 g Ile kg-1 dietary protein. Collectively, dietary Ile improved growth performance and immunological and physical barrier function of intestine in hybrid catfish.

The protective effects of selenium on chronic ammonia toxicity in yellow catfish (Pelteobagrus fulvidraco).

Ammonia is toxic to most fish, and its negative effects can be eliminated by nutritional manipulation. In this study, triplicate groups of yellow catfish (0.58 ± 0.03 g) were fed diets supplemented with 0, 0.30 and 0.60 mg selenium (Se) kg-1 diet for 56 days under three ammonia contents (0.00, 5.70 and 11.40 mg L-1 total ammonia nitrogen). The results showed that ammonia toxicity could affects growth (weight gain, feed efficiency ratio, Se contents in muscle and whole body declined) and survival, leads to oxidative stress (total antioxidant capacity, superoxide dismutase, catalase and glutathione peroxidase activities declined and malondialdehyde accumulation), immunosuppression (lysozyme activity, 50% hemolytic complement, immunoglobulin M, respiratory burst and phagocytic index declined) and cytokines release (TNF, IL 1 and IL 8 elevated), induces up-regulation of antioxidant enzymes (Cu/Zn-SOD, Mn-SOD, CAT and GPx), cytokines (TNFα, IL 1 and IL 8) and pro-apoptotic genes (p53, Bax, Cytochrome c, Caspase 3 and Caspase 9) transcription, and down-regulation of anti-apoptotic gene Bcl2 transcription. The dietary Se supplementation could mitigate the adverse effect of ammonia poisoning on fish growth, oxidative damage, immunosuppression and apoptotic.

Protective effects of diet containing rutin against trichlorfon-induced muscle bioenergetics disruption and impairment on fatty acid profile of silver catfish Rhamdia quelen.

Trichlorfon is an organophosphate insecticide that is widely used on fish farms to control parasitic infections. It has been detected in freshwater ecosystems as well as in fishery products. There is a growing body of evidence to suggest that certain feed additives may reduce or prevent pesticide-induced toxicity in fish. The aim of the present study was to determine whether acute exposure to trichlorfon would alter bioenergetic homeostasis and alter fatty acid profiles in muscles of silver catfish (Rhamdia quelen). We also sought to determine whether rutin prevents or reduces these effects. Cytosolic and mitochondrial creatine kinase (CK) and activities of complexes II-III and IV in muscle were significantly inhibited by exposure to 11 mg/L trichlorfon for 48 h compared to effects in the unexposed group. Total content of polyunsaturated fatty acids (omega-3 and omega-6) were significantly lower in muscle of silver catfish exposed to 11 mg/L trichlorfon for 48 h than in the unexposed group. Addition of 3 mg rutin/kg feed increased CK activity and prevented inhibition of complex IV activity, as well as preventing all alterations of muscle fatty acid profiles elicited by exposure to trichlorfon. No significant differences were observed between groups with respect to muscle adenylate kinase or pyruvate kinase activities, as well as total content of saturated and monounsaturated fatty acids. Our findings suggest that exposure (48 h) to 11 mg trichlorfon/L water inhibits cytosolic and mitochondrial CK activity in muscle. Trichlorfon also affects activities of complexes II-III and IV in respiratory chain, with important consequences for adenosine triphosphate production. The pesticide alters fatty acid profiles in the fish and endangers human consumers of the product. The most important finding of the present study is that inclusion of rutin improves bioenergetic homeostasis and muscle fatty acid profiles, suggesting that it reduces trichlorfon-induced muscle damage.

Single or Combined Dietary Supply of Psidium guajava and Phyllanthus amarus Extracts Differentially Modulate Immune Responses and Liver Proteome in Striped Catfish (Pangasianodon hyphophthalmus).

Guava Psidium guajava L (Pg) and bhumi amla Phyllanthus amarus Schum. et Thonn (Pa) are well-known plants in traditional medicine. However, the capacity of these plants for improving the immune system of aquatic species has received less attention so far. This study aimed to investigate the effects of single supply or mixture of Pg and Pa extracts on immune responses, disease resistance and liver proteome profiles in striped catfish Pangasianodon hypophthalmus. Fish were fed diets including basal diet 0% or one of three doses of each plant extract, either alone or in mixture, 0.08, 0.2, or 0.5% Pg, Pa or mixture (Pg:Pa, v/v) for 6 weeks. The immune parameters (respiratory burst activity (RBA); nitric oxide synthase (NOS), total immunoglobulin, lysozyme, and complement activities) were examined at W3, W6 post-feeding, and after challenge test. The growth parameters and the challenge test with Edwardsiella ictaluri were done at W6. The liver proteome profiles were analyzed in W6 at 0.08 and 0.5% of each extract. The results showed that extract-based diets significantly improved growth parameters in the Pg0.2 group compared to control. The cellular immune responses in spleen and the humoral immune responses in plasma were significantly improved in a dose and time-dependent manner. Diets supplemented with single Pg and Pa extracts, and to lesser extent to combined extracts, could significantly decrease the mortality of striped catfish following bacterial infection compared to control. The proteomic results indicated that some pathways related to immune responses, antioxidant and lipid metabolism were enriched in liver at W6. Several proteins (i.e., CD8B, HSP90AA1, HSP90AB1, PDIA3, CASP8, TUBA1C, CCKAR, GNAS, GRIN2D, PLCG1, PRKCA, SLC25A5, VDAC2, ACTN4, GNAI2, LCK, CARD9, NLRP12, and NLRP3) were synergistically upregulated in mixture of Pg and Pa-based diets compared to control and single dietary treatments. Taken together, the results revealed that single Pg and Pa extracts at 0.2 and 0.5% and their mixture at 0.08 and 0.5% have the potential to modulate the immune mechanisms and disease resistance of striped catfish. Moreover, the combination of Pg and Pa in diets suggested positive synergistic effects liver proteome profile related to immune system processes.

Dietary taurine incorporation to high plant protein-based diets improved growth, biochemical, immunity, and antioxidants biomarkers of African catfish, Clarias gariepinus (B.).

Plant protein (PP) sources are generally used in high levels in fish diets. Mostly, PP sources are deficient in taurine; hence, there is a need for its supplementation to fish fed high PP diets. Therefore, effects of dietary taurine were examined on growth performance, feed utilization, immunity, and antioxidant parameters of African catfish, Clarias gariepinus (B.). Fish (10.3 ± 0.4 g) were fed on diets (40% crude protein) containing different taurine levels of 0 (control), 10, 20, 30, or 40 g/kg diet for 12 weeks. Fish fed a taurine-free diet (the control) with high PP sources showed poor growth as compared with these fed taurine-enriched diets where taurine stimulatory effects were observed on fish growth and feed intake. Feed conversion ratio and fish survival rate were not significantly differed among different treatments. Fish fed taurine-enriched diets showed also higher levels of serum glucose, cholesterol, total protein, albumin, globulin, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, urea, and creatinine over that fed the control diet. Furthermore, lysozyme and respiratory burst activities as well as superoxide dismutase and catalase activities were significantly elevated in fish fed taurine-enriched diets (P < 0.05) and their highest levels were observed in fish fed 30 g/kg diet. Additionally, taurine deposition in fish muscles was positively correlated with dietary taurine levels (P < 0.05). The present study concludes that taurine is a limiting factor for growth, immunity, and antioxidants responses of African catfish fed high PP-based diets and it should be incorporated in its diets with an optimum level of 20 g/kg diet.

Effect of dietary threonine on growth performance and muscle growth, protein synthesis and antioxidant-related signalling pathways of hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂.

The experiment was conducted to investigate the effects of dietary threonine (Thr) on growth performance and muscle growth, protein synthesis and antioxidant-related signalling pathways of hybrid catfish Pelteobagrus vachelli♀ × Leiocassis longirostris♂. A total of 1200 fish (14·19 (se 0·13) g) were randomly distributed into six groups with four replicates each, fed six diets with graded level of Thr (9·5, 11·5, 13·5, 15·4, 17·4 and 19·3 g/kg diets) for 56 d. Results showed (P < 0·05) that dietary Thr (1) increased percentage weight gain, specific growth rate, feed efficiency and protein efficiency ratio; (2) up-regulated growth hormone (GH), insulin-like growth factor 1 (IGF-1), proliferating cell nuclear antigen, myogenic regulation factors (MyoD, Myf5, MyoG and Mrf4) and myosin heavy chain (MyHC) mRNA levels; (3) increased muscle protein content via regulating the protein kinase B/target of rapamycin signalling pathway and (4) decreased malondialdehyde and protein carbonyl contents, increased catalase, glutathione-S-transferase, glutathione reductase and GSH activities, up-regulated mRNA levels of antioxidant enzymes related to NFE2-related factor 2 and γ-glutamylcysteine ligase catalytic subunit. These results suggest that Thr has a potential role to improve muscle growth and protein synthesis, which might be due to the regulation of GH-IGF system, muscle growth-related gene, antioxidative capacity and protein synthesis-related signalling pathways. Based on the quadratic regression analysis of specific growth rate, the Thr requirement of hybrid catfish (14·19-25·77 g) was estimated to be 13·77 g/kg of the diet (33·40 g/kg of dietary protein).

Effect of zinc on growth performance and cellular metabolic stress of fish exposed to multiple stresses.

Global warming due to increasing temperature and contamination in aquatic environment has been found to be inducing cellular metabolic stress in fish. The present study focused on temperature and contamination in aquatic ecosystems and its alleviation/mitigation. Hence, this study was conducted to evaluate the role of zinc to improve growth performance, cellular metabolic stress, and digestive enzymes of the Pangasianodon hypophthalmus reared under lead (Pb) and high temperature. Two hundred and seventy-three fishes were distributed randomly into seven treatments, each with three replicates. Three isocaloric and isonitrogenous diets with graded levels of zinc at 0 mg/kg, 10 mg/kg, and 20 mg/kg were prepared. The Pb in treated water was maintained at the level of 1/21th of LC50 (4 ppm) and maintained at a temperature of 34 °C in exposure groups. The growth performance in terms of weight gain (%), protein efficiency ratio (PER), and specific growth rate (SGR) was found to be inhibited, and the feed conversion ratio (FCR) was enhanced in the Pb and high temperature-exposed group, whereas zinc supplementation has improved weight gain (%), FCR, PER, and SGR. The liver, gill, muscle, and kidney tissues of carbohydrate metabolic enzymes (LDH and MDH), protein metabolic enzymes (ALT and AST), and liver, gill, and muscle G6PDH and ATPase as well as intestinal digestives enzymes (proteases, amylase, and lipase) and intestinal ALP were significantly affected (p < 0.01) by Pb and high temperature exposure to P. hypophthalmus. We herein report the role of zinc in mitigating cellular metabolic stress in fish exposed to Pb and high temperature.

Dietary Glycyrrhiza uralensis extracts supplementation elevated growth performance, immune responses and disease resistance against Flavobacterium columnare in yellow catfish (Pelteobagrus fulvidraco).

The present study was conducted to evaluate the influence of Glycyrrhiza uralensis (G. uralensis) extracts on the growth performance, histological structure, immune response and disease resistance against Flavobacterium columnare (F. columnare) of yellow catfish. Fish were fed with two different diets, i.e., basal diet as control group (CG) and diet containing G. uralensis extracts as experimental group (GG). After 60 days feeding, growth performance of GG fish was significantly improved, with increased WG and SGR but decreased FCR compared to CG fish. Fish were then challenged with F. columnare for two times, as fish showed rare mortality after the first infection. GG fish showed significantly lower cumulative mortality during F. cloumnare infection than CG fish after 21 days infection (dpi). Epithelial cell exfoliation and obvious cellular vacuolization in the skin and congestion of gill lamellae were detected in CG fish, while GG fish showed increased width of epidermis and mucous cells number in skin, and increased length of secondary lamina in gill. GG fish also exhibited higher enzyme activity of lysozyme in serum and mRNA expression of lysozyme in head kidney than CG fish at most time points post infection. G. uralensis extracts supplementation also induced earlier serum anti-oxidative responses, with increased superoxide dismutase activity and total antioxidant capacity in GG fish at 1 dpi. Compared to CG fish, GG fish showed increased expression level of genes involved in TLRs-NFκB signaling (TLR2, TLR3, TLR5, TLR9, Myd88, and p65NFκB), resulting in higher expression levels of pro-inflammatory cytokines (IL-1ß and IL-8) in the head kidney post infection. However, these genes showed deviation in the gill of GG fish, which increased at some time points but decreased at other time points. Moreover, G. uralensis extracts supplementation also significantly unregulated the expression levels of IgM and IgD in head kidney, and the expression levels of IgM in the gill of yellow catfish, suggesting the elevated humoral immune response during F. columnare infection. All these results contributed to the elevated disease resistance ability against F. cloumnare infection of yellow catfish after dietary G. uralensis extracts supplementation.

Growth, body composition, mineralisation and Na+/K+-ATPase activity of fingerling Heteropneustes fossilis (Bloch) fed diets with different levels of potassium.

A growth trial was performed to optimise the inclusion of potassium (K) in feeds of Heteropneustes fossilis (body weight [BW] 6.92 ± 0.1 g). Eight isonitrogenous and isoenergetic diets with varying dietary K levels were prepared by supplementing 0, 1.91, 3.82, 5.73, 7.64, 9.55, 11.46 and 13.37 g KCl/kg basal diet. Analysed dietary K levels were 0.16, 1.12, 2.08, 3.19, 4.18, 5.16, 6.11, 7.14 and 8.16 g/kg dry matter. BW gain, feed conversion ratio (FCR), protein gain (PG) and gill Na+/K+-ATPase activity were best in fish fed 4.18 g K/kg diet. The K concentrations in the whole body and vertebrae increased linearly with the increase up to 5.16 g K/kg diet and reached then a plateau. The K-retention [%] was highest in fish fed the basal diet and decreased with the further inclusion of dietary K up to 2.08 g/kg followed by no change up to diet containing 4.18 g K/kg and then declined further in fish fed higher levels of dietary K. Serum alkaline phosphatase activity was found to increase up to 4.18 g K/kg diet. Regression of BW gain, PG, gill Na+/K+-ATPase and vertebrae K concentration against varying levels of dietary K using broken-line model indicated that an inclusion of 5.44 g K/kg diet is the optimum for maximising growth and mineralisation of H. fossilis.

Study the immunomodulation of anthracenedione in striped dwarf catfish, Mystus vittatus against pathogenic bacteria, Aeromonas hydrophila.

Anthracenedione is a derivative of anthraquinone aromatic organic natural pigments found in senna, aloe latex, rhubarb, cascara, lichens, and fungi having broad range of bioactivity, including anti-cancer, anti-inflammatory, anti-microbial, anti-fungal, anti-oxidant, anti-viral activities suggesting potential for clinical purpose of many diseases. The effect of anthracenedione enriched diet on growth, hematology, innate and adaptive immune parameters as well as protection from Aeromonas hydrophila in Mystus vittatus was reported. The weight gain, feed intake, specific growth rate (SGR), and feed conversion ratio (FCR) were significantly increased in uninfected groups fed with 5 mg kg-1 diet. The red blood cells (RBC) and white blood cells (WBC) count and the percentage of lymphocytes were significantly augmented in both infected and uninfected groups feeding with any diet. The percentage of monocytes, eosinophils, neutrophils and the biochemical profile such as total protein, albumin, and globulin also were significantly increased in the infected and uninfected groups fed with 5 mg kg-1 enriched diet. The innate and adaptive immune parameters such as phagocytic activity, immunoglobulin M (IgM), respiratory burst activity, complement activity, and lysozyme activity were significantly increased in uninfected and infected groups fed with 5 or 10 mg kg-1 diets but not with 1 mg kg-1 diet. The serum superoxide dismutase (SOD) activity is significantly increased in the uninfected and infected fish fed with 5 mg kg-1 diet but the increase was not significantly observed in 1 or 10 mg kg-1 diets. The nitric oxide (NO) production is significantly elevated in both uninfected and infected groups fed with 5 mg kg-1 diet. On the other hand, the lymphocyte proliferation and myeloperoxidase (MPO) activity were significantly increased the infected and uninfected groups fed with 5 and 10 mg kg-1 diets. The cumulative mortality was found 5% with 1 and 5 mg kg-1 diet groups while it was observed 10% mortality with 10 mg kg-1 diet group. Based on the results, it is observed that feeding the uninfected and infected groups with 5 mg kg-1 anthracenedione diet resulted in better improvement of growth, hematological, biochemical, and innate as well as adaptive immune parameters in M. vittatus against A. hydrophila.

Quantification of dietary calcium requirement of fingerling Heteropneustes fossilis based on growth, feed conversion efficiency, mineralization and serum alkaline phosphatase activity.

Seven isonitrogenous (400 g/kg crude protein) and isocaloric (17.89 kJ/g gross energy) purified diets (casein-gelatin based) with different concentrations of calcium (0, 1, 2, 3, 4, 5 and 6 g/kg) supplemented with calcium lactate at the levels of 0, 5.4, 10.8, 16.3, 21.8, 27.27 and 32.73 g/kg were prepared and fed for 12 weeks to triplicate groups of Heteropneustes fossilis (7.46 ± 0.03 g) to determine the optimum dietary calcium requirement. Analysed values of calcium in the diets were 2.41, 3.82, 4.56, 5.99, 6.71, 7.40 and 8.19 g/kg, respectively. Absolute weight gain, specific growth rate, protein retention efficiency, protein gain and feed conversion ratio of fish fed diets with increasing levels of dietary calcium improved up to 5.99 g/kg and then levelled off. Whole-body protein, moisture and ash contents improved up to 5.99 g/kg dietary calcium and stabilized thereafter. However, whole-body fat exhibited reverse pattern and decreased with incremental levels of dietary calcium up to 5.99 g/kg. Whole-body and vertebrae mineralization was also significantly affected (p < .05) by the increasing dietary calcium levels. Alkaline phosphatase activity improved significantly (p < .05) up to 6.71 g/kg, and no change was recorded beyond this level. Serum calcium and phosphorus concentrations were not influenced (p > .05) by dietary calcium levels. The Ca-P ratio remained static in the whole body, vertebrae and serum. Broken-line regression analysis of data obtained on growth, mineralization and serum ALP activity against increasing levels of dietary calcium reflected the optimum calcium requirement between 5.77-6.81 g/kg diet.

Comparative Transcriptome Analysis Reveals Differentially Expressed Genes and Signaling Pathways Between Male and Female Red-Tail Catfish (Mystus wyckioides).

Sexual dimorphism is widespread in fish species. The red-tail catfish (Mystus wyckioides) is a commercially important catfish in the lower reaches of the Lancang River and the Mekong basin, and it shows a growth advantage in males. Here, RNA-seq was for the first time used to explore the gene expression difference between the sexes in the hypothalamus and pituitary of red-tail catfish, respectively. In the hypothalamus, 5732 and 271 unigenes have significantly higher and lower expressions, respectively, in males compared with females. KEGG analysis showed that 212 DEGs were annotated to 216 signaling pathways, and enrichment analysis suggested different levels of cAMP and glutamatergic synapse signaling between male and female hypothalami and some of the DEGs appear involved in gonad development and growth. In the pituitary, we found only 19 differentially expressed unigenes, which were annotated to 32 signaling pathways, most of which play important roles in gonad development.

Tropical Vegetable Oils Do Not Alter Growth Performance in African Catfish through a High n-6 Polyunsaturated Fatty Acids Biosynthesis Capacity.

The main objective of this study was to determine the best vegetable oils (VO) for nutrition of African catfish by assessing the effects of a complete replacement of fish oil (FO) by different VO sources on its growth performance, fatty acid composition, and elongase-desaturase gene expression levels. Fish (16.2 g of initial body weight) were fed with five experimental isonitrogenous, isolipidic, and isoenergetic diets in which FO was totally replaced by cottonseed oil (CO), palm oil (PO), desert date oil (DO), or Shea butter (SB). Complete replacement of FO with VO did not affect growth performance except for low values in fish fed SB diet. Muscle n-3 LC-polyunsaturated fatty acids (PUFA) were significantly reduced in fish fed VO-based diets when compared with FO fed fish. However, the muscle arachidinic acid (ARA) levels in phospholipid class were 1.4 to 1.6 times higher in fish fed CO and DO diets than FO fed fish despite the lower ARA suppliers from these VO-based diets, suggesting endogenous LC-PUFA biosynthesis from PUFA precursors in fish fed these VO. The fads2 and elovl5 gene expression levels in liver of fish fed DO were also higher compared to FO controls. Therefore, all the results support the hypothesis that African catfish has higher biosynthesis capacity to convert vegetable n-6 PUFA precursors like linoleic acid (LNA, 18:2n-6) into n-6 LC-PUFA of the ARA type, compared to the conversion of vegetable α-linolenic acid (ALA, 18:3n-3) into n-3 LC-PUFA of the eicosapentanoic acid (EPA) or docosahexanoic acid (DHA) type. The results also indicate that DO can be recommended as the best alternative to FO replacement in African catfish nutrition.

Effects of Microencapsulated Saccharomyces cerevisiae on Growth, Hematological Indices, Blood Chemical, and Immune Parameters and Intestinal Morphology in Striped Catfish, Pangasianodon hypophthalmus.

This study investigated the effects of dietary probiotic Saccharomyces cerevisiae in the striped catfish, Pangasianodon hypophthalmus, which is an important aquaculture species. Freeze-dried microencapsulated probiotic S. cerevisiae with guar gum was performed and used for fish feed supplementation. Striped catfish were fed for 120 days with one of three experimental diets: basal diet (control), basal diet supplemented with 106-CFU S. cerevisiae g-1 diet (S. cerevisiae 106), and basal diet supplemented with 108-CFU S. cerevisiae g-1 diet (S. cerevisiae 108). The S. cerevisiae-supplemented diets significantly improved growth performance including growth rate and feed conversion ratio over 120 days of culture period (P < 0.05). The rate of survival was similar in all experimental groups. Supplementation with S. cerevisiae did not significantly affect whole body proximate composition (P > 0.05). In addition, probiotic S. cerevisiae had no effects on hematological indices and blood chemistry values (glucose, cholesterol, triglycerides, protein, albumin, blood urea nitrogen, chloride, calcium, magnesium, iron, and phosphorus) (P > 0.05). However, dietary S. cerevisiae led to increases in humoral immune parameters including total immunoglobulin, lysozyme, and alternative complement activities (P < 0.05). Dietary S. cerevisiae led to increase intestinal villus height in the anterior part of intestine (P < 0.05). Taken together, while the dietary S. cerevisiae had no detectable effects on hematological indices and several metabolic indicators, significant beneficial probiotic effects were observed on rates of growth, feed conversion ratio, and immune parameters.

Effect of dietary alanyl-glutamine dipeptide against chronic ammonia stress induced hyperammonemia in the juvenile yellow catfish (Pelteobagrus fulvidraco).

Triplicate groups of juvenile yellow catfish (1.98 ±â€¯0.01 g) were fed diets supplemented with 0% and 1% alanyl-glutamine dipeptide (AGD) for 56 days under three ammonia concentrations (0.01, 5.70 and 11.40 mg L-1 total ammonia nitrogen). The results showed that ammonia poisoning could induce growth (weight gain and specific growth rate) and survival reduction, live ammonia and serum malondialdehyde accumulation, and subsequently lead to blood deterioration (serum total protein, albumin, globulin, alkaline phosphatase and acid phosphatase reduced), oxidative stress (superoxide dismutase and glutathione peroxidase activities declined), and induce down-regulation of antioxidant enzymes (SOD, GPX and GRX) genes transcription. However, dietary supplemented with 1% AGD could mitigate the adverse effect of ammonia poisoning on fish growth performance.

Comparative study of three predominant gut Bacillus strains and a commercial B. amyloliquefaciens as probiotics on the performance of Clarias gariepinus.

The present study was conducted to evaluate the supplementation of three autochthonous Bacillus strains (B. subtilis, B. amyloliquefaciens and B. cereus) and a commercial B. amyloliquefaciensin doses of 1 × 1010 CFU/kg on the growth performance, hematology, antioxidant activities, digestive enzyme levels, immune status and disease resistance of Clarias gariepinus. A total of 300 fish (75.23 ±â€¯1.6 g) were randomly divided into 5 groups (each group was subdivided into 2 subgroups, 30 fish/each). The control group was fed basal diet (D0). Diets D1, D2, D3 and D4were supplemented with B. subtilis, B. amyloliquefaciens, B. cereus and a commercial B. amyloliquefaciens, respectively. During the course of the experiment, D3 showed the best body weight, weight gain, specific growth rate and food conversion ratio. The measured hemogram blood parameters had the highest significant increase in D3. WBCs and monocyte counts had no significant differences among the experimental groups. The serum antioxidant and digestive enzymes were the highest in D3 and were the lowest in D0. After 15 d, the non-specific immune parameters were markedly increased in fish fed probiotic-containing diet compared with the control. After 30 d, the highest significant immune parameters were observed in D3; D1 and D2 had no significant differences in serum lysozyme activity, nitric oxide and IgM compared with D0. Myostatin cDNA levels were adversely affected by probiotic supplements compare with the control. The PACAP expression showed the highest significant value in D3 followed by D1and D4then D2. The relative survival percentages of the Aeromonas sobria challenged C. gariepinus were the highest in D3, D2, D4 and then D1. Among the three isolated Bacillus species, dietary supplementation with the B. cereus had the highest performance in C. gariepinus compared with the commercial B. amyloliquefaciens and the control group.

Protective effect of apple mangrove Sonneratia caseolaris extract in Edwardsiella tarda-infected African catfish, Clarias gariepinus.

Outbreaks of edwardsiellosis have severe impact on the aquaculture production of African catfish Clarias gariepinus. In this study, feed supplemented with apple mangrove Sonneratia caseolaris extract was evaluated for its protective effect against Edwardsiella tarda infection in African catfish. Results showed an increase in growth performance and higher survival rate in the treatment groups in a dose dependent manner. Haematological analyses showed an increase in white blood cell count in the treatment groups. Histopathological analysis revealed degenerative changes and regeneration of liver tissue architecture in both the control and treatment groups. However, the presence of inflammatory cells was found exclusively in the kidney of T3 treatment group that was supplemented with the highest dose of extract at 3.17 mg/ml, which inferred the activation of immune response in the fish. Contrast to the deteriorative alteration observed in the kidney of the control group due to E. tarda infection, treatment group exhibited tissue regeneration and well-defined kidney tissue architecture at 3 dpi. Taken together, these results demonstrated that supplementation with the methanol extract of S. caseolaris possesses protective effect in African catfish against the infection of E. tarda.

Growth, physiological, antioxidants, and immune response of African catfish, Clarias gariepinus (B.), to dietary clove basil, Ocimum gratissimum, leaf extract and its susceptibility to Listeria monocytogenes infection.

Clove basil, Ocimum gratissimum, is a native plant to Africa and grows virtually in tropical and subtropical regions. It has good aroma and its leaves have become used as a spicy and in traditional medicine. The use of plant leaves in fish diets may deteriorate their growth because it may content anti-nutritional factors. Thus, it is better to use plants leaves extract. In the current study, clove basil leaves extract (CBLE) was administrated to African catfish, Clarias gariepinus (B.) to evaluate its effect on growth performance, physiological, antioxidants, and innate immunity variables. Fish (10.7 ±â€¯0.5 g) were fed on diets enriched with 0.0, 5, 10, or 15 g CBLE/kg diet for 12 weeks. After the feeding trial, fish were further exposed to pathogenic bacteria (Listeria monocytogenes) for 14 days. Fish performance and feed intake were significantly enhanced with increasing CBLE levels and its optimum level is found to be 12 g/kg diet. It is noticed that the dietary CBLE in African catfish diets increased significantly the intestinal villi length, villi width, and absorption area in a dose-dependent manner and fish weight was highly correlated with villi length, villi width, and absorption area (R2 = 0.91, 0.91, and 0.92, respectively). On the other side, Dietary CBLE has significant modulatory effect on hemato- and physiological variables of African catfish in a dose-dependent manner. In this regard, blood glucose and cholesterol levels decreased significantly; mean while total protein, albumin, and globulin increased significantly in fish fed high CBLE levels (10-15 g/kg diet). Furthermore, activities of aspartate aminotransferase and alanine aminotransferase, alkaline phosphatase, urea, and creatinine levels were significantly elevated with increasing dietary CBLE levels and their maximum values were detected in fish fed 15 g CBLE/kg diet. Antioxidants and immunity variables were significantly enhanced by CBLE supplementation. Additionally, fish mortality after bacterial challenge was highest in fish fed the control diet (85%) than those fed CBLE-enriched diets. The lowest fish mortality was observed in fish fed 15 g CBLE/kg diet (13.5%). This study evoked that CBLE administration enhanced the performance, feed utilization, antioxidant, and innate immunity properties of African catfish with optimum level of 12 g/kg diet. Also, its supplementation enhanced fish challenge against L. monocytogenes.

Bentonite clay supplemented diet on immunity in stinging catfish, Heteropneustes fossilis against Aeromonas hydrophila.

The effect of Sodium Bentonite (SB) enriched diet on growth performance, innate immune response, and disease resistance in stinging catfish, Heteropneustes fossilis against Aeromonas hydrophila is reported. The infected fish fed with 5% SB had the maximum weight gain diet (PWG %) and specific growth rate (SGR %) were 26% and 29% when compared to 14% and 17% with 10% diet. Similarly the phagocytic activity increased significantly when infected fish were fed with 5% or 10% SB diets during the experimental period; the complement, respiratory burst and lysozyme activities were also significantly enhanced on weeks 2 and 4. The lower cumulative mortality (10% and 15%) was observed when the infected fish were fed with 5% and 10% SB diets for 30 days. The results suggest that the infected H. fossilis after administration of 5% and 10% SB enriched diets for 30 days had significantly improved growth performance, innate immunity, and disease resistance against A. hydrophilla. Hence, sodium bentonite can be used as a feed additive to stimulate immunity and for disease resistance in the effective production of economically valuable freshwater catfish, H. fossilis.