Evaluation of Fermented Soybean Curd Residues as an Energy Source in Diets for Juvenile Olive Flounder, Paralichthys olivaceus

A 10‐wk feeding experiment was conducted to evaluate the potential use of fermented soybean curd residues (FSCR) as an energy source in diets for juvenile olive flounder, Paralichthys olivaceus. Five isonitrogenous and isoenergetic diets were formulated to contain dry soybean curd residues to replace wheat meal (WM) at the levels of 0, 25, 50, 75, and 100% (FSCR₀, FSCR₂₅, FSCR₅₀, FSCR₇₅, and FSCR₁₀₀, respectively). Fish averaging 6.00 ± 0.07 g (mean ± SD) were randomly distributed into 15 aquaria as groups of 15 fish and fed the experimental diets in triplicate at a rate of 4–5% of wet body weight per day twice daily on dry matter basis. At the conclusion of the feeding trial, weight gain (WG) and specific growth rate (SGR) of fish fed diet FSCR₂₅ were significantly higher than those of fish fed diets FSCR₅₀, FSCR₇₅, and FSCR₁₀₀ (P < 0.05); however, there were no significant differences in WG and SGR among fish fed diets FSCR₀ and FSCR₂₅ and among those fed diets FSCR₀ and FSCR₅₀. Feed efficiency and protein efficiency ratio of olive flounder fed diet FSCR₂₅ were significantly higher than those of fish fed diets FSCR₅₀, FSCR₇₅, and FSCR₁₀₀ (P < 0.05); however, there were no significant differences in these parameters among fish fed diets FSCR₀ and FSCR₂₅ and among those fed diets FSCR₀, FSCR₅₀, FSCR₇₅, and FSCR₁₀₀. Hematological characteristics, condition factor, hepatosomatic index, and survival rate of fish fed FSCR₀ were not significantly different from those of fish fed the other diets. These results indicated that FSCR could replace up to 50% WM as an energy source in juvenile olive flounder diets based on ANOVA test.     

Effect of dietary protein, lipid and carbohydrate ratio on growth, feed efficiency and body composition of pikeperch Sander lucioperca fingerlings

Pikeperch Sander lucioperca fingerlings were fed nine practical diets containing three levels of protein (P=34%, 43% and 50%), lipid (L=10%, 16% and 22%) and carbohydrate (C=10%, 15% and 20%) for 10 weeks in a recirculating water system at 23°C. Dietary treatments were distributed by orthogonal design with dietary energy content ranging from 15.5 to 23.1 MJ kg^?1 diet. Significant differences (P<0.05) in weight gain (%) and feed efficiency (FE) were observed after feeding trial. Relatively low growth and FE were found in fish fed diets containing 34% dietary protein level compared with that of fish fed diets with 43–50% protein levels, suggesting that 34% dietary protein probably is below the protein requirements of pikeperch fingerlings. Fish fed diets containing P43L10C15, P43L22C20 and P50L16C20 had significantly (P<0.05) higher weight gain and FE than fish fed the diets containing other dietary P/L/C ratios. There was no significant difference in weight gain and FE between fish fed diets of P43L10C15, P43L22C20 and P50L16C20. These results may indicate that pikeperch require at least 43% of dietary protein for adequate growth and FE, and considering the fish growth and feed ingredient cost P43L10C15 diet is more cost‐effective formulation for pikeperch fingerling. However, protein efficiency was not significantly affected by dietary P/L/C ratio.     

Effects of the Dietary Fermented Tuna By‐product Meal on Growth,Blood Parameters,Nonspecific Immune Response,and Disease Resistance in Juvenile Olive Flounder,Paralichthys olivaceus

This study evaluated the effects of dietary fermented tuna by‐product meal (FTBM) in juvenile olive flounder, Paralichthys olivaceus. Five diets were formulated to replace fishmeal (FM) with FTBM at 0% (FTBM₀), 12.5% (FTBM_12.5), 25.0% (FTBM₂₅), 37.5% (FTBM_37.5), or 50% (FTBM₅₀). After 8 wk, weight gain, specific growth rate, and feed efficiency of fish fed FTBM₀ and FTBM_12.5 diets were significantly higher than fish fed the other diets (P < 0.05). Also, mean cumulative survival rates (%) of fish fed the FTBM₀ and FTBM_12.5 diets were significantly higher than those fed FTBM₅₀ diet at Day 9 postchallenge with Edwardsiella tarda (P < 0.05). Protein efficiency ratio of fish fed FTBM₀ and FTBM_12.5 diets was significantly higher (P < 0.05) than fish fed diets FTBM_37.5 and FTBM₅₀. Broken‐line regression analysis of weight gain showed an optimal FM replacement level of 10.65% with FTBM. Therefore, the optimal dietary inclusion of FTBM in juvenile olive flounder diets could be greater than 10.65% but less than 12.5% without any adverse physiological effects on fish health.     

Use of Fermented Fisheries By-products and Soybean Curd Residues Mixture as a Fish Meal Replacer in Diets of Juvenile Olive Flounder, Paralichthys olivaceus

A 10‐wk feeding trial was conducted to evaluate the potential use of fermented fisheries by‐products and soybean curd residues mixture (FFSM) as a partial replacement for fish meal (FM) in the diet of juvenile olive flounder, Paralichthys olivaceus. Five experimental diets were formulated with FFSM replacing 0, 15, 30, 45, and 60% of the FM protein (FFSM₀, FFSM₁₅, FFSM₃₀, FFSM₄₅, and FFSM₆₀, respectively). Juvenile olive flounder averaging 5.99 ± 0.08 g (mean ± SD) were randomly distributed into aquaria at 15 fish/aquarium, with three replicate aquaria for each experimental diet. Weight gain (WG) of fish fed FFSM₀, FFSM₁₅, and FFSM₃₀ was significantly higher than that of fish fed FFSM₄₅ and FFSM₆₀ (P < 0.05). Also, WG of fish fed FFSM₄₅ was significantly higher than that of fish fed FFSM₆₀ (P < 0.05). There were no significant differences in WG among fish fed FFSM₀, FFSM₁₅, and FFSM₃₀ (P > 0.05). Specific growth rate (SGR) of fish fed FFSM₁₅ was significantly higher than that of fish fed FFSM₄₅ and FFSM₆₀ (P < 0.05). Also, SGR of fish fed FFSM₀, FFSM₁₅, FFSM₃₀, and FFSM₄₅ was significantly higher than that of fish fed FFSM₆₀ (P < 0.05). There were no significant differences in SGR among fish fed FFSM₀, FFSM₁₅, and FFSM₃₀ and among those fed FFSM₀, FFSM₃₀, and FFSM₄₅ (P > 0.05). Feed efficiency (FE) and protein efficiency ratio (PER) of fish fed FFSM₆₀ were significantly lower than those of fish fed FFSM₀, FFSM₁₅, FFSM₃₀, and FFSM₄₅ (P < 0.05); however, there were no significant differences in FE and PER among fish fed FFSM₀, FFSM₁₅, FFSM₃₀, and FFSM₄₅. Hepatosomatic index of fish fed FFSM₀, FFSM₁₅, and FFSM₃₀ was significantly higher than that of fish fed FFSM₆₀ (P < 0.05); however, there were no significant differences among fish fed FFSM₀, FFSM₁₅, FFSM₃₀, and FFSM₄₅ and among those fed FFSM₄₅ and FFSM₆₀. No significant differences were observed in condition factor and survival rate among all dietary groups tested. The whole‐body proximate composition averaged 75.0 (% dry matter basis [DM]), 8.66 (% DM), 16.38 (% DM), and 76.1%, for crude protein, crude lipid, ash, and moisture, respectively. Based on growth performance, the FFSM could replace up to 30% FM protein by the ANOVA test; however, broken‐line model analysis indicated 28.7% as an optimum replacement level in juvenile olive flounder diets.     

Evaluation of Toxicity of Dietary Chelated Copper in Juvenile Olive Flounder,Paralichthys olivaceus,Based on Growth and Tissue Copper Concentration

The present study was conducted to determine the safe and toxic levels of dietary copper in juvenile olive flounder, Paralichthys olivaceus, fed Mintrex^® copper, a chelated dietary copper source. Fish averaging 3.8 ± 0.13 g (mean ± SD) were fed 1 of 10 diets (n = 3) containing 7 (Cu₀), 10.4 (CuM₅), 15.8 (CuM₁₀), 24.9 (CuM₂₀), 43.4 (CuM₄₀), 82.1 (CuM₈₀), 158 (CuM₁₆₀), 308 (CuM₃₂₀), 658 (CuM₆₄₀), and 1267 (CuM₁₂₈₀) mg Cu/kg diet. At the end of 12 wk of feeding trial, weight gain (WG), specific growth rate, and protein efficiency ratio of fish fed CuM₅ and CuM₁₀ diets were significantly higher than those fed CuM₈₀, CuM₁₆₀, CuM₃₂₀, CuM₆₄₀, and CuM₁₂₈₀ diets (P < 0.05). Survival of fish fed Cu₀, CuM₅, CuM₁₀, CuM₂₀, and CuM₄₀ diets was significantly higher than those of fish fed CuM₃₂₀, CuM₆₄₀, and CuM₁₂₈₀ diets. Whole‐body lipid content of fish decreased while whole‐body ash increased with dietary copper levels. Whole‐body and tissue copper concentrations increased with dietary copper levels. Although ANOVA test suggested that the toxic level of dietary Cu in juvenile olive flounder, P. olivaceus, could be 320 mg/kg diet, broken‐line analysis of WG indicated a level of 286 mg/kg diet when Mintrex^®Cu is used as the dietary copper source.     

Assessing the Effects of Dietary Inclusion of Hydrolyzed Soy Protein on the Growth,Nutrient Retention,Body Composition,and Serum Hormone of Juvenile Starry Flounder,Platichthys stellatus

Enzymatic hydrolysis of soy protein has the potential to be an excellent protein source in marine fish feeds. Here we assessed the effects of different inclusion levels of hydrolyzed soy protein (HSP) on growth performance, nutrient retention, body composition, and serum hormone levels in juvenile starry flounder to define HSP utilization. Five isoenergetic and isoprotein diets were formulated with 0 (control), 10, 20, 30, and 40% HSP (SP10–40) to replace 0, 25, 50, 75, and 100% soy protein concentrate (SPC), respectively. At the end of the feeding trial, fish fed diets SP20 and SP30 had significantly increased weight gain, percent weight gain, and feed efficiency (FE) compared with fish fed the control diet (P < 0.05). Diets SP20 and SP30 supported significantly higher levels of protein retention, and diet SP20 significantly increased energy retention (P < 0.05) in the fish offered these diets. In terms of nutritional composition of whole fish, feeding diets SP20 and SP30 increased crude protein content (P < 0.05) and diets SP10, SP20, and SP30 increased ash content (P < 0.05). Fish fed diets SP20 and SP30 had higher serum insulin‐like growth factor 1 (IGF‐1) level than that of the control treatment (P < 0.05). When SPC was included at 40% of the diet, 20–30% HSP (43% soluble nitrogen) is recommended to replace 50–75% SPC for maximal growth performance and FE of starry flounder.     

Natural dietary additive yellow loess as potential antibiotic replacer in Japanese eel,Anguilla japonica: Effects on growth,immune responses,serological characteristics and disease resistance against Edwardsiella tarda

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.     

Optimum Dietary Protein Level and Protein‐to‐energy Ratio for Growth of Juvenile Parrot Fish,Oplegnathus fasciatus

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 < 0.05). WG of the fish fed 45 and 50% CP in the 14.6 kJ/g diet was significantly higher than fish fed the 35 and 40% CP diets (P < 0.05). Fish fed the 14.6 kJ/g diet had a higher WG compared with fish fed the 12.5 kJ/g diet at all CP levels. Feed efficiency (FE) and specific growth rate (SGR) showed a similar trend to the WG. WG, FE, and SGR improved with increasing dietary protein levels up to 45% and remained constant at 50% CP for both energy levels. However, protein efficiency ratio was negatively related to dietary protein levels. The results suggested that the optimum level of protein and the optimum P/E ratio for juvenile parrot fish should be 45% and 31.1 mg protein/kJ, respectively, in a diet containing 14.6 kJ/g energy.     

Evaluation of Experimental and Practical Diets for Bluegill Lepomis macrochirus and Hybrid Bluegill L. cyanellus × L. macrochirus

Two experiments were conducted to identify appropriate experimental and practical diets for bluegill Lepomis macrochirus and hybrid bluegill L. cyanellus × L. macrochirus reared in aquaria. In the first study, four experimental diets and five commercial diets were evaluated in juvenile hybrid bluegill initially weighing 4.8 g/fish. The experimental diets contained casein (CAS), casein + gelatin (CAWGEL), casein + L‐arginine‐HCI (CAS/ARG), or casein + gelatin + crystalline amino acids (CAS/AA) as sources of crude protein. The commercial diets included three diets formulated to meet the nutritional requirements of rainbow trout Oncorhynchus mykiss and two diets formulated to meet the nutritional requirements of channel catfish Ictalurus punctatus. Each diet was fed twice daily at a rate of 4% of body weigh/d to triplicate groups of fish. At the end of the 8‐wk feeding trial, weight gain was significantly higher in fish fed the best commercial rainbow trout diets (205–217%) compared to fish fed diets formulated for channel catfish (87–104%). Weight gain and feed efficiency (FE) of fish fed the experimental diets (5346% and 0.19–0.32, respectively) were significantly lower than those of fish fed the commercial rainbow trout diets (143–217% and 0.49–0.64, respectively). In the second experiment, the same dietary treatments were fed for 8 wk to juvenile bluegill initially weighing 3.7 g/fish. Each diet was fed twice daily at a rate of 4% of body weight/d to triplicate groups of fish. Weight gain was significantly higher in fish fed commercial trout diets (291–402%) compared to fish fed diets formulated for channel catfish (164–191%). Weight gain and FE of fish fed CAS/ARG were significantly higher than those of fish fed the commercial catfish diets, but significantly lower than those of fish fed the best commercial trout diets. Results of this study indicate that commercial rainbow trout diets are preferable to commercial channel catfish diets for culture of bluegill and hybrid bluegill. More research is needed to identify appropriate experimental diets for this group of fishes.     

Reevaluation of the Dietary Protein Requirements and Optimum Dietary Protein to Energy Ratios in Japanese Eel, Anguilla japonica

A 2 × 3 factorial design was used to reevaluate the dietary protein requirements and to determine the optimum dietary protein to energy (P/E) ratios in Japanese eel, Anguilla japonica, reared in the recirculating system. For each of two experiments, six experimental diets (₄₅P₁₆, ₄₅P₁₇, ₄₅P₁₉, ₅₀P₁₆, ₅₀P₁₇, and ₅₀P₁₉) were formulated and prepared to contain two protein levels (45 and 50%) and three energy levels (16, 17, and 19 kJ/g diet) at each protein level. In the first experiment, glass eel of initial weight 0.1 ± 0.02 g (mean ± SD) were used, while the second experiment was conducted with juvenile eel of initial weight 15.0 ± 3 g (mean ± SD). The first and second experimental periods were 6 and 16 wk for the glass and juvenile eel, respectively. At the end of the first experiment, there were no protein, energy, and their interaction effects. Also, there were no significant differences in weight gain (WG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) for glass Japanese eel fed all diets. Although there were no significant differences in growth parameters of glass eel fed all experimental diets, these parameters were higher for fish fed ₅₀P₁₆ than for fish fed the other diets. For the second experiment, there were significant protein effects on WG, SGR, and PER (P < 0.05). However, there were neither significant energy effects nor protein and energy interaction effects on WG, SGR, FE, and PER. Fish fed ₄₅P₁₉ had a higher WG, SGR, and PER than did fish fed ₄₅P₁₆, ₅₀P₁₆, and ₅₀P₁₉ (P < 0.05). However, there were no significant differences in growth parameters among fish fed ₄₅P₁₆, ₄₅P₁₇, ₅₀P₁₆, ₅₀P₁₇, and ₅₀P₁₉ and among those fed ₄₅P₁₇, ₄₅P₁₉, and ₅₀P₁₇. These results may indicate that the optimum dietary protein requirement and the P/E ratio could be 44.3% and 24.1 mg protein/kJ (₄₅P₁₉), respectively, in juvenile Japanese eel, based on WG, SGR, and PER.     

Effects of different dietary levels of L-ascorbyl-2-polyphosphate on growth and tissue vitamin C concentrations in juvenile olive flounder, Paralichthys olivaceus (Temminck et Schlegel)

This experiment was conducted to study the effects of different dietary levels of vitamin C, L‐ascorbyl‐2‐polyphosphate (ASPP), on growth and tissue vitamin C concentrations in juvenile olive flounder, Paralichthys olivaceus (Temminck et Schlegel). Fish were fed one of six semi‐purified diets containing an equivalent of 0, 25, 50, 75, 150, or 1500 mg ascorbic acid (AA) kg^?1 diet (C₀, C₂₅, C₅₀, C₇₅, C₁₅₀ or C₁₅₀₀) in the form of ASPP for 12 weeks. Weight gain (WG) and protein efficiency ratio (PER) of fish fed the C₀ diet were significantly lower than those of fish fed the other diets (P < 0.05), and WG and PER of fish fed the C₂₅, C₅₀ and C₇₅ diets were significantly lower than those of fish fed the C₁₅₀₀ diet (P < 0.05). Fish fed the C₀ diet exhibited vitamin C deficiency symptoms such as anorexia, scoliosis, cataract, exophthalmia and fin hemorrhage at the end of the 12‐week test. After 12 weeks of the feeding trial, AA concentrations from gill, kidney, and liver of fish fed the C₀, C₂₅, C₅₀ and C₇₅ diets were significantly lower than those of fish fed the C₁₅₀ and C₁₅₀₀ diets (P < 0.05). Based on broken line analyses for WG and PER, the optimum dietary levels of vitamin C were 91 and 93 mg AA kg^?1 diet respectively. These findings suggest that the dietary vitamin C requirement could be 93 mg AA kg^?1 diet to support reasonable growth, and greater than 150 mg AA kg^?1 diet may be required for AA saturation of major tissues for juvenile olive flounder under experimental conditions.     

Evaluation of Dietary Fishmeal Analogue with Addition of Shrimp Soluble Extract on Growth and Nonspecific Immune Response of Rainbow Trout,Oncorhynchus mykiss

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.     

Effects of dietary protein levels on growth performance and body composition of juvenile parrot fish, <Emphasis Type="Italic">Oplegnathus fasciatus</Emphasis>

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.     

Effects of dietary fermented by‐product of mushroom,Pleurotus ostreatus,as an additive on growth,serological characteristics and nonspecific immune responses in juvenile Amur catfish,Silurus asotus

The present experiment was conducted to evaluate the efficacy of dietary fermented by‐product of mushroom, Pleurotus ostreatus, (FBPM) as an additive in juvenile Amur catfish, Silurus asotus. Five diets were formulated to contain 0%, 0.1%, 0.2%, 0.4% and 0.8% (FBPM₀, FBPM_0.1, FBPM_0.2, FBPM_0.4 and FBPM_0.8 respectively) of FBPM. Fifteen fish averaging 5.7 ± 0.1 g (Mean ± SD) were fed one of the five diets in triplicate groups at 3–4% of wet body weight/day for 8 weeks. Average weight gain (WG) and specific growth rate (SGR) of fish fed FBPM_0.1 and FBPM_0.2 diets were significantly higher than those of fish fed FBPM₀. Hematocrit contents of fish fed FBPM_0.2 were significantly higher than that of fish fed FBPM₀. Lysozyme activity of fish fed FBPM_0.1 was significantly higher than those of fish fed FBPM₀, FBPM_0.2, FBPM_0.4 and FBPM_0.8, while chemiluminescent (CL) responses of fish fed FBPM_0.2 was significantly higher than those of fish fed FBPM₀, FBPM_0.1, FBPM_0.4 and FBPM_0.8. Broken line regression analysis of WG showed that optimum dietary FBPM levels based on WG could be 0.11%. Therefore, these results suggested that the optimum dietary inclusion level of mushroom, Pleurotus ostreatus by‐product fermented using lactobacillus and yeast could be greater than 0.11% but less than 0.2% based on WG and immunological responses in Amur catfish, Silurus asotus without any adverse effects on serological characteristics and body composition.     

The growth and gonadal maturation of the African catfish, Clarias gariepinus (Burchell) broodstock fed differently heated soybean-based diets

An investigation was carried out to assess the growth and gonadal maturation of Clarias gariepinus (Burchell) fed differently heated soybean diets in concrete tanks. Four hundred and eighty male and female C. gariepinus (182 ± 10 g for females and 208 ± 5 g for males) were randomly distributed in groups into hapa nets. Iso‐nitrogenous (310 g kg^?1 crude protein) and iso‐caloric diets (355 Kcal kg^?1) prepared from raw soybean (D0) and soybean autoclaved for 5, 10, 15, 20, 25 and 30 min labelled D0, D5, D10, D15, D20, D25 and D30, were fed to the fish for 84 days. The fish meal based diet tagged DFM served as control. The male and female broodfish fed the fish‐meal‐based diet and diet D25 had significantly higher (P < 0.05) growth performance, gonad maturation, gonadosomatic index, relative fecundity and percentage egg fertilization and hatchability than the fish fed the other diets. The females had significantly higher (P < 0.05) weight increases and healthier condition over their male counterparts fed the same diets. This study showed that diet D25 was found to be the best substitute for fish meal that provided adequate nutrients required for the formation of genital products that produced strong offspring in C. gariepinus broodstock culture.     

Partial Replacement of Fish Meal by Fermented Soybean Meal in Diets for Black Sea Bream,Acanthopagrus schlegelii,Juveniles

The effect of fish meal (FM) substitution with fermented soybean meal (FSBM) in the diets of the carnivorous marine fish, black sea bream, Acanthopagrus schlegelii, was investigated. An 8‐wk feeding trial was conducted with black sea bream (11.82 ± 0.32 g; mean initial weight) in indoor flow‐through fiberglass tanks (25 fish per tank). Six isonitrogenous and isoenergetic diets were formulated, in which FM was replaced by FSBM at 0% (control diet), 10% (FSBM10), 20% (FSBM20), 30% (FSBM30), 40% (FSBM40), or 50% (FSBM50), respectively. Each diet was fed to triplicate groups of fish twice daily to apparent satiation. The results showed that there was no difference in survival of black sea bream during the feeding trial. Fish fed the FSBM10 or FSBM20 diet showed comparable growth performance compared with fish fed the control diet (P > 0.05), whereas more than 30% replacement of FM adversely affected weight gain and specific growth rate (P < 0.05). Feed intake was significantly lower for fish fed the FSBM50 diet compared with fish fed the control diet. Feed conversion ratio (FCR) tended to increase with increasing dietary FSBM with the poorest FCR observed for fish fed the FSBM50 diet. Protein efficiency ratio and protein productive values showed similar patterns. Apparent digestibility of nutrients significantly decreased with increasing dietary FSBM level. With the exception of protein content, no significant differences in whole body and dorsal muscle composition were observed in fish fed the various diets. Fish fed the FSBM50 diet had significantly lower intraperitoneal ratio than fish fed the control or FSBM10 diet. Hepatosomatic index and condition factor were unaffected by dietary treatments. This study showed that up to 20% of dietary FM protein could be replaced by FSBM protein in the diets of juvenile black sea bream.     

Evaluation of dietary yellow loess as an antibiotic replacer on growth,immune responses,serological characteristics and disease resistance in rainbow trout,Oncorhynchus mykiss

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 < 0.05). Lysozyme activity from fish fed YL₂₀ was detected to be significantly higher than that from fish fed CON diet (P < 0.05). While, superoxide dismutase (SOD) activity from fish fed YL₁₀ and YL₂₀ was recorded to be significantly higher than that from fish fed CON diet (P < 0.05). Fourteen days of challenge test with bacteria A. salmonicida showed significantly lower survival rate for CON than those of fish fed other experimental diets. Therefore, these results indicated that dietary yellow loess at 10–20 g kg^?1 could be a promising alternative of oxytetracycline in rainbow trout.     

Dietary Soy Peptide Enhances Thermotolerance and Survival of Juvenile Japanese Flounder,Paralichthys olivaceus

Soy peptide (SP), a soy protein enzymatic hydrolysate, contains bioactive substances that could be utilized as an immune‐stimulating feed ingredient. The experiment evaluated the efficacy of dietary SP on promoting growth, and enhancing tolerance and survival to heat stress in juvenile Japanese flounder, Paralichthys olivaceus. Four diets were incorporated with different levels of SP (0, 2, 5, and 10%) and a 6‐wk feeding trial ensued. Following the feeding trial, the experimental groups were subjected to heat stress to measure survival rate and heat shock protein 70s (HSP70s) in gill, liver, and skin. Fish fed diets with SP inclusion showed considerable decrease in percent weight gain. Significantly higher lethal time values to 50% mortality (LT₅₀) value were recorded for fish fed 10% SP. Moreover, LT₅₀ values of fish fed 2 and 5% SP were significantly higher compared with fish fed control diet. HSP70s produced in all the tissues were significantly highest in fish fed 10% SP. HSP70s values were significantly higher in fish fed 2 and 5% SP compared with fish fed control diet. A significant reduction in HSP70s among all groups during recovery period was also observed. These results suggest that SP can be used to enhance the immune response and survival of P. olivaceus under heat stress.     

Effects of Putative Growth or Health‐Enhancing Dietary Additives on Juvenile Olive Flounder,Paralichthys olivaceus,Performance

The effect on growth and body composition of various dietary additives with putative growth or health‐enhancing properties were determined in juvenile olive flounder (25 g initial weight). Nine experimental diets were prepared to contain one of the following additives: control (Con) with no additive, Opuntia ficus‐indica ver. saboten (OF), propolis (PP), lactic acid bacteria (LA), γ‐poly‐glutamic acid (PG), onion extract (OE), organic sulfur (OS), Biostone® (BS), and fig extract (FE). Fishmeal, dehulled soybean meal, and corn gluten were used as the protein source of the experimental diets. Wheat flour and soybean oil were used as the carbohydrate and lipid sources, respectively. Dietary additives were included in each experimental diet at 1% at the expense of wheat flour except for the FE (aqueous), which was substituted at 1% of the amount of water added to the diet. Fish were hand‐fed to satiation twice a day for 6 d/wk for 6 wk. Weight gain of fish fed the OE diet was higher than that of fish fed with the PP diet. Chemical composition of fish was not different among the experimental diets. OE was the most effective dietary additive to improve performance of olive flounder among additives used in this study.     

Dietary eicosapentaenoic acid requirement of juvenile rock bream,Oplegnathus fasciatus

A feeding trial was conducted to evaluate the optimum dietary level of eicosapentaenoic acid (EPA, 20:5n‐3) based on growth and non‐specific immune responses in juvenile rock bream. A basal diet without EPA supplementation was used as a control, and six other diets were prepared by supplementing with 4, 8, 12, 16, 20 or 40 g of EPA per kg diet. The actual EPA concentrations of the diets were 0.5, 4.3, 8.5, 13.0, 16.8, 21.0 and 41.2 g of EPA per kg diet, and the diets were abbreviated as EPA_0.5, EPA_4.3, EPA_8.5, EPA_13.0, EPA_16.8, EPA_21.0 and EPA_41.2, respectively. Triplicate groups of fish averaging 1.06 ± 0.01 g (mean ± SD) were fed one of the seven experimental diets at the apparent satiation for 8 weeks. At the end of the feeding trial, weight gain, specific growth rate and feed efficiency of fish fed EPA_16.8, EPA_21.0 and EPA_41.2 diets were significantly higher than those of fish fed EPA_0.5, EPA_4.3, EPA_8.5 and EPA_13.0 diets (p < .05). Superoxide dismutase activity of fish fed EPA_16.8, EPA_21.0 and EPA_41.2 diets were significantly higher than those of fish fed EPA_0.5, EPA_4.3 and EPA_8.5 diets. Fish fed EPA_21.0 and EPA_41.2 diets showed significantly higher lysozyme activity than did fish fed EPA_0.5, EPA_4.3, EPA_8.5 and EPA_13.0 diets. The broken‐line analysis of weight gain indicated that the optimum dietary EPA level was 16.7 g/kg diet. These results suggested that the optimum dietary EPA level in juvenile rock bream could be greater than 16.7 g/kg diet but less than or equal to 16.8 g/kg diet based on the broken‐line analysis and the ANOVA test of weight gain.