Interactive effects of dietary cholesterol and protein sources on growth performance and cholesterol metabolism of Japanese flounder (Paralichthys olivaceus)

A feeding trial was conducted to compare the effects of supplemental cholesterol in fish meal (FM), fish protein concentrate (FPC), soy protein isolate (SPI) and soy protein concentrate (SPC)‐based diets on growth performance and plasma lipoprotein levels of Japanese flounder (Paralichthys olivaceus). Eight isonitrogenous and isocaloric diets including FM, FPC, SPI or SPC as sole protein source with or without supplementation with 10 g cholesterol kg^?1 diet were fed to juvenile fish for 8 weeks. Dietary cholesterol supplementation significantly increased the feed intake and specific growth rate in fish fed SPI‐based diets, but decreased those in fish fed FPC‐based diets. In addition, cholesterol supplementation significantly increased the level of cholesterol and ratio of low‐density lipoprotein cholesterol to high‐density lipoprotein cholesterol in plasma of fish fed fish protein‐based diets, whereas no effects were observed in fish fed soy protein‐based diets. The hepatic lipid content of fish fed FPC‐, SPI‐ or SPC‐based diets were significantly increased by supplemental cholesterol, but no influence was observed in fish fed FM‐based diets. These results suggested that dietary protein source modify the growth‐stimulating action of cholesterol; cholesterol supplementation may increase the arteriosclerotic lesion in fish fed fish protein‐based diets and the incidence of fatty liver in fish fed soy protein‐based diets.     

Alternative protein sources in diets for Japanese flounder Paralichthys olivaceus (Temminck and Schlegel): II. Effects on nutrient digestibility and digestive enzyme activity

An 8‐week feeding trial was conducted to compare the effects of dietary protein sources on nutrient digestibility and digestive enzyme activity. Four experimental diets were formulated to contain one of the following as the sole protein source: fish meal (FM), fish protein concentrate (FPC), soy protein concentrate (SPC) and soy protein isolate (SPI). Each diet was randomly assigned to triplicate aquaria stocked with 25 Japanese flounder (Paralichthys olivaceus) each. The dry matter, crude protein and energy digestibility and individual amino acid availability of the SPC‐based diet were significantly lower than those of the other diets. The crude lipid digestibility of soy protein‐based diets was significantly lower than that of the FM‐based diet. The pepsin/protease activity was significantly higher in fish fed fish protein‐based diets compared with fish fed soy protein‐based diets. The lipase activity in fish fed the SPI‐based diet was the highest among the dietary treatments. These results indicate that P. olivaceus can effectively digest the protein from FPC and SPI (but not SPC) as well as FM. The low protein digestibility and amino acid availability of the SPC‐based diet may be related to the non‐protein compounds present in SPC, whereas the low‐lipid digestibility of soy protein‐based diets may contribute to the undigested soy protein fractions and/or the alcohol‐soluble components.     

Effects of natural feeding stimulants and glutamic acid supplementation on the feed intake,growth performance and digestive enzyme activities of red sea bream (Pagrus major) fed fish meal‐free soy protein concentrate (SPC)‐based diet

Two experiments were conducted for red sea bream (Pagrus major). In experiment 1, the optimum level of glutamic acid and natural feeding stimulants to enhance feed intake were determined and found that glutamic acid level of 0.5% and fish meat hydrolysate (FMH) were effective. In experiment 2, fish were fed with soy protein concentrate (SPC)‐based diet with synthetic feeding stimulants (Basal diet), the Basal diet with FMH (FMH diet), the FMH diet with glutamic acid (FMHG diet) and with fish meal diet (FM diet) as a control until satiation for 8 weeks. Feed intake of FMHG‐fed fish was significantly higher than others (p < 0.05). Specific growth rate and the feed conversion ratio of FMHG were comparable to those of FM‐fed fish (p > 0.05). Relative visceral fat ratio and crude lipid content of any SPC‐based diet‐fed fish tended to be lower than those of FM diet‐fed fish. There were no significant differences in trypsin and lipase activities hepatopancreas among treatments. SPC can be utilized as a sole protein source in a diet for red sea bream. The lower growth performance in SPC‐based diet‐ fed fish was not due to poor digestive enzyme secretion but could be associated with lipid utilization disorder.     

Growth, uptake and retention of nitrogen and phosphorus, and absorption of other minerals in Atlantic salmon Salmo salar fed diets with fish meal and soy–protein concentrate as the main sources of protein

An experiment with 0.2‐kg Atlantic salmon, Salmo salar in saltwater was conducted to determine if the fish could grow normally, and maintain normal nitrogen (N) and mineral balance when fed a diet with the majority of the protein (75%) derived from soy‐protein concentrate (SPC). The two diets contained 50% SPC and 15% fish meal (FM) or 60% FM as the sources of protein. No calcium phosphate was added to the diets in order to assess the availability of P from the ingredients. A second aim was to investigate if whole‐body concentrations of essential elements and growth were related in individual salmon. Growth (SGR=0.88–0.89) was similar in salmon fed the two diets, and the fish nearly doubled their body weights during the 84 days of feeding. Feed conversion was more efficient for the FM diet (0.81 kg intake kg^?1 gain) than for the SPC diet (0.89 kg kg^?1). The intake of N was similar, faecal loss of N was lower, while the metabolic N excretion was greater in the fish fed the FM than the SPC diet. This resulted in a total excretion of 35.4 g N kg^?1 gain for the salmon fed the FM diet and 35.5 g N for the fish fed the SPC diet. Both the intake, faecal and metabolic excretion of P were higher in the fish fed the FM diet than the SPC diet, resulting in a total excretion of 10.5 g P kg^?1 gain for the FM diet and 7.2 g P for the SPC diet. Whole‐body concentrations of Ca, Mg, P and Zn were lower in the fish fed the SPC diet, while the Ca–P ratio was decreased, both when compared with the fish at the start of the experiment, and the fish fed the FM diet. The differences in elemental composition were ascribed to a combination of reduced availability of elements due to phytic acid and lower concentration of elements in the SPC than in the FM. No reduction in growth of individual fish, which could be ascribed to reduced availability of essential elements, was seen.     

Supplementation of Protein Hydrolysates to a Low‐fishmeal Diet Improves Growth and Health Status of Juvenile Olive Flounder,Paralichthys olivaceus

An 11‐wk feeding trial was conducted to evaluate three different protein hydrolysates as feed ingredients in high‐plant‐protein diets for juvenile olive flounder. Five experimental diets were fed to juvenile olive flounder to examine the effect of three different protein hydrolysates on growth performance, innate immunity, and disease resistance against bacterial infection. A basal fishmeal (FM)‐based diet was regarded as a high‐FM diet (HFM) and a diet containing soy protein concentrate (SPC) as a substitute for 50% FM protein was considered as a low‐FM diet (LFM). Three other diets contained three different sources of protein hydrolysates, including shrimp, tilapia, and krill hydrolysates (designated as SH, TH, and KH), replacing 12% of FM protein. All diets were formulated to be isonitrogenous and isocaloric. Triplicate groups of fish (15.1 ± 0.1 g) were handfed one of the diets to apparent satiation twice daily for 11 wk and subsequently challenged against Edwardsiella tarda. Growth performance and feed utilization of fish fed hydrolysate‐supplemented diets were significantly improved compared to those of fish fed the LFM diet. Dietary inclusion of the protein hydrolysates significantly enhanced apparent digestibility of dry matter and protein of the diets. In the proximal intestine, histological alterations were observed in the fish fed the LFM diet. The fish fed the hydrolysate diets showed significantly longer mucosal fold and enterocytes and greater number of goblet cells compared to fish fed the LFM diet. Respiratory burst activity was significantly higher in fish fed the TH and KH diets than fish fed the LFM diet. Significantly higher immunoglobulin levels were found in fish fed SH and KH diets compared to those of fish fed the LFM diet. Dietary inclusion of the protein hydrolysates in SPC‐based diets exhibited the highest lysozyme activity. Significantly higher superoxide activity was observed in groups of fish fed the KH diet. Fish offered the protein hydrolysates were more resistant to bacterial infection caused by E. tarda. The results of this study suggest that the tested protein hydrolysates can be used as potential dietary supplements to improve growth performance and health status of juvenile olive flounder when they were fed a LFM diet.     

Growth and feeding responses of the mutton snapper,Lutjanus analis (Cuvier 1828), fed on diets with soy protein concentrate in replacement of Anchovy fish meal

This study evaluated the growth (first phase) and feeding responses (second phase) of juvenile mutton snapper fed four isonitrogenous and isoenergetic diets with increasing levels of soy protein concentrate (SPC) in substitution to fish meal (FM). The FM was replaced by SPC at 0% (basal diet, SPC000), 33% (SPC130), 57% (SPC214) and 77% (SPC300). After 95 days of rearing, fish fed SPC300 attained a significantly lower body weight (54.9 ± 13.2 g) compared with those fed diets SPC000, SPC130 and SPC214 (76.5 ± 14.0 g, 73.9 ± 13.8 g and 70.5 ± 14.0 g respectively). Fish yield increased significantly from 891 ± 36 g m^?3 for fish fed SPC300 to an average of 1099 ± 111 g m^?3 for other diets. A maximum fish body weight gain of 0.60 ± 0.05 g day^?1 and a maximum specific growth rate of 1.47 ± 0.07% day^?1 were achieved for SPC000. Behavioural assays conducted during 10 days revealed the loss in fish growth with diets containing higher levels of SPC was due to a decline in feed intake. Low feed intake driven by a poor feed palatability appeared to have been a major obstacle against higher inputs of SPC in diets for mutton snapper.     

Evaluation of shrimp or tilapia protein hydrolysate at graded dosages in low fish meal diet for olive flounder (Paralichthys olivaceus)

A study was carried out to examine and optimize the inclusion levels of shrimp hydrolysate (SH) or tilapia hydrolysate (TH) in low fishmeal diets for olive flounder (Paralichthys olivaceus). A fishmeal (FM)‐based diet was considered as a high FM (HFM) diet, and a diet containing soy protein concentrate (SPC) as a FM replacer at 50% substitution level was regarded as a low FM (LFM) diet. Six other experimental diets were prepared by dietary supplementation of SH or TH to LFM diet at different inclusion levels of 15 g/kg, 30 or 45 g/kg in the expense of FM (designated as SH‐1.5, SH‐3.0, SH‐4.5, TH‐1.5, TH‐3.0 and TH‐4.5, respectively). After 10 weeks of a feeding trial, growth performance and feed utilization efficiency of fish were significantly higher in fish fed HFM, SH‐3.0, SH‐4.5, TH‐1.5 and TH‐3.0 diets compared to those of fish fed LFM diet. Intestine diameter, villus height and goblet cell counts of fish were significantly increased by dietary inclusion of SH or TH into LFM diet. Dry matter and protein digestibility of diets were significantly improved by SH or TH incorporation. Innate immunity of fish was significantly enhanced by dietary SH or TH supplementation into LFM diet. Disease resistance of fish was significantly increased against Edwardsiella tarda by dietary inclusion of SH and TH at the highest inclusion level (45 g/kg). The optimum inclusion level of SH or TH in a SPC‐based LFM diet could be ~30 g/kg and 15–30 g/kg, for olive flounder.     

Fishmeal can be completely replaced by soy protein concentrate by increasing feeding frequency in Nile tilapia (Oreochromis niloticus GIFT strain) less than 2 g

An 8‐week growth trial was conducted to determine the effects of complete replacement of fishmeal protein by soy protein concentrate (SPC) on growth performance of Nile tilapia (Oreochromis niloticus GIFT strain) fry (initial body weight 1.6 ± 0.0 g). In control diet, 135 g kg^‐1 fishmeal was used, and in the other two diets, 100% of fishmeal was replaced by SPC supplemented with or without methionine hydroxy analogue (MHA) according to the content in FM diet. Fish of FM group were fed twice daily. Fish of SPC6 group were fed SPC diet six times daily. Fish of SPCM group were fed twice (SPCM2) or six times (SPCM6) daily. The results showed that complete replacement of fishmeal with SPC did not affect survival, condition factor, visceralsomatic index of Nile tilapia. Feed intake (FI) and feed conversion ratio (FCR) of fish in SPCM2 and SPC6 groups were higher than those in FM and SPCM6 groups. Specific growth rate (SGR) of fish in SPCM6 group was highest among four treatments. Productive protein value (PPV) of SPCM2 and SPC6 groups were significantly lower than that of FM group. Fishmeal could be completely replaced by SPC without negative effect on growth by MHA supplementation and increasing feeding frequency.     

Dietary substitution of fishmeal by alternative protein with guanosine monophosphate supplementation influences growth,digestibility, blood chemistry profile,immunity, and stress resistance of red sea bream, <Emphasis Type="Italic">Pagrus major</Emphasis>

We determined the effects of complete fishmeal (FM) replacement by alternative protein (soy protein concentrate, SPC) with guanosine monophosphate (GMP) supplementation on growth, digestibility, immunity, blood chemistry profile, and stress resistance of juvenile red sea bream, Pagrus major. FM protein of a FM-based control diet (FM0) was replaced with 33.3 (FM33.3), 66.6 (FM66.7), and 100% (FM100) by SPC protein, and each replacement group was supplemented with 0.4% GMP to formulate four experimental diets. Each diet was randomly allocated to triplicate groups of fish (4.8 g) for 56 days. Results demonstrated that fish fed diet group FM33.3 had the significantly highest final weight, weight gain-specific growth rate, and feed intake. Meanwhile, in comparison to control, growth performance and feed utilization did not significantly differ with 66.7% FM replacement by SPC with GMP supplementation. Apparent digestibility coefficient of protein and lipid also followed a similar trend. All growth, feed utilization, and digestibility parameters were significantly lower in FM100 diet group. Blood urea nitrogen (BUN) and triglycerides (TG) increased (P < 0.05) with increasing FM replacement level by SPC. Interestingly, total cholesterol level reduces with the increasing level of FM replacement by SPC with GMP supplementation. Fish fed FM0 diet group showed the best condition of both oxidative and freshwater stress resistance. Meanwhile, FM33.3 and FM66.7 diet groups showed acceptable conditions. Innate immune responses enhanced with the increasing FM replacement level by SPC with GMP supplementation. In conclusion, FM could be replaced ≤66.7% by SPC with GMP supplementation in diets for red sea bream without any adverse effects on fish performances.     

Effects of replacing fish meal with soya protein concentrate on growth,feed efficiency and digestibility in diets for snakehead,Channa striata

Soya bean meal‐based formulated feeds have recently become available for snakehead culture in Vietnam. This study was conducted to determine the appropriate replacement of fish meal (FM) protein by another soya product, soya protein concentrate (SPC), in snakehead (Channa striata) diets. Five iso‐nitrogenous (45% crude protein) and iso‐caloric (19 KJ g^?1) practical diets were formulated to replace 0% (control), 40%, 60%, 80% and 100% of protein FM by protein SPC (100% FM, 40% SPC, 60% SPC, 80% SPC and 100% SPC respectively). A digestibility experiment was also conducted with the same formulated diets with addition of 1% chromic oxide. Fish fed 100% FM and 40% SPC diets had significantly better growth and survival compared with other treatments. Feed intake, feed conversion ratio, protein efficiency ratio and net protein utilization, trypsin and chymotrypsin activities of experimental fish fed 100% FM and 40% SPC diets were significantly higher than those fed other diets. The apparent digestibility coefficient (ADC) of the diet and diet components, ADC_diet, ADC_protein and ADC_lipid, of fish fed diet 40% SPC and 100% FM treatment were significantly higher than those of other treatments. The cost/kg fish produced in diets 100% FM and 40% SPC was much lower compared with other treatments. Dietary inclusion levels of SPC in diet above 40% significantly affected fish survival, growth, digestibility and trypsin and chymotrypsin activities, although fish chemical composition was not greatly affected.     

Hydrolysed fish protein concentrate (FPC) reduces viscera mass in Atlantic salmon (Salmo salar) fed plant‐protein‐based diets

Atlantic salmon fed diets devoid of fishmeal but added 0.5 g  kg^?1 fish protein concentrate (FPC) showed reduced growth and lipid deposition without affecting protein accretion as compared to fish fed a fishmeal‐based control diet. The aim of the current study was to assess whether higher inclusion of FPC improved the growth and lipid deposition of Atlantic salmon (initial body weight 380 g) fed high plant protein diets. Quadruplicate groups of fish were fed diets containing 200 g kg^?1 fishmeal of which was replaced with FPC (150, 112, 75, 38 and 0 g kg^?1) for a period of 79 days. The rest of the diet protein was a mixture of plant proteins. The lipid source used was fish oil. A fishmeal‐based diet was included as a positive control for growth performance. None of the test diets differed from the positive control‐fed fish in voluntary feed intake, growth performance or nutrient accretion. Thus, the test diets were found appropriate to assess the effect of FPC inclusion. Replacement of fishmeal with increasing concentration of FPC did not affect voluntary feed intake (P = 0.56), but growth performance decreased (P = 0.02) resulting in an increased feed conversion ratio (P = 0.003). Viscerosomatic index decreased as diet FPC inclusion increased (P = 0.012) without affecting the dress out weight (P = 0.08). Thus, the apparently improved growth in fish fed the diets with the low FPC inclusion was because of a higher visceral mass. Possible reasons for the reduced visceral mass following addition of FPC to high plant protein diets are discussed.     

Fish meal replacement by soy protein from soymilk in the diets of red sea bream (Pagrus major)

Six isoenergetic diets were formulated as follows: fish meal (FM) 700 g kg^–1 (control, C), FM 300 g kg^–1 + soy protein concentrate 300 g kg^–1 (SPC), FM 300 g kg^–1 + enzyme‐treated SPC 300 g kg^–1 (ESC), FM 170 g kg^–1 + soy protein isolate 300 g kg^–1 (SPI), FM 160 g kg^–1 + enzyme‐treated SPI 300 g kg^–1 (ESI) and FM 150 g kg^–1 + conglycinin 300 g kg^–1(CG). Forty fish (3.9 g) were randomly distributed into each of eighteen 300‐L tanks, fed twice daily until satiation for 8 weeks. The final body weight, specific growth rate and condition factor did not show significant differences among the fish fed with diets C, SPC, ESC and ESI (p > .05). The survival was significantly lower in fish fed with diets SPI and CG. Feed efficiency was significantly higher in fish fed with diets SPC and C than in fish fed with other diets (p < .05). There were no significant differences in nutrients retention efficiencies in fish fed with diets C, SPC, ESC and ESI. A significantly higher phosphorus retention efficiency in fish fed with soymilk protein diets resulted in lower phosphorus discharge to the environment (p < .05). These results suggest that the soymilk proteins can comfortably replace 570–770 g FM kg^–1 diet of red sea bream juvenile, which will ensure significant ecological benefits through reducing phosphorus load to the environment.     

Effect of dietary replacement of fish meal by soybean protein concentrate on growth performance and phosphorus discharging of juvenile black sea bream,Acanthopagrus schlegelii

The 8‐week experiment was conducted to evaluate the effects of partial replacement of fish meal (FM) with soybean protein concentrate (SPC) on juvenile black sea bream, Acanthopagrus schlegelii (10.70 ± 0.04 g). Diets were formulated to replace FM protein by SPC at 0, 8, 16, 24, 32 or 40% (designated as T1, T2, T3, T4, T5 and T6, respectively). Diets except T1 were supplemented with phytase at 2000 phytase activity U kg^?1. The results showed that survival rate, growth performance and feed utilization were not significantly affected by increasing dietary SPC. Fish fed diet T3 had higher feed intake compared to those fed T1, T2 and T5 diets. Whole body compositions of black sea bream were significantly influenced by SPC replacing FM except for protein, ash and phosphorus content. Condition factor of fish was significantly lower in T2 than that of fish in T3 group. Apparent digestibility coefficients (ADCs) of dry matter was higher in fish fed T6 diet than those of fish fed T1 and T2 diets, ADCs of phosphorus increased with dietary SPC level up to T3 and then decreased. The results obtained in this study indicate that FM protein could be effectively replaced by SPC protein with phytase in diet of black sea bream.     

大豆浓缩蛋白替代鱼粉对大菱鲆摄食、生长及体组成的影响

研究了大豆浓缩蛋白(SPC)替代鱼粉对大菱鲆生长及生理生化指标的影响。5种饲料分别含有0、12.0%、25.0%、37.0%和49.5%的SPC以替代相应的鱼粉,并分别添加0、0.83%、1.65%、2.48%和3.30%的必需氨基酸混合物(L-lysine∶DL-methionine∶L-leucine∶Lvaline∶L-threonine=18∶6∶3∶2.5∶2)以平衡各组饲料的氨基酸组成。每种饲料投喂3个水族箱(300 L),每个水族箱放养实验鱼16尾,实验鱼初始体质量为(31.1±0.1)g。经过9周生长实验,结果显示随着饲料中SPC替代水平的升高,大菱鲆摄食率、特定生长率均显著下降(P0.001)。然而,当使用0~37.0%的SPC替代鱼粉时,各处理组饲料效率和蛋白质效率未出现显著差异(P0.05)。饲料中SPC替代鱼粉对大菱鲆鱼体水分、粗蛋白、粗脂肪及灰分含量均无显著影响(P0.05)。各处理组干物质和粗蛋白的表观消化率之间也未出现显著差异(P0.05)。研究表明,在本实验条件下SPC不能作为大菱鲆饲料中替代鱼粉的有效蛋白源,造成SPC替代效果较差的主要原因是其对大菱鲆饲料适口性的显著影响。     

Evaluation of solid‐state fermented protein concentrates as a fish meal replacer in the diets of juvenile rainbow trout,Oncorhynchus mykiss

We evaluated four fermented protein concentrates (FPCs) as a fish meal replacer in juvenile rainbow trout, Oncorhynchus mykiss. Ten diets were formulated to contain low‐temperature fish meal (LT‐FM), Vietnam fish meal (VT‐FM) and four types of FPCs as fish meal replacers (FPC‐A, B, C & D) at 30% and 50% FM replacement levels. FPC‐A was a mixture of solid‐state fermented soybean meal (SBM) and corn gluten meal (CGM) with Bacillus subtilis; FPC‐B was pretreated acid‐hydrolysed FPC‐A; FPC‐C and FPC‐D were FPC‐A + 2% shrimp soluble extract (SSE) and FPC‐B + 2% SSE, respectively. Triplicate groups of fish (average 15.4 g) were fed one of the experimental diets for 8 weeks. At the end of the feeding trial, fish fed the LT‐FM, FPC‐B, FPC‐C and FPC‐D diets showed significantly higher growth performance at 30% FM replacement than those of fish fed the FPC diets at 50% FM replacement. Fish fed 30FPC‐B, 30FPC‐C and 30FPC‐D diets showed higher weight gain (WG) than fish fed 30FPC‐A diet. Haematological parameters showed no clear trends among the experimental groups. Superoxide dismutase, lysozyme and myeloperoxidase activities were found to be higher in fish fed the LT‐FM, FPC‐A, FPC‐B, FPC‐C and FPC‐D diets at 30% FM replacement than in fish fed the FPC diets at 50% FM replacement. Antinutritional factors such as α‐ and β‐conglycinin, glycinin, trypsin inhibitors or zein were absent in FPC compared with SBM and CGM. Intestinal villi length and muscular thickness were significantly reduced in fish fed the VT‐FM and FPC diets at 50% FM replacement compared to fish fed the LT‐FM and FPC diets at 30% FM replacement. The results show that FPC‐B, FPC‐C, FPC‐D could replace up to 30% of LT‐FM in juvenile rainbow trout.     

Development of plant‐based diets and the evaluation of dietary attractants for juvenile Florida pompano,Trachinotus carolinus L.

Sustainable and profitable commercial aquaculture production of marine fish species is dependent on the development of sustainable protein sources as substitutes for expensive animal meals such as fishmeal (FM). Previous Florida pompano Trachinotus carolinus studies have indicated that poultry by‐product meal (PBM) and meat and bone meal can be used to produce a FM‐free diet if suitable levels of nutrients (such as taurine) are included in the diets. In this study, we attempted to develop an all‐plant protein diet by removing the animal proteins in practical diets for pompano by substituting back select ingredients. A series of eight FM‐free diets were formulated, four systematically replaced soybean meal (SBM) with soy protein concentrate (SPC) and four replaced PBM with SPC. Based on the results, there is no clear disadvantage to the use of SPC as a replacement for SBM. However, the complete removal of PBM resulted in reduced performance. Two additional growth trials were conducted to supplement additional amino acids including glycine, valine and histidine, a proprietary chemical attractant mix, fish protein concentrate and squid hydrolysate to improve the growth of pompano when fed all‐plant protein diets. The only improvement in performance occurred with the squid hydrolysate. These results demonstrate that using soybean meal, soy protein concentrate and corn gluten meal as the primary protein sources, a plant‐based feed formulation can be developed, but the removal of all animal proteins is not yet feasible.     

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.     

Evaluation of barley protein concentrate and fish protein concentrate,made from trimmings,as sustainable ingredients in Atlantic salmon (Salmo salar L.) feeds

Barley protein concentrate (BPC) was tested as a protein source in the diets of Atlantic salmon post‐smolts. Fish were fed one of four experimental diets consisting of a fish meal/soya protein concentrate control (CT) along with two feeds supplemented with increasing levels of BPC replacing the more costly SPC. A fourth diet partially replaced FM in the high BPC diet with a liquid fish protein concentrate (FPC) made from fish trimmings. No significant differences were observed in terms of growth at the end of the 12‐week feeding period, although the protein efficiency ratio (g gain g^?1 protein consumed) was significantly lower for the control compared to fish fed diets containing either BPC only or FPC and BPC. This suggests that diets containing BPC had a beneficial effect when compared to the control diet. Furthermore, the lack of any detriment to fish growth in diets containing BPC suggests there are no significant issues regarding any negative effects of potential antinutritional factors which can otherwise be the case with other plant origin products. The data presented in this study indicate that BPC and FPC are products which could be of benefit to salmon culture, and related species, in providing a valuable new raw material to the industry.     

Voluntary feed intake,nitrogen and phosphorus losses in rainbow trout (Oncorhynchus mykiss) fed increasing dietary levels of soy protein concentrate

High energy extruded diets were formulated to contain the same level of protein supplied either by soy protein concentrate (SPC) or fish meal. Three experiments were performed in order to measure voluntary feed intake and feed waste, faecal losses and soluble losses of nitrogen and phosphorus in rainbow trout (average body weight: 100 g). Voluntary feed intake and growth performance of fish fed with demand feeders were not different when diets contained 0, 50 or 75 % SPC instead of fish meal. Total replacement of fish meal by SPC led to a significant decrease in feed intake and resulted in poor growth. This was partly due to methionine deficiency in the SPC based diet. With the addition of crystalline DL-methionine in the diets, an improvement of feed intake and growth performance was apparent. Protein digestibility was high, regardless of the protein source. Excretion of ammonia and urea increased with the level of SPC in the diet. Nitrogen losses decreased when methionine was added to the diet containing only SPC as a protein source. Availability of phosphorus increased with the level of SPC in the diets. Daily soluble losses were not affected by the dietary treatments but the pattern of phosphorus excretion after feed intake was modified. The rise in soluble phosphorus in water occurred later when fish were fed diets with soy protein whatever the dietary level of soy protein concentrate.     

Performance and immunological responses of rainbow trout (Oncorhynchus mykiss) fed bioprocessed plant‐based proteins

Marine‐derived fish meal (FM) is a traditional component of commercial aquaculture feeds for many farmed fish species. Modern bioprocessing technologies have been developed to produce high‐protein plant‐based ingredients for aquafeeds to further reduce FM and other conventional animal protein sources. A 90‐day feeding trial using juvenile rainbow trout (Oncorhynchus mykiss) (27.9 ± 1.4 g; mean ± SE) was completed to evaluate growth, feed efficiency, general health and immunological responses to diets containing experimental plant‐based protein sources and reduced FM. Trout were fed one of four dietary treatments: experimental bioprocessed soy protein concentrate (BSPC), commercially available enzymatically hydrolysed soy protein concentrate (CSPC), experimental bioprocessed barley protein concentrate (BBPC) and a FM control (FMC). At trial termination, there were no significant differences in relative growth (RG) or specific growth rate (SGR) between fish fed either FMC or BSPC (p > .05). Fish fed either CSPC or BBPC resulted in significantly lower RG and SGR than the FMC (p < .05). Significant respiratory burst analysis differences were observed among treatments at day 90 (p < .01), for fish fed either FMC or CSPC diets. This assessment of bioprocessed plant‐based protein ingredients facilitates the characterization and incorporation of bioprocessed soy and barley protein as the industry continues to evaluate FM replacements in rainbow trout feeds.