We evaluated the effects of long-term feeding of a fishmeal-free (FMF) diet on the growth parameters and physiological status, especially the bile acid status, of red sea bream (Pagrus major) yearlings. Two isonitrogenous and isolipidic diets were prepared; a fishmeal-based diet as the control, and an FMF diet containing soybean meal, corn gluten meal, soy protein concentrate, and pea protein concentrate as plant-derived ingredients, and poultry by-product meal and feather meal as animal-derived ingredients. Six hundred red sea bream yearlings were accommodated in six net cages, and the two experimental diets were hand-fed for 36 weeks. Throughout the 36-week trial, mean body weight and feed intake were significantly lower in the FMF group than in the control group. The concentrations of serum total cholesterol and high-density lipoprotein cholesterol were also significantly lower in the FMF group than in the control group throughout the trial. The total bile acid amount per fish was significantly lower in the FMF group than in the control group between Week 32 and 36 when the water temperature was the lowest (14.3–17.2 °C). Gene expression levels of hepatic cyp7a1 and cyp8b1 tended to be lower in the FMF group than in the control group from Week 20 to the end of the trial. Expression levels of hepatic sqle were higher in the FMF group than in the control group through the trial period and were markedly high at Week 36. Expression of hmgcr was also higher in the FMF group than in the control group at Week 32 and 36. The hindgut asbt expression of fish fed the FMF diet was lower than those fed the control diet at Week 28 and 32. These results suggest that the long-term feeding of an FMF diet to red sea bream yearlings causes reduced growth due to a significant reduction in feed intake and bile acid production, and enterohepatic circulation are strongly disturbed when water temperatures are low from autumn to winter.

Three experiments were performed to explore (i) the complete replacement of fish meal (FM) with a combination of fish residue meal (FRM, 65% round discarded fish + 35% byproduct), soy protein concentrate (SPC) from soymilk and corn gluten meal (CGM) in Trial 1 and (ii) the utilization of diets composed of increasing byproducts in FRM in the summer (Trial 2) and winter (Trial 3) seasons. In Trial 1, the ratio of (SPC + CGM):FM in the control diet (C) was 8:2. The FM component from diet C was replaced with FRM (diet, RM20), where the ratio of (SPC + CGM):FRM became 8:2, and this ratio was changed to 6:4, 4:6 and 2:8, and referred to as RM40, RM60 and RM80, respectively. In Trials 2 and 3, the ratios of round discarded fish and byproducts in FRM were adjusted to 65:35 (FRM1), 30:70 (FRM2) and 0:100 (FRM3), and the FRM component from diet RM40 in Trial 1 was replaced with FRM1, FRM2 and FRM3 to formulate diets RM1, RM2 and RM3, respectively. In Trials 1, 2 and 3, rearing periods were 10, 8 and 12 weeks, respectively. In Trials 1 and 3, there were no significant differences in growth parameters, nutrient retention efficiency or plasma constituents among the treatments, irrespective of the inclusion levels of FRM in the diets (p > 0.05). Although there were no significant differences in final mean weight (p > 0.05), daily feeding rate and feed conversion ratio in diet RM3 were significantly higher and lower, respectively, compared to the control group in Trial 2 (p < 0.05). These results suggest that FM can be entirely replaced with FRM, and that the total elimination of round discarded fish from FRM does not affect growth or health status in red sea bream either in summer or winter seasons.

Potato protein concentrate (PPC) is a potential fish meal (FM) substitute. We replaced FM in greater amberjack diets with low-temperature air-dried PPC (LT-PPC) and high-temperature rotary-dried PPC (HT-PPC) to investigate their effects on growth and feed utilization. Four experimental and one control diet was prepared. The control diet comprised FM, wherein the experimental diets were prepared by replacing 20 and 40% of FM in the control diet with LT-PPC (LP20 and LP40) or HT-PPC (LP20 and LP40). Following an 8-week growth trial, the final mean body weight, specific growth rate, and feed intake of HP40 diet-fed fish were significantly lower than those of control diet-fed fish (p < 0.05). However, these parameters in LT-PPC and HP20 diet-fed fish did not differ significantly from those of the control diet-fed fish (p> 0.05). In vitro relative protein digestibility did not differ between LT-PPC (91.1%) and HT-PPC (89.5%) (p > 0.05); however, the digestion speed of LT-PPC was higher (63.8%) than that of HT-PPC (46.8%) (p < 0.05). In conclusion, the findings demonstrate that LT-PPC and HT-PPC could be used to replace up to 40 and 20% of FM in greater amberjack diets, respectively, without compromising growth performance.

To reveal direct effects of various protein sources on digestive physiology of red seabream, Pagrus major (38.5 ± 0.4 g), six different protein sources of fishmeal (FM), soybean meal (SBM), corn gluten meal (CGM), soy protein concentrate (SPC), poultry by-product meal (PBM), and poultry-feather meal (PFM) were orally administered to fish (2 mg protein/g body weight) and sampled at 1.5 h and 3 h after administration. Gallbladder weight of fish administered FM, PBM, and PFM decreased after administration (p < 0.0001), while no difference was observed in the other ingredients compared to a non-protein sham control group, indicating that animal protein sources could more strongly stimulate bile secretion than plant protein sources in red seabream. Trypsin and chymotrypsin activity in the intestinal content markedly increased by the FM, SBM, and PFM administration (p < 0.0001). Lipase and amylase activity was also increased by FM and SBM but also by CGM for lipase and by PBM and PFM for amylase (p < 0.0001). These indicate that stimulation effect of the secretion of digestive enzymes is largely different among the protein sources. This might be due to the absorptive capacity of the protein source since intestinal absorption parameter genes (anpep, cpa, ggt1, and atp1a2) also increased by the FM, SBM, PBM or PFM (p < 0.05). In addition to the secretion levels of bile and digestive enzymes, gene expression levels of bile related genes (cyp7a1, cyp8b1, and shp) and digestion-regulating genes (casr and cck) were increased by the FM, SBM, PFM, and/or PBM administration, suggesting that animal proteins and SBM could be potent digestive stimulants compared to CGM and SPC. This study first revealed that single protein sources directly influence digestive enzyme secretion and bile secretion in fish. Information about the direct effect of each single source on digestive physiology could help to design feed formulation with less fishmeal.

We replaced fish meal (FM) with porcine blood meal (BM) in red sea bream (Pagrus major) diets to examine the influence on growth performance. Four experimental diets were prepared to be isonitrogenous and isolipidic by replacing 0%, 10%, 20% and 30% FM protein with BM (BM0, BM10, BM20 and BM30, respectively). After the 8-week feeding trial, the final mean body weight, weight gain, specific growth rate, daily feeding rate, condition factor and survival rate were not significantly different among the treatments (p > 0.05). However, feed efficiency tended to lower linearly as the dietary BM level increased, and no significant difference was observed between the BM20 and BM0 groups (p < 0.05). The protein digestibility in the BM20 and BM30 groups decreased significantly compared with that in the BM0 group (p < 0.05). Fat digestibility decreased significantly in the BM30 group than in other treatment groups (p < 0.05). The total serum protein and total cholesterol concentrations in the BM30 group were the highest among all treatment groups. In conclusion, BM can replace up to 20% of FM in the red sea bream diet without adversely affecting growth performance.

Fish meal (FM) used in fish farming is prepared by steaming, squeezing, defatting, drying and crushing raw fish material. However, how drying affects protein digestibility has not been systematically studied. Herein, we evaluate the effect of additional heating of FM on in vitro FM protein digestibility and growth performance of white trevally (Pseudocaranx dentex) juveniles. We heated conventional steam-dried Chilean FM from 50-200 degrees C for 1 h to prepare additionally heated FM (AHFM). In-vitro AHFM protein digestibility started to decrease significantly above 150 degrees C, along with substantial reduction in the protein digestion speed. Five isonitrogenous/isolipidic experimental diets were prepared by substituting different proportions of FM with AHFM produced by heating FM to 180 degrees C. In-vitro protein digestibility and digestion speed of the experimental diets decreased linearly with increasing AHFM content. After a 33-d feeding trial, the final bodyweight, specific growth rate, weight gain and feed efficiency of white trevallies decreased linearly and/or quadratically with increasing dietary AHFM levels. These findings indicate that in vitro protein digestibility of AHFM decreases linearly at temperatures above 150 degrees C, and the growth and feed efficiency of white trevallies are negatively affected by dietary inclusion of AHFM processed at 180 degrees C.

Black soldier fly meal (BM) is an outstanding candidate as a fish meal (FM) substitute because it contains relatively high protein and essential amino acids. In this study, we replaced FM in red sea bream diets (Pagrus major) with BM to investigate its effect on growth and feed utilization. Six isonitrogenous and isolipidic experimental diets were prepared by substituting 0%, 20%, 40%, 60%, 80% and 100% FM protein with BM (Control, BM20, BM40, BM60, BM80 and BM100, respectively). After the 8-week feeding trial, final body weight, weight gain, specific growth rate and feed efficiency decreased linearly with increasing dietary BM level (p < 0.05). Apparent digestibility of protein and fat and serum total cholesterol concentration decreased with increasing dietary BM levels (p < 0.05) Final body weight, WG, SGR and FE against dietary BM level had breaking points of 76.2%, 41.7%, 76.5% and 60.0%, respectively, in segmental regression analysis. In conclusion, the results suggest that BM can replace a maximum of 41.7% of FM in the diet of red sea bream without compromising growth performance or feed efficiency for 56 days.

The optimum level of fishmeal (FM) protein replacement by bacterial protein meal (BPM) was determined in the diet of juvenile red sea bream, Pagrus major. Six isoproteic and isolipidic diets were formulated to replace 0 (control diet), 190, 280, 370, 470 and 560 g of the FM protein kg-1 diet with BPM protein, and referred to as C, BP19, BP28, BP37, BP47 and BP56, respectively. Each diet was fed to triplicate groups of twenty fish (mean weight ~43 g) twice per day to apparent satiation. Fish fed diets C and BP19 did not show significant differences (p >.05) in growth, apparent digestibility or protein and lipid retention efficiency, but the daily feeding rate (DFR) was significantly lower under BP19 than under C. However, almost all growth parameters were significantly reduced when FM protein replacement with BPM was further increased from 280 to 560 g kg-1 diet (p <.05). The results of polynomial regression analysis (second-order) revealed significant negative correlations between dietary copper levels and final mean weight (R2 =.913), specific growth rate (R2 =.913) and DFR (R2 =.956). The results indicated that BPM could replace approximately 190 g of FM protein kg-1 diet in the juvenile red sea bream diet without compromising growth performance or feed efficiency.

Two trials were carried out to determine the optimal replacement level of fish meal (FM) protein by the bacterial protein meal FeedKind (R) (FK), in the diet of juvenile Japanese yellowtail, Seriola quinqueradiata. FK protein was produced from the methanotrophic bacteria Methylococcus capsulatus Bath, which utilizes methane as its sole carbon and energy source. In Trial 1, six diets were formulated: control diet (C) with FM as protein source; four experimental diets in which the FM of diet C was replaced at 25 (FK25), 50 (FK50), 75 (FK75) and 100% (FK100) by FK; and a final experimental diet in which 3% of FK in diet FK100 was replaced by enzyme-treated FM (EFK). In Trial 2, seven diets were prepared: control diet C similar to Trial 1; three experimental diets in which the FM of diet C was replaced at 20 (FK20), 25 (FK25) and 30% (FK30) by FK; two experimental diets in which FK from diet FK25 was replaced either by further grinding FK (FK25J) or lower digestible FK (FK25L); and experimental diet EFK in which 3% of the FK in diet FK25 was replaced by enzyme-treated FM. Fifteen (ca. 126g) or ten fish (ca. 80 g) were stocked into each of eighteen 500 L tanks in triplicates in Trial 1 and 2, respectively, fed two times daily until apparent satiation, and cultured for 8 weeks. At the end of both trials, feces were collected after feeding with chromic oxide (Cr2O3) mixed diets. In Trial 1, all growth parameters and nutrients retention efficiencies showed similar patterns and no significant differences were observed between diets C and FK25 (P > .05), though feed efficiency (FE) was reduced by 10% in the latter diet. However, other diets showed significantly lower growth performance compared to diet C (P < .05). When different lots of FK was used and feed formula was slightly adjusted in Trial 2, there were no significant differences in the growth performance, nutrients digestibility and retention efficiency, among the treatments even up to 30% FM protein replacement (P > .05). FE was also either equal to or higher in all FK-based diets compared with control group. Overall, results indicated that the FK can comprise up to 20% of total diet, replacing 30% of the FM protein in diet for yellowtail, without compromising growth performance or FE.

© 2019 John Wiley & Sons Ltd Potato protein concentrate (PPC) is a promising candidate as a fish meal (FM) substitute because it has high protein and essential amino acid content. In the present study, we replaced FM in greater amberjack diets with PPC to investigate the effect on growth and feed utilization. Four isonitrogenous, isolipidic and isocaloric experimental diets were prepared by substituting 0, 20, 40 and 60% of FM protein with PPC (Control, P20, P40 and P60 respectively). The in vitro protein digestibility of protein in PPC was 88.8%, relative to 100% protein in the FM. The in vitro protein digestibility of protein in the experimental diets also decreased with increasing PPC and was lowest at 84.2% in P60. After the 7-week feeding trial, final body weight, weight gain and thermal growth coefficient tended to decrease with increasing PPC and were significantly lower in P60 than in the control (p <.05). Further, fish fed with diets P40 and P60 showed significantly lower feed conversion and protein efficiency ratios than the control group (p <.05). In conclusion, the results suggest that PPC can replace up to 20% of FM in the diet of greater amberjack without compromising the growth performance or feed efficiency.

Understanding fish nutritional requirements is critical for developing aquaculture feeds. We evaluated the effects of dietary digestible protein (DP) and digestible energy (DE) levels and the DP/DE ratio on growth of yearling greater amberjack Seriola dumerili at suboptimal temperatures (20.1–24.5°C). A 3×3 factorial design with duplication was used. Nine experimental diets were formulated, containing three levels of crude protein (CP; 450, 510, and 560 g/kg) and three levels of crude lipid (CL; 130, 180, and 230 g/kg). Eighteen tanks of greater amberjack (mean initial weight 277.4 g) were fed each experimental diet (1.3% BW/day) for 40 days. Feed efficiency improved significantly with increasing dietary CP up to 510 g/kg and with dietary CL up to 180 g/kg. Specific growth rate and protein efficiency ratio improved significantly with increasing dietary CL up to 180 g/kg. Whole body and liver crude fat levels increased with increasing dietary CL up to 180 g/kg. No significant difference was shown in protein and fat retention. High growth rate and feed efficiency were observed in fish fed the 510/180 diet containing 387 g/kg DP and 15.9 MJ/kg DE (24.4 g/MJ DP/DE), which we therefore consider optimal for growth and feed utilization of yearling greater amberjack.

© 2019, Japanese Society of Fisheries Science. Greater amberjack is a popular aquaculture species, but its nutritional requirements remain poorly understood. The present study aimed to identify feeding stimulants for greater amberjack from a synthetic extract (SE) of jack mackerel muscle. A bioassay involving a semi-purified casein diet supplemented with feeding stimulant candidates was performed. The SE was composed of amino acids, nucleotides, and other compounds. Relative feed intake (RFI) in the SE treatment was similar to that in the natural extract treatment. The all-nucleotide treatment [inosine monophosphate (IMP), inosine, adenosine monophosphate (AMP), adenosine diphosphate (ADP), and adenosine triphosphate (ATP)] showed a comparable RFI to that of the SE treatment. Furthermore, the RFI did not decrease when amino acids and other compounds were omitted from the SE, but significantly decreased when nucleotides were removed from the SE. Exclusion of inosine, AMP, ADP, and ATP had no effect on the RFI. Among nucleotides, only IMP supplementation showed a comparable RFI to that in the SE and all-nucleotide treatments. Even without IMP, RFI increased with increasing concentrations of nucleotides and their combined application (especially inosine + ADP). These results indicate that the feeding stimulatory effect of jack mackerel muscle extract on greater amberjack depended mainly on IMP.

© 2018 Japanese Society for Aquaculture Research, Nishimura Toushadou Ltd.. All rights reserved. A noninvasive assay for estimating stomach evacuation velocity and daily meal frequency for a commercially available artificial diet was evaluated using Pacific bluefin tuna fingerlings. This was attributed to the hypothesis that fish could consume a diet until filling up a gap of the stomach after a feeding until satiation. Consecutive feeding frequencies of 4, 11 and 3 meals daily from 7: 00 to 17: 00 for 5 days each, were conducted on a single group of 1,200 fingerlings, weighing 70-190 g in a net cage. The daily feed intake linearly increased with passing the feeding protocols. For each daily feeding event, ô daily feed intake of a first meal was higher than those of second meals onward in a day. The stomach evacuation velocity expressed as a slope, subtracting accumulative ô daily feed intake of a second meal onward from that of a first meal, was y =-6.94x + 29.6, y =-7.08x + 31.2 and y =-7.07x + 44.4 for 4, 11 and 3 meals daily, respectively. These results indicate that the stomach evacuation velocity of the fingerlings was estimated to be around 7ô daily feed intake per hour, and daily meal frequency was 3 or 4 until apparent satiety was achieved with the artificial diet.

To improve the commercial value of cultured yellowtail, the following two experiments were conducted. In the first experiment, the anti-oxidant effects of yuzu Citrus junos juice on prevention of dark muscle discoloration during storage in yellowtail Seriola quinqueradiata were investigated. Yellowtails were fed one of four diets supplemented with yuzu juice (0, 12.5, 25 and 50 mL/kg diets) for 40 days. Growth performance was not significantly different among the dietary groups. Dark muscle discoloration was reduced in fish fed yuzu juice-supplemented diets during storage at 4°C. These results indicate that yuzu juice-supplemented diets prevent dark muscle discoloration without affecting the growth of young yellowtail after 40 days of feeding. In the second experiment, the accumulation of yuzu flavor components in fish meat was confirmed; the fish meat had a delicate yuzu flavor after the first experiment. The five yuzu flavor components were detected and identified in the meat from fish fed a yuzu juice-supplemented diet for a month. This indicates that some yuzu flavor components were transferred from the yuzu juice-supplemented diet to fish meat.

A growth trial was conducted to evaluate the effect of dietary lipid level on juvenile kelp grouper Epinephelus bruneus. Juvenile kelp grouper were fed isonitrogenous diets (470 g/kg crude protein) with four levels of crude lipid at 60 g/kg (CL60), 130 g/kg (CL130), 210 g/kg (CL210), and 270 g/kg (CL270) for 56 days. The highest growth performance and feed utilization were found in the CL130 diet group. A high dietary lipid level (CL270 diet) significantly decreased growth performance and feed utilization. A significant difference in apparent digestibility was only observed in protein, which was highest in the CL130 diet groups. The highest retention for protein, energy, and lipid was found in the CL130 diet group. The dietary lipid levels significantly changed whole-body and liver compositions, the highest being the CL60 diet group for crude protein level and the CL210 diet group for crude lipid level. Based on a second-order polynomial regression analysis of crude lipid level against specific growth rate and protein efficiency ratio, the optimum dietary lipid level for kelp grouper was estimated to be 152 and 154 g/kg diet, respectively. © The Japanese Society of Fisheries Science 2009.

Dietary fish oil (FO) was replaced by olive oil (OO) in young yellowtail Seriola quinqueradiata to investigate its effects on growth, muscular fatty acid composition and prevention of color deterioration of dark muscle during storage. Yellowtail were fed one of four diets, where FO (80 g/kg diet) was replaced by OO (0, 25, 50 and 100%) for 40 days. No significant difference in growth was seen among the diet groups. In addition, these experimental diets did not affect the proximate compositions of the dorsal muscle, ventral muscle and the liver in these fish. Serum total protein, glucose and total cholesterol levels did not show significant differences; however, serum triglyceride levels were significantly higher in fish fed 50 and 100% OO diets. Fatty acid composition of ventral muscle reflected the composition of the respective diets. Dark muscle discoloration was reduced in fish fed OO diets after 12 to 18 h during storage at 4°C. Furthermore, the redness value of fresh dark muscle increased depending on the extent of FO replacement. These results indicate that the partial or total dietary replacement of FO with OO prevents discoloration of dark muscle without affecting the growth of young yellowtail after 40 days of feeding. © 2008 Japanese Society of Fisheries Science.

Feeding stimulants for the common japanese goby Acanthogobius flavimanus were examined by omission test using the synthetic krill Euphausia pacifica extract, based on a daily feeding of casein diet with various test solution. The complete synthetic extract of krill possessed a remarkable feeding stimulant activity. Subdivision of the synthetic extract showed that the group of neutral amino acids plus nucleotides was highly active. However, the individual amino acids, nucleotides and other bases groups as well as the groups of amino acids plus other bases and nucleotides plus other bases were inherently lower active. Therefore, the feeding stimulant activity of synthetic extract of krill for the fish was considered to be due to the synergistic effect of neutral amino acids plus nucleotides.

A study was conducted to determine optimum dietary digestible protein (DP) and digestible energy (DE) levels and DP DE-1 ratio for growth of greater amberjack Seriola dumerili fingerlings. A 3 x 3 factorial design with duplication was used in this study. Nine experimental diets were formulated to contain three levels of crude protein (CP; 420, 470 and 530 g kg-1) and three levels of crude lipid (CL; 130, 180 and 230 g kg-1). Nine groups of fingerling (initial weight 51.8 g) were fed each experimental diet for 40 days. Final body weight, feed efficiency, specific growth rate and energy efficiency were significantly affected by dietary protein and lipid level. These parameters tended to improve with increasing dietary protein level. Conversely, an increase of lipid level negatively affected these parameters. High growth rate and feed efficiency were obtained from fish fed the diet containing 393 g kg-1 DP and 14.2 MJ kg-1 DE (27.7 g MJ-1 DP DE-1). The high DP DE-1 (27.7 g MJ-1) indicates that greater amberjack fingerling are highly dependent on dietary protein as an energy source. © 2006 Blackwell Publishing Ltd.

Feeding study was conducted to investigate the availability of poultry by-product meal (PBM) as an alternative protein source for fish meal (FM) and the effect of amino acid supplementation in greater amberjack diet. FM was used as a main protein source in control diet and was replaced with PBM at levels of 20, 40 and 60% to be almost isonitrogenously and isoenergetically. Each replacement level was examined with or without essential amino acids (L-lysine, L-methionine, L-leucine and L-isoleucine) supplementation. Seven groups of greater amberjack (initial body weight 93.0 g) were fed each diet for 50 days. In the without amino acids supplementation groups, growth and feed efficiency of fish fed diets with more than 40% replacement were significantly lower than those of fish fed control diet. In the amino acids supplementation groups, growth and feed efficiency of fish fed diet with 20 and 40% replacement levels were comparable to fish fed control diet. These results indicate that FM can be replaced by PBM for greater amberjack diet up to 40% with supplementation of essential amino acids.