Search

An 8-week feeding trial was conducted to evaluate the effects of dietary γ-aminobutyric acid (GABA) on growth performance, immune response, and disease resistance for juvenile whiteleg shrimp, Litopenaeus vannamei. Five isonitrogenous diets were formulated by supplementing 0 (CON), 50 (GABA50), 100 (GABA100), and 300 (GABA300) mg of GABA and 4 g of oxytetracycline (OTC) per kilogram of diet. A total of 225 juvenile whiteleg shrimp with an initial weight of 2.97 ± 0.06 g were randomly distributed and reared in 15 aquaria as triplicates. After 8 weeks of the feeding trial, weight gain, specific growth rate, feed efficiency, and protein efficiency ratio of shrimp fed GABA100 were significantly higher than those of shrimp fed CON, GABA50, and GABA300 diets ( P < 0.05 ). However, there were no significant differences among shrimp fed CON, GABA50, GABA300, and OTC diets ( P > 0.05 ). After nine days of challenge test with Vibrio alginolyticus, the average cumulative survival rate of shrimp fed GABA50, GABA100, and OTC was significantly higher than that of shrimp fed GABA300 and CON diets ( P < 0.05 ). These results may suggest that 100 mg dietary GABA supplementation (including endogenous GABA, 175.6 mg/kg diet) per kilogram of diet could be the optimum dietary level to replace antibiotics and improve growth performance and disease resistance in whiteleg shrimp L. vannamei.

We investigated the nine experimental diets containing fish meal (FM) and/or fish meal analog (FMA) as the major source of animal protein to determine the optimum FMA level as the substitute of FM protein in the diet of juvenile Japanese eel. In addition, two natural feed additives such as Song-Gang stone (SG) and Yucca meal (YM) were supplemented in the diet to evaluate their efficacy as the immunostimulants. The diets are as follows: 100% FM + 0% FMA in diet (FMA0), 90% FM + 10% FMA in diet (FMA10), 80% FM + 20% FMA in diet (FMA20), 70% FM + 30% FMA in diet (FMA30), 60% FM + 40% FMA in diet (FMA40), FMA0 + 0.4% SG (FMA0SG), FMA0 + 0.1% YM (FMA0YM), FMA20 + 0.4% SG (FMA20SG), and FMA20 + 0.1% YM (FMA20YM). Nine groups of Japanese eel each with three replicates were distributed (initial weight of 9 ± 0.2 g) in rectangular tanks receiving flow through water. Each group of the treatment consisted with 15 fish and fed one of the diets for 8 weeks. At the end of the feeding trial, fish fed with the FMA0 and FMA10 diets showed no significant differences in weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER). Meanwhile, fish fed with FMA20, FMA30, and FMA40 diets showed significantly lower WG, SGR, FE, and PER than the fish fed with the FMA0 (control) diet. In addition, there were no significant differences among fish fed with the SG- and YM-supplemented diet groups. However, lysozyme activities in fish fed with the FMA10, FMA20, FMA30, and FMA40 were significantly lower than the fish fed with the FMA0SG, FMA0YM, FMA20SG, and FMA20YM diets. After 7 days of injection with V. Anguillarum, cumulative survival rates of fish fed with the FMA0SG and FMA0YM diets were significantly higher than the FMA0 diet group. The results revealed that the FMA could replace up to 10% of FM as a protein source in the diet of Japanese eel and both of the natural feed additives (SG and YM) could improve replacing rates of FMA from 10% to 20% without compromising growth and health status of fish.

β-glucan is considered as an effective immunostimulant because of its binding capacity to different receptors on leukocytes leading to the stimulation of immune responses including bactericidal activity, cytokine productivity, and survival fit ability at cellular levels. In response to immune cell surface receptors, β-glucan stimulates to release cytokines and chemokines. It has been found that these signaling proteins eventually stimulate the immunocompetent cells in fish such as monocytes, macrophages, and neutrophils for killing pathogens by phagocytosis, oxidative burst, and cytotoxic killing activities. They also procreate immunological memories and specific antibodies through activation of T and B lymphocytes. Researchers have proved that β-glucan can modulate some important biochemical (serum hemoglobin, serum protein, and total hemocyte count) and immunological (lysozyme activity, phagocytic activity, oxidative burst activity, and phenoloxidase activity) properties providing more competent immune profile for treating fish and aquatic organisms. β-glucan-supplemented fish showed limited sensitivity of genes involved in acute inflammatory reactions. Findings have shown that β-glucan exerts a positive impact on fish and aquatic organisms’ immunity, enhancing their disease resistance by increasing functional and decreasing deleterious responses. This review focuses on the basic bump of β-glucan on fish and shellfish immunity and recent information on the uses of β-glucan in progressive aquaculture.

Olive flounder (Paralichthys olivaceus) also referred to as bastard halibut is a marine carnivorous species with great commercial value. The production of olive flounder has been dominated by aquac...

Background As the cost of fishmeal continues to rise, there will be a need to optimize the diet by minimizing dietary fishmeal inclusion in aquafeed. In this study, a 7-week experiment was conducted to evaluate soybean meal, fermented soybean meal (soytide), and sesame meal as fishmeal replacers in whiteleg shrimp, Litopenaeus vannamei. Methods A 30%-based fishmeal diet was considered as control (CON), six other diets were prepared by replacing 20% or 40% of fishmeal with soybean meal (SB20 and SB40), fermented soybean meal (ST20 and ST40), or sesame meal (SM20 and SM40) from the CON diet. Twenty shrimp with average initial weight of 0.65 ± 0.05 g (mean ± SD) were randomly distributed into 21 tanks (45 L) and fed four times a day. Water temperature was controlled at 28 ± 1 °C and aeration was provided by air stones. Results Weight gain, specific growth rate, feed efficiency, and protein efficiency ratio of shrimp fed CON showed no significant differences compared to shrimp fed all the other diets. However, growth performance of shrimp fed ST20 diet was significantly higher than those of shrimp fed the SM20 and SM40 diets (P < 0.05). Superoxide dismutase activity (SOD) of shrimp fed CON, ST20, and ST40 diets was significantly higher than those of shrimp fed the SB40 and SM40 diets. But there were no significant differences among shrimp fed CON, SB20, ST20, ST40, and SM20 diets. Also, lysozyme activity of shrimp fed ST20 diet was significantly higher than those of shrimp fed the SB40 and SM40 diets. Although, lysozyme activity of shrimp fed the CON diet was not significantly different compared to shrimp fed all the other experimental diets. Conclusions Therefore, SB, ST, and SM could replace 40% of fishmeal based on growth performance and lysozyme. According to the SOD activity, SB and SM could replace 20% of fishmeal and ST could replace 40% of fishmeal in juvenile whiteleg shrimp Litopenaeus vannamei.

An 8‐week study was conducted to explore the results of Macsumsuk® as a feed additive on the stress tolerance and growth of Litopenaeus vannamei in 15 culture tanks of 36 L each. Three hundred shrimp averaging 0.1 ± 0.01 g were fed with five isonitrogenous (48.38 ± 0.38% CP) diets (in triplicate groups) containing kaolinite (Macsumsuk®) at 0%, 0.3%, 0.6%, 1.2% and 2.4%, namely Mk₀, Mk₀.₃, Mk₀.₆, Mk₁.₂ and Mk₂.₄. Specific growth rate (SGR) and weight gain (WG) of shrimp fed diets Mk₁.₂ and Mk₂.₄ were significantly better than those of shrimp fed diet Mk₀ (p

An eight‐week feeding trial was conducted to evaluate the contribution of biofloc on dietary lipid requirement in whiteleg shrimp Litopenaeus vannamei. Five diets with graded levels of dietary lipid (45, 60, 90, 120 and 150 g/kg) were fed to juvenile shrimp. Final weight, weight gain and specific growth rate of shrimp fed diets with 60, 90 and 120 g/kg lipid levels were significantly higher than those of shrimp fed diets with lipid levels 45 and 150 g/kg (p

This study evaluated the effects of replacing fish oil (FO) with beef tallow (BT) in juvenile olive flounder, Paralichthys olivaceus (3.93 ± 0.07 g), over 8 weeks. Seven diets, consisting of 0, 25, 50, 75, and 100% replacement of FO with BT and 63 and 75.9% replacement supplemented with docosahexaenoic acid (DHA) at 0.9 and 1.1% of 100 g diet, respectively, were distributed into 21 tanks in a semi‐recirculation system with 15 fish per tank. The replacement of FO with BT at the given levels showed no significant changes (p > .05) in growth performance and whole‐body proximate composition. Fish fed the diet of 75.9% replacement with 1.1% DHA supplementation showed the best performance in these measurements among the treatments. Plasma glutamic pyruvic transaminase, cholesterol, high‐ and low‐density lipoproteins, and total protein were not significantly influenced by the replacement of FO with BT. The FO replacement generally resulted in a reduction of eicosapentaenoic acid, DHA, and n‐3/n‐6 polyunsaturated fatty acid ratio in the whole body, whereas the DHA supplementation recovered the level of DHA and the n‐3/n‐6 ratio to those observed in the group fed the 0% replacement diet. Taken together, BT along with DHA supplementation can potentially be a cost‐effective alternative for FO in olive flounder culture.

A 12‐week feeding trial was conducted to investigate the effects of two dietary probiotics; Bacillus subtilis KCTC 2217 or Bacillus licheniformis KCCM 11775 with two prebiotics; mannan oligosaccharide (MOS) or fructooligosaccharide (FOS) in Japanese eel. Fish averaging 12.8 ± 0.47 g (mean ± SD) were randomly distributed into five treatments with triplicate tanks. A basal control diet (CON) and four synbiotic diets supplementing B. subtilis + MOS (BSM), B. subtilis + FOS (BSF), B. licheniformis + MOS (BLM), and B. licheniformis + FOS (BLF). Weight gain and specific growth rate of fish fed all synbiotic diets were higher than those of fish fed CON. Immune‐related gene expression of heat shock protein 70 and immunoglobulin M of fish fed BSF and BLM were significantly higher than those of fish fed CON. Fish fed BSF and BLM had significantly higher intestinal villi length than those of fish fed BLF and CON (p

An eight‐week study was conducted to determine the optimum dietary choline level in juvenile olive flounder, Paralichthys olivaceus. Seven diets were prepared to contain 0, 250, 500, 750, 1,000, 2,000 and 3,000 mg/kg diet. Juveniles (5.9 ± 0.03 g; 5.5 ± 0.4 cm; mean ± SD) were randomly distributed into 21 tanks (25 fish/tank) and fed one of the diets in triplicates. Survival rate of fish fed the diet containing the lowest choline level was significantly lower than those of fish fed the other diets (p

s The present study was conducted to evaluate the effects of different dietary gamma-aminobutyric acid (GABA) levels in Nile tilapia, Orechromis niloticus. Six groups of fish averaging 3.03 ± 0.07 g (mean ± SD) were randomly distributed in 18 rectangular tanks in triplicates. A basal diet without GABA supplementation was used as a control (CON), and the other five diets were prepared by adding 75 mg GABA (GABA144), 75 mg GABA +50 mg heat-killed Lactobacillus paracasei (GABA189L), 150 mg GABA (GABA197), 150 mg GABA +50 mg heat-killed Lactobacillus paracasei (GABA242L), and 600 mg GABA (GABA507) per kg of diet. Actual GABA compositions for CON, GABA144, GABA189L, GABA197, GABA242L and GABA507 diets were 96, 144, 189, 197, 242 and 507 mg kg−1, respectively. After 8 weeks of experiment, weight gain, specific growth rate, feed efficiency and protein efficiency ratio of fish fed GABA189L were significantly higher than those of fish fed CON and GABA5.7 diets (P

Aquaculture has experienced tremendous growth over the last few decades as global production has increased from 16 million tons in 1990 to 110 million tons in 2016. Meanwhile, the modern aquacultur...

Five experimental diets were formulated to evaluate the effects of dietary enzymatically hydrolyzed tuna by-product on growth, non-specific immune responses, and hematology of juvenile rainbow trout (Oncorhynchus mykiss). A basal diet with 50% of fishmeal was used as control (CON) and four other diets replaced 12.5% (TBB12.5), 25% (TBB25), 37.5% (TBB37.5), and 50% (TBB50) of fish meal in the CON diet. Juvenile rainbow trout (4.87 ± 0.05 g) were randomly distributed into 15 tanks (50 L) and fed 3–4% of wet body weight two times a day. At the end of 7 weeks of feeding trial, weight gain, specific growth rate, feed efficiency, and protein efficiency ratio of fish fed CON diet were significantly higher than those of fish fed TB50 diet (P 0.05). There were no significant differences in GPT levels among fish fed CON, TBB12.5, TBB25, and TBB37.5 diets. Also, there were no significant differences in lysozyme, superoxide dismutase, glucose, and total protein levels in all experimental diet (P > 0.05). The broken-line analysis indicated that the minimum dietary level of enzymatically hydrolyzed tuna by-product to replace fishmeal could be 29.7% in rainbow trout. These results indicated that the optimum level of dietary enzymatically hydrolyzed tuna by-product could replace greater than 29.7% but less than 37.5% of fishmeal in juvenile rainbow trout diet.

Background High demand and low supply of fishmeal due to overexploitation of fisheries resources have resulted in a dramatic increase in the price of this ingredient. Olive flounder (Paralichthys olivaceus) commercial feed contains approximately 60% fishmeal and limited success has been achieved in identifying sustainable alternative protein sources for this species. Methods An on-farm feeding trial was conducted to compare a basal diet containing 65% as the control (CONT) with two experimental diets replacing 10% of fishmeal by animal protein (AP10) or 20% of fishmeal by animal and plant protein (APP20). Sub-adult olive flounder averaging 327 ± 9.3 g (mean±SD) were fed one of the three diets in triplicate groups for 16 weeks. Results Weight gain, specific growth rate, feed efficiency, protein efficiency ratio, and survival were not significantly different among fish fed all the experimental diets (P > 0.05). Also, non-specific immune responses (superoxide dismutase and lysozyme activity), serum biochemical parameters, and intestinal villi length were not significantly different among fish fed all the experimental diets (P > 0.05). Conclusions Therefore, based on growth performance, non-specific immune responses, serum biochemical parameters, and intestinal histology, dietary animal and plant protein mixtures could replace up to 20% of fishmeal in the diet of sub-adult olive flounder.

A 9-week feeding trial was conducted to evaluate the optimum dietary level of PROTIDE (PRO), a single-cell protein obtained from the bacteria Corynebacterium ammoniagenes, as a substitute for fish meal in the diet of whiteleg shrimp Litopenaeus vannamei. Five diets were formulated that replaced fish meal at 0% (PRO0), 10% (PRO2), 20% (PRO4), 30% (PRO6) and 40% (PRO8). Fifty shrimp averaging 0.15 ± 0.02 g (mean ± SD) body weight were randomly distributed between 20 experimental tanks and fed one of the five experimental diets. At the end of the experiment, final weight, weight gain, specific growth rate and feed conversion ratio of shrimp fed PRO0 and PRO2 diets were significantly improved compared to those fed PRO6 and PRO8 diets (P

The present study was conducted to evaluate the efficacy of organic acid blends as dietary antibiotic replacer in marine fish olive flounder, Paralichthys olivaceus. Fish averaging 3.5 ± 0.05 g (mean ± SD) were fed one of the four experimental diets: (1) without antibiotic or organic acid (Control/CON); (2) with antibiotic—50 mg oxytetracycline per kg body weight per day (OTC); (3) with organic acid blend A—4 g/kg diet (OAA); and (4) with organic acid blend B—4 g/kg diet (OAB), for 10 weeks. At the end of the experiment, total intestinal bacterial counts in fish‐fed OAA, OAB and OTC were significantly lower than that of fish‐fed CON diet (p

In a 16-week feeding trial, the effects of dietary vitamin E (α-tocopherol, α-Toc) levels on tissue α-Toc concentration, hematology and non-specific immune responses of Japanese eel were examined. Totally five diets were used in this experiment, consisting a basal commercial diet (control) and supplementing 100, 150, 200 or 400 mg α-Toc kg− 1 diet in the form of dl -α-tocopherol acetate. The analyzed α-Toc concentrations of the diets were 32, 112, 158, 212 and 428 mg kg− 1 diet, respectively. For each experimental diet, triplicate groups of fish (initial body weight, 360 g) were fed at a ratio of 2% body weight. At the end of the feeding trial, α-Toc concentration in liver, kidney, muscle and gonad were increased significantly in a dose dependent manner (P

An 8-week feeding trial was conducted to investigate the effects of dietary level of fermented plant-based protein concentrate (FPPC) as a fish meal (FM) replacer on growth, hematology, and non-specific immune responses in juvenile olive flounder. Soybean meal and corn gluten meal pre-treated by acid hydrolysis were mixed by the ratio 1:1, and the mixtures were fermented by Bacillus subtilis at 37 °C and 95% humidity to produce FPPC. Triplicated groups of 20 fish weighing 8.36 ± 0.02 g (mean ± SD) were fed one of the six experimental diets formulated to replace FM with FPPC at 0%, 7.5%, 15%, 22.5%, 30%, and 40% (CON, FPPC7.5, FPPC15, FPPC 22.5, FPPC30, and FPPC40, respectively). Five FPPC diets were supplemented with lysine and methionine to balance amino acids levels as the control diet. After the feeding trial, weight gain, feed efficiency, and specific growth rate of fish fed the FPPC40 diet were significantly lower than those of fish fed the other diets (P

The present experiment was conducted to evaluate the efficacy of an additive derived from the nature as an alternative of dietary antibiotic in Japanese eel, Anguilla japonica. Six experimental diets were formulated to contain no antibiotics or additive (yellow loess/YL) (control/CON), three graded levels of yellow loess at 5 (YL5), 10 (YL10) and 20 g/kg (YL20), oxytetracycline at 5 (OTC) and amoxicillin at 10 g/kg amoxicillin (AMX) of diet. Weight gain (WG) and specific growth rate (SGR) from fish fed CON or YL5 diets were significantly lower than those of fish fed YL20 or OTC diets. Among non-specific enzyme, lysozyme activity of fish fed YL20, OTC or AMX was detected to be significantly higher than that from fish fed CON or YL5 diets, whereas superoxide dismutase (SOD) activity of the fish fed CON was significantly lower than that for fish fed other experimental diets. Challenge test with bacteria, Edwardsiella tarda, showed improved disease resistance among the fish fed different levels of natural additive without any statistical difference from those fed antibiotics (OTC and/or AMX) supplemented diets. Therefore, these results demonstrated the potential of natural feed additive, yellow loess to replace oxytetracycline and/or amoxicillin in Japanese eel, A. japonica.

Three different dietary additives were evaluated based on growth performance, innate immune responses and disease resistance in juvenile Amur catfish Silurus asotus. Four diets were prepared by supplementing 0.4% Song-gang® stone (SG), 0.05% Yucca meal (YM), 0.05% β-glucan (BG) in combination with 0.04% SG and 0.05% BG (SG + BG) to a basal commercial diet (control; CONT). Triplicate groups of fish averaging 4.95 ± 0.05 g were fed one of the test diets between 3 and 5% body weight for 8 weeks. At the end of the feeding trial, weight gain, specific growth rate, feed efficiency and protein efficiency ratio of fish fed SG and SG + BG were significantly higher than those of fish fed the BG and CONT diets (P

We evaluated the effects of some dietary natural mineral materials as an antibiotic replacer based on growth performance, non-specific immune responses and disease resistance in juvenile and subadult rainbow trout, Oncorhynchus mykiss. First experiment, juvenile rainbow trout averaging 2.7 ± 0.02 g (mean ± SD) were fed one of the six experimental diets; a basal commercial diet as a control (CON), CON with oxytetracycline (OTC), with yellow loess (YL), with Macsumsuk® (MS), with Song-Gang® stone (SG) and with barley stone (BS) at 0.4% of each diet. At the end of 8-week feeding trial, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein efficiency ratio (PER) of fish fed YL diet were significantly higher than those of fish fed CON diet. Non-specific immune responses such as superoxide dismutase (SOD), myeloperoxidase (MPO), lysozyme (LYS) activity and oxidative radical production of fish fed YL diet were higher than those of fish fed CON diet. At the end of 15 days of challenge test with Aeromonas salmonicida, average cumulative survival rate of fish fed YL diet was significantly higher than that of fish fed BS and CON diets. However, there were no significant differences among fish fed YL, SG and OTC diets. Second experiment, subadult rainbow trout averaging 261.5 ± 3.5 g (mean ± SD) were fed one of the four experimental diets for 22 weeks: CON, and CON with OTC, YL or SG at 0.4% of each diet. At the end of feeding, growth performance of fish fed SG and YL diets was significantly higher than that of fish fed CON diet. Non-specific immune responses in terms of SOD, MPO, LYS and NBT of fish fed SG and YL diets were significantly higher than those of fish fed CON diet. However, there were no significant differences among the fish fed YL, SG and OTC diets. The results indicate that dietary yellow loess or Song-gang® stone at 0.4% of diet could replace oxytetracycline in juvenile and subadult rainbow trout.

A 10-week feeding trial was conducted to determine the effects of dietary yucca meal supplementation on growth, haematology, non-specific immune responses and disease resistance in juvenile Nile tilapia, Oreochromis niloticus. Six isonitrogenous and isoenergetic experimental diets were formulated to contain 0% (YMS0), 0.1% (YMS0.1), 0.3% (YMS0.3), 0.5% (YMS0.5), 1% (YMS1.0) and 2% (YMS2.0) dietary yucca meal on the dry weight basis. Results of this study showed a higher growth performance for YMS0.1 group with significant differences with YMS0.5, YMS1.0 and YMS2.0 groups. In addition, whole-body protein content of fish fed the YMS0.1 diet was significantly higher as compared to YMS0. Plasma lysozyme activity significantly increased in YMS0.1 group comparing to YMS0 and YMS0.5 groups. Respiratory burst activity of phagocytic blood cells was significantly enhanced when fish were fed the YMS0.1 diet. Results also showed that yucca meal supplementation had moderate effects on glutamic oxaloacetic transaminase and cholesterol levels. After the 14-day challenge test with Aeromonas hydrophila, cumulative survival of fish fed YMS0.1 diet was significantly higher than that of fish fed diet YMS0, YMS1.0 and YMS2.0. These results suggest that the optimum dietary yucca meal inclusion level in the diet of juvenile Nile tilapia could be between 0.1% and 0.14% (23.9~33.4 mg kg−1 saponin) as a feed additive to promote growth, enhance the non-specific immune responses and increase disease resistance.

Investigations were carried out to evaluate and quantify the effects of dietary supplementation with heat-killed (HK) Bacillus sp. SJ-10 (BSJ-10) probiotic (1 × 108 CFU g−1) on the growth and immunity of olive flounder (Paralichthys olivaceus). Flounder (averagely 9.64 g) were divided into two groups, and fed control and HK BSJ-10 (HKBSJ-10)-inoculated diets for 8 weeks. Investigations were carried out on growth and feed utilizations, innate immunity, serum biochemical parameters, microvilli length, and pro- and anti-inflammatory cytokine gene (tumor necrosis factor [TNF]-α, interleukin [IL]-1β, IL-6, and IL-10) transcriptions. Compared to control, HKBSJ-10 diet significantly (P

A 12-week feeding trial was conducted to evaluate inorganic (zinc sulfate; ZnSul) and organic (zinc methionine; ZnMet) forms of dietary zinc (Zn) in beluga sturgeon (Huso huso) with the initial average weight of 8.4 ± 0.29 g (± SD). A diet without Zn supplementation was formulated as the control diet (CON); six other diets were formulated by adding ZnSul or ZnMet at 15, 30, and 60 mg kg−1 diet (ZnSul15, ZnSul30, ZnSul60, ZnMet15, ZnMet30, and ZnMet60, respectively). Final weight (FW), weight gain (WG), and specific growth rate (SGR) of fish fed ZnMet15, ZnMet30, and ZnMet60 diets were significantly higher than those of fish fed the CON diet (P

The present experiment was conducted to evaluate the effects of trace mineral (Cu, Zn, Mn and Fe) premixes from inorganic and chelated (chelated to 2-hydroxy-4-methylthiobutanoic acid or hydroxy analog of methionine; Mintrex™, Novus International Inc., St. Charles, MO, USA) sources, in rockfish, (Sebastes schlegeli). fed diets containing mineral inhibitor phytic acid. Seven isonitrogenous (46% crude protein/CP) and isocaloric (16.63 KJ available energy per g diet) semi-purified diets comprising of a Basal control and diets supplemented either with the inorganic (I) or chelated premix (M) at three different levels of 0.75 (I0.75/M0.75), 1.5 (I1.5/M1.5) and 3 (I3/M3) g kg−1 diets were formulated. Twenty-four fish averaging individual wet body weight of 9 ± 0.2 g (Mean ± SD) were fed one of the experimental diets in quadratic group for 16 weeks. Average weight gain (WG) of fish fed M3 was significantly higher than that of fish fed Basal control and I1.5 diets (P

A 10-weeks of feeding trial was conducted to evaluate the dietary selenium (Se) requirement and toxicity levels in juvenile Nile tilapia, Oreochromis niloticus using seleno-methionine as the source of Se. Graded level of Se-Met were added to the basal diet at 0, 0.25, 0.5, 0.75, 1.0, 2.0, 4.0, 8.0 and 16.0 mg Se/kg diet providing the analyzed Se of 0.30 (Se0.30), 0.55 (Se0.55), 0.73 (Se0.73), 0.82 (Se0.82), 1.04 (Se1.04), 2.06 (Se2.06), 2.95 (Se2.95), 6.31 (Se6.31) and 14.7 (Se14.7) mg Se/kg diet respectively. Twenty fish averaging 1.85 ± 0.1 g (mean ± SD) were fed one of the nine experimental diets in triplicate groups. At the end of the feeding trial, weight gain (WG), specific growth rate (SGR) and feed efficiency (FE) of fish fed Se2.06 were significantly higher than those of fish fed other diets (p 1.06 but Statement of relevance The importance of trace mineral, selenium (Se) supplementation in fish feed formulation has been well accepted since Se from ambient water and feed itself cannot supply the optimal level required by the cultured aquatic species. Even though, Se is typically required in much lower quantity in fish diet but its supplementation at optimum level is a critical issue in fish feed formulation. Scientific reports gathered over last two decades indicate, Se is quite sensitive and proper care should be taken to ensure their inclusion at optimum level in fish feed formulation. The present experiment clearly demonstrated that, freshwater fish juvenile Nile tilapia has a specific requirement level for dietary Se which cannot be met by regular feed and ambient water. Inclusion of dietary Se at optimum level is imperative to promote the maximum growth, tissue saturation and to ensure an optimum enzyme activity in Nile tilapia. Supplementing Se in fish feed beyond the requirement level may have toxic effects in freshwater aquaculture.

A 12-wk feeding trial was conducted to evaluate the effects of the dietary fishmeal analogue (FMA) adding 2% shrimp soluble extract (SSE) on growing rainbow trout, Oncorhynchus mykiss. Fish averaging 146 ± 3.8 g (mean ± SD) were randomly distributed into 500-L aquaria as groups of 20 fish per tank. Fish were fed the experimental diets in triplicate groups to apparent satiation twice a day on a dry matter basis. Each group was fed one of the four experimental diets: control (FM100% + FMA0%), FMA0 (FM100% + FMA0% + SSE2%), FMA12 (FM88% + FMA12% + SSE2%), and FMA24 (FM76% + FMA24% + SSE2%). After the feeding trial, weight gain and specific growth rate of fish fed the FMA0 and FMA12 diets were significantly higher than those of fish fed the FMA24 diet (P < 0.05). Feed efficiency and protein efficiency ratio values of fish fed the control, FMA0, and FMA12 diets were significantly higher than those of fish fed the FMA24 diet (P < 0.05). The values of superoxide dismutase activity showed significantly higher amounts for the FMA0, FMA12, and FMA24 groups than the control group (P < 0.05). Lysozyme activity in the FMA12 group was significantly higher than in the control group (P < 0.05). Therefore, according to our results, FMA with additive SSE can be used up to 12% as a substitute of fishmeal for growing rainbow trout.

A feeding trial was conducted to determine the optimum level and effect of incremental dietary levels of docosahexaenoic acid (DHA, 22:6n-3) on growth and non-specific immune responses in juvenile rock bream, Oplegnathus fasciatus. A basal diet without DHA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g kg−1 DHA. These diets included no eicosapentaenoic acid and/or arachidonic acid contents. The actual DHA concentrations of the diets were 1, 4.8, 8.9, 13.1, 17.6, 21.2 and 41.4 g kg−1 diet (DHA1.0, DHA4.8, DHA8.9, DHA13.1, DHA17.6, DHA21.2 and DHA41.4 respectively). At the end of feeding trial, final body weight, weight gain, specific growth rate and feed efficiency of fish fed the DHA13.1, DHA17.6, DHA21.2 and DHA41.4 diets were significantly higher than those fed the other diets (P

An 8-wk feeding trial was conducted to estimate the optimum dietary protein level and protein-to-energy (P/E) ratio in juvenile parrot fish, Oplegnathus fasciatus. Eight experimental diets were formulated with two energy levels and four protein levels for each energy level. Diets containing crude protein (CP) at 35, 40, 45, and 50% had either 12.5 or 14.6 kJ/g of energy. Fish averaging 7.1 ± 0.06 g (mean ± SD) were fed one of the experimental diets for 8 wk. At the end of the feeding trial, weight gain (WG) of fish fed 45 and 50% CP in the 12.5 kJ/g diet was significantly higher than fish fed the 35% CP diet (P

The present study was conducted to evaluate the effects of dietary protein levels on growth, biometrics, hematology and body composition in juvenile parrot fish Oplegnathus fasciatus. Fish averaging 7.1 ± 0.06 g (mean ± SD) was randomly distributed into 15 net cages (each size: 60 × 40 × 90 cm, W × L × H) as groups of 20 fish. Five isocaloric diets (16.7 kJ/g energy) were formulated to contain crude protein levels (CP) as 35 (CP35), 40 (CP40), 45 (CP45), 50 (CP50) and 60 % (CP60) in the diets. Fish were fed one of the experimental diets at apparent satiation twice a day in triplicate groups. At the end of 8-week feeding trial, weight gain (WG) of fish fed with CP50 and CP60 diets were significantly higher than those of fish fed with CP35, CP40 and CP45 diets. Fish fed with CP45, CP50 and CP60 diets had higher feed efficiency (FE) and specific growth rate (SGR) than those of fish fed with CP35 and CP40 diets. Protein retention efficiency (PRE) decreased with increase of dietary protein levels among fish fed with the experimental diets. Whole-body crude protein and lipid contents increased with the dietary protein level up to CP50 diet. In conclusion, analysis of variance (ANOVA) revealed that the optimum dietary protein level could be 50 % for maximum growth of juvenile parrot fish, while the broken-line analysis of WG suggested that the level could be 48.5 %, in a diet containing 16.7 kJ/g energy.

The present experiment was conducted to evaluate the efficacy of trace minerals (Cu, Zn and Mn) premixes from inorganic and chelated (chelated to 2-hydroxy-4-methylthiobutanoic acid or hydroxy analog of methionine; Mintrex™) sources, in juvenile Pacific white shrimp, ( Litopenaeus vannamei ) fed plant protein based practical diets. Eight experimental diets comprising a trace minerals (Cu, Zn and Mn) deficient Basal control, and diets supplemented with the trace mineral premixes at four different levels of 2.5 (M 2.5 ), 5 (M 5 ), 7.5 (M 7.5 ) and 8.5 g/kg (M 8.5 ) from chelated source and at three different levels of 5 (I 5 ), 8.5 (I 8.5 ) and 20 g/kg (I 20 ) from inorganic source were formulated. Eleven numbers of juvenile shrimp averaging 0.6 ± 0.01 g (mean ± SD) were fed one of the eight experimental diets in triplicate groups for 8 weeks. At the end of the feeding trial, shrimp fed M 2.5 and I 8.5 diets exhibited the similar final weight (FW) and weight gain (WG) ( P 5 compared to I 8.5 diet ( P Zn super oxide dismutase (Cu Zn SOD) from the serum and hepatopancreas tissue was recorded to be peaked for the group of shrimp fed M 5 diet. Moreover, plasma protein and glucose levels were recorded to be similar between the groups of shrimp fed M 2.5 and I 20 diets ( P L. vannamei ) fed plant protein based diets. Statement of relevance The significance of trace mineral bioavailability has become more important as the composition of majority of commercial fish feed has been changing and there is an increased use of dietary plant protein. As a result, the bioavailability of trace minerals is being adversely affected by the presence of antagonistic factor such as phytic acid in plant protein. Even though, our knowledge in fish nutrition has advanced significantly, the information on trace minerals requirement is still limited and fragmentary. Inorganic form (sulfate/nitrate) of trace mineral has traditionally been used in aquafeed formulation. However, the limited bioavailability of inorganic source of trace mineral due to its higher affinity to antinutrients has hastened the search for alternative form of inorganic trace minerals. Overall performance observed in the present experiments vouched the potential benefit of using chelated trace mineral, Cu, Zn & Mn premix in marine shrimp, Pacific white shrimp to promote the optimum growth, trace minerals saturation in shrimp body and tissue as well as to ensure the optimum enzyme activity and health of cultured shrimp. The present experiment opens a new avenue to compare the efficacy of inorganic and chelated source of trace minerals in other commercially important marine and fresh water fish species. Whereas, the sustainability issue has put a new dimension in aquafeed formulation with a wide array of new ingredients and additives, on the other hand, the importance of basic nutrient such as trace minerals is still in sideline. Substantial investment and integrated scientific efforts are warranted to bridge the knowledge gap and further improve our understandings on the significance of dietary trace mineral in fish nutrition and health at the least cost to environment.

This study evaluated the dietary lysine requirement by measuring the plasma free lysine concentrations in rainbow trout, Oncorhynchus mykiss after dorsal aorta cannulation. A basal diet containing 36.6 % crude protein (29.6 % crystalline amino acids mixture, 5 % casein and 2 % gelatin) was formulated to one of the seven L-amino acid based diets containing graded levels of lysine (0.72, 1.12, 1.52, 1.92, 2.32, 2.72 or 3.52 % dry diet). A total of 35 fish averaging 512 ± 6.8 g (mean ± SD) were randomly distributed into seven groups with five fish in each group. After 48 h of feed deprivation, each group of fish was fed one of the experimental diets by intubation at 1 % body weight. Blood samples were taken at 0, 5 and 24 h after intubation. Post-prandial plasma free lysine concentrations (PPlys, 5 h after intubation) of fish fed diets containing ≥ 2.32 % lysine were higher than those of fish fed diets containing ≤ 1.92 % lysine. Post-absorptive free lysine concentrations (PAlys, 24 h after intubation) of fish fed diets containing 2.32 and 3.52 % lysine were higher than those of fish fed diets containing ≤ 1.52 % lysine. The broken-line regression analysis on the basis of PPlys and PAlys indicated that the lysine requirement of rainbow trout could be 2.34 and 2.20 % in diet. Therefore, these results strongly suggested that the dietary lysine requirement based on the broken-line model analyses of PPlys and PAlys could be greater than 2.2 but less than 2.34 % (corresponding to be 6.01 % ≤, but ≤ 6.39 % in dietary protein basis, respectively) in rainbow trout. Also, these results shown that the quantitative estimation of lysine requirement by using PPlys and PAlys could be an acceptable method in fish.

A feeding trial was conducted to evaluate the optimum dietary level and the essentiality of arachidonic acid (ARA, 20:4n-6) based on growth and non-specific immune responses in Japanese eel, Anguilla japonica . A basal ARA free commercial diet was used as a control, and four other diets were prepared by supplementing 0.3, 0.6, 0.9 or 1.5% ARA. The analyzed ARA concentrations of the diets were 0.00, 0.33, 0.71, 1.06 and 1.65% diet (ARA 0 , ARA 0.33 , ARA 0.71 , ARA 1.06 and ARA 1.65 ), respectively. Triplicate groups of fish (initial body weight, 157 ± 2.5 g) were fed one of 5 experimental diets at a ratio of 4% body weight for 12 weeks. At the end of the feeding trial, final weight, weight gain, specific growth rate and feed efficiency of fish fed the ARA 0.71 diet were significantly higher than those of fish fed the ARA 0 , ARA 0.33 and ARA 1.65 diets ( P 1.65 diet was significantly higher than those of fish fed the ARA 0 and ARA 0.33 diets. However, there were no significant differences in superoxide dismutase activity among fish fed diets ARA 0.71 , ARA 1.06 and ARA 1.65 . Fish fed the ARA 1.06 diet showed significantly higher lysozyme activity than those of fish fed the ARA 0 and ARA 0.33 diets. However, there were no significant differences in lysozyme activity among fish fed the ARA 0.71 , ARA 1.06 and ARA 1.65 diets. Therefore, the optimum dietary ARA level could be greater than 0.71% but less than 0.92%. Also, these results may indicate that dietary ARA could be one of the essential fatty acids in Japanese eel. Statement of relevance The findings showed the essentiality of an appropriate arachidonic acid supplementation level for optimum growth of Japanese eel.

Fishmeal is an important source of protein in the fish diet, but its supply is unstable due to environmental pollution and overfishing of anchovy and herring. In addition, the disease outbreak of fish has been increased, and the abuse of antibiotics and vaccines has been becoming a problem for residual substances. Therefore, studies that address diets with reduced fishmeal content and additives that can increase efficiency and replace antibiotics are needed. Hence, in this study, the probiotics bacteria Bacillus sp. SJ-10 (BSJ-10) and Lactobacillus plantarum (LP) were heat-killed (HK) used as additives in a low-fishmeal diet. The two bacteria with a 45 % fishmeal diet were added at a concentration of 3.34 × 108 CFU/mL, and both of probiotics bacteria were mixed and added to the same concentration in order to produce the diet for HK BSJ-10 (HKBSJ-10), HK LP (HK-LP), and MIX (HKBSJ-10 + HK-LP) groups. We raised four replicates of juvenile olive flounder for 8 weeks. In the HKBSJ-10 group, the plasma insulin, GH, and IGF-I level were higher than the other groups (P

In an eight-week feeding trial, encapsulated sodium butyrate (ESB), gamma-aminobutyric acid (GAB), selenium-yeast (SeY), yeast extract nucleotides (YEN), yucca meal (YUM), song-gang stone (SGS) and protease (PRT) were evaluated as functional feed additives in a low fishmeal (FM) diet for olive flounder Paralichthys olivaceus. Eight experimental diets were fed to 5.26 ± 0.17 g (mean ± SD) juvenile olive flounder in triplicates. A low-FM basal diet without feed additive was considered as control (CON); seven other diets were prepared by adding 4 g ESB, 158 mg GAB, 2 g SeY, 4 g YEN, 1.5 g YUM, 4 g SGS, and 175 mg PRT per kg of basal diet. Weight gain, specific growth rate, feed efficiency, and protein efficiency ratio of fish fed diets YEN, GAB, and SGS were significantly higher than those of fish fed CON diet (P .05). Heat shock protein 70 gene expression of fish fed YEN and SeY was significantly higher than those of fish fed the CON diet. Intestinal villi length of fish fed YEN, GAB, SGS, and ESB was significantly higher than those of fish fed CON. Also, intestinal trypsin activity of fish fed YEN, GAB, SGS, ESB, and PRT was significantly higher than those of fish fed CON diet (P

A 12-week feeding trial was conducted to evaluate the synergistic effects of dietary vitamin E, α-Tocopheryl acetate (α-TA) and arachidonic acid, 20:4n-6 (ARA) on non-specific immune responses and tissue concentrations in female Japanese eel broodstock, Anguilla japonica. Four experimental diets (in a 2 × 2 factorial design) were formulated to contain two different levels of α-TA and ARA. A basal commercial diet without supplementation was used as the control (E0ARA0) with three other diets being formulated by addition of 200 mg α-TA kg−1 (E200ARA0), 5 mg ARA kg−1 (E0ARA5), and 200 mg α-TA + 5 mg ARA kg−1 (E200ARA5). Four triplicate groups of 10 fish averaging 279 ± 9.0 g (mean ± SD) were randomly assigned to twelve 150-L tanks with a constant flow rate of 4 L min−1. At the end of the trial superoxide dismutase (SOD) activity of fish fed E200ARA5 were significantly higher than those of fish fed E0ARA0 and E200ARA0 (P > .05). Myeloperoxidase (MPO) and Lysozyme activities showed a similar trend with SOD activity, though there were no significant differences among the activities of fish fed experimental diets (P

This study evaluated the synergistic effects of dietary Bacillus subtilis WB60 and mannanoligosaccharide (MOS) in juvenile Japanese eel, Anguilla japonica. Seven treatment diets were formulated to contain three different levels of B. subtilis (0.0, 0.5, and 1.0 × 107 CFU/g diet denoted as BS0, BS0.5, and BS1, respectively) with two MOS levels (0 and 5 g/kg diet denoted as M0 and M5, respectively), and one diet with oxytetracycline (OTC) at 5 g/kg diet. Each diet (BS0M0 (CON), BS0M5, BS0.5M0, BS0.5M5, BS1M0, BS1M5, and OTC) was fed to triplicate groups of 20 fish averaging 9.00 ± 0.11 g (mean ± SD) for eight weeks. Average weight gain, feed efficiency, specific growth rate and protein efficiency ratio of fish fed the BS0.5M5 and BS1M5 diets were significantly higher than those of fish fed CON, BS0.5M0 and OTC diets (P 0.05). Therefore, the results for growth performance, non-specific immune responses, intestinal morphology, and disease resistance demonstrated that supplementation of B. subtilis at 0.5 × 107 CFU/g diet and mannanoligosaccharide at 5 g/kg diet could have beneficial synergistic effects in Japanese eel. The isolated probiotic from eel and the selected prebiotic could lead to the development of a specific and potential synbiotic in Japanese eel aquaculture.

Bacillus sp. SJ-10 (BSJ-10) was identified from traditional Korean fermented fish, the previously recognized prebiotic β-glucooligosaccharides (BGO), and their combination as a synbiotic were prepared to evaluate their individual and synergistic effects in olive flounder (Paralichthys olivaceus). Four diets (one control and three treatments) were formulated containing neither BSJ-10 nor BGO (control), 1 × 108 CFU g −1 BSJ-10 (BSJ-10), 0.1% BGO (BGO), and 1 × 108 CFU g−1 BSJ-10 + 0.1% BGO (BSJ-10 + BGO). Triplicates of 15 fish (weight 10 ± 0.25 g) were randomly allocated to the four diet groups and fed one of the diets for 8 weeks. At the end of the experiment, fish weight gain (WG), specific growth rate (SGR), feed conversion ratio, and protein efficiency ratio in BSJ-10, BGO and BSJ-10 + BGO diets were positively modulated (P

A 12 weeks of feeding trial was conducted to evaluate the effects of different levels of dietary yellow loess as an antibiotic (oxytetracycline) replacer in rainbow trout, Oncorhynchus mykiss. Five experimental diets were formulated to contain no antibiotics or yellow loess (control/CON), three graded levels of yellow loess 5 (YL5), 10 (YL10) and 20 g YL kg−1 diet (YL20) and oxytetracycline at 5 g OTC kg−1 diet. Forty-five fish averaging 39.4 ± 1.6 g (mean ± SD) were randomly distributed in to 15 aquaria. Triplicate groups of fish were fed one of the experimental diets at 1.5 ~ 1.9% of wet body weight per day. At the end of the feeding trial, average weight gain (WG) and specific growth rate (SGR) from fish fed CON diet were significantly lower than those from fish fed YL10, YL20 or OTC diets (P

An 8-week feeding trial was conducted to evaluate the synergistic effects of dietary vitamin E and selenomethionine (SeMet) on induced methylmercury (MeHg) toxicity in juvenile olive flounder Paralichthys olivaceus. Nine semi-purified diets were formulated to contain three different vitamin E levels as DL-α-tocopheryl acetate (0, 100 and 200 mg TAkg−1 diet) and three different selenium (Se) levels (0, 2 and 4 SeMet mg kg−1 diet) on the constant mercury toxicity level (20 mg MeHgkg−1 diet). Nine experimental diets, in a 32 factorial design (E0Se0, E0Se2, E0Se4, E100Se0, E100Se2, E100Se4, E200Se0, E200Se2 and E200Se4), were fed to triplicate groups of fish averaging 2.3 ± 0.04 g (mean ± SD) in the semi-recirculation system. After 8 weeks of feeding trial, vitamin E and Se showed significant effects on weight gain (WG) of fish (P