Fatty acid and amino acid composition of eggs, muscle and midgut glands of freshwater prawns, Macrobrachium rosenbergii (de Man), raised in fertilized ponds, unfertilized ponds or fed prepared diets

Fatty acid and amino acid profiles were determined in three tissues (eggs, muscle and midgut glands) from freshwater prawns, Macrobrachium rosenbergii (De Man), raised unfed in ponds with no organic fertilization, unfed in ponds with organic fertilization or fed a formulated, pelleted diet. Amino acid profiles of tail muscle and eggs were not treatment-dependent. Comparison of amino acid profiles of the diet with those of tissues of animals fed that diet suggest that dietary levels of arginine, histidine, methionine, and especially lysine may be suboptimal. Fatty acid profiles of the midgut gland, tail muscle, and to a lesser extent, eggs reflected the fatty acid composition of the diet in the fed treatment, the organic fertilizer material in the fertilized treatment and natural food organisms in the unfed treatment. Direct consumption of organic fertilizer particles by the prawns is supported by these data. Selective retention of essential fatty acids appears likely in all three treatments. Comparison of the fatty acid composition of prawn eggs and muscle tissue with that of the pelleted diet indicates that 18: 3(n-3), 20: 5(n-3), and especially 20: 4(n-6) are probably below optimal levels. However, under practical culture conditions, prawn growth may not be significantly reduced because of relatively low dietary requirements and contributions from natural foods in the ponds.     

Assessment of reference dietary amino acid pattern for juvenile red sea bream, <Emphasis Type="Italic">Pagrus major</Emphasis>

Four semi-purified diets, containing crystalline amino acids (CAAs), were fed to juvenile red sea bream, Pagrus major in order to ascertain the ideal dietary amino acid pattern for this species. A control diet containing 50% casein–gelatin as protein sources, but no CAAs were fed to the fish. The other diets contained 30% casein–gelatin and 20% CAAs. CAAs were added to diets to simulate with amino acid pattern of the red sea bream eggs protein (REP), red sea bream larvae whole body protein (RLP), red sea bream juvenile whole body protein (RJP), and brown fishmeal protein (BFP). The juveniles (average initial body weight, 1.58 ± 0.01 g) were maintained in triplicate tanks and fed twice daily for 30 days. The highest weight gain was observed in juveniles fed the RJP diet. No significant difference was observed in juveniles fed the RLP and BFP diet. Feed efficiency ratio, protein efficiency ratio and amino acid retention in the whole body were significantly (p < 0.05) affected by the simulated dietary amino acid patterns. The essential amino acid profile and A/E ratios of the whole body after the growth trial showed little difference among the dietary treatments. The results suggest that red sea bream juveniles are able to utilize high amounts of CAA in coated form. The amino acid pattern of RJP could be used as an appropriate of reference dietary amino acid for this species.     

Influence of different dietary amino acid patterns on growth and body composition of juvenile Japanese flounder, Paralichthys olivaceus

A feeding trial using five semi-purified diets (50% crude protein) was conducted to investigate the effects of different dietary amino acid patterns on growth and body composition of juvenile Japanese flounder. The control diet contained casein and gelatin as intact protein sources and four other diets contained 30% casein–gelatin (2:1, w/w) and 20% crystalline amino acids (CAA). CAA were added to the diets to simulate the amino acid pattern found in red sea bream egg protein (REP), Japanese flounder larvae whole body protein (FLP), Japanese flounder juvenile whole body protein (FJP), and brown fish meal protein (BFP), respectively. The test diets were fed to triplicate groups of juveniles (2.75±0.05 g) twice a day for 40 days to evaluate weight gain, survival, feed conversion efficiency (FCE), protein efficiency ratio (PER), and apparent protein utilization (APU). The apparent retention of total dietary amino acids in the whole body and A/E ratios of the whole body were also evaluated. The highest weight gain was observed in fish fed the diet containing the dietary amino acid pattern of BFP followed by fish fed the control, FJP, FLP and the REP diets. Percent survival, FCE, PER and APU were also significantly (P<0.05) affected by the amino acid pattern in the diets, indicating the highest value in fish fed the BFP diet. Except for a few amino acids, the amino acid composition of the whole body did not show marked differences with different dietary amino acid pattern. Results suggest that BFP could be more suitable as a reference amino acid pattern in the diet of juvenile Japanese flounder compared to the amino acid pattern of FLP, FJP or REP.     

Effects of dietary lipid sources on growth and fatty acid composition of juvenile shrimp, Litopenaeus vannamei

This experiment was conducted to evaluate the effects of dietary lipid sources on the growth performance and fatty acid (FA) composition of juvenile shrimp, Litopenaeus vannamei. Six isoenergetic and isonitrogenous semi‐purified diets containing casein, solvent‐extracted soybean meal and gelatin as protein sources, were supplemented with 60 g kg⁻¹ of lipid sources. The lipid sources included: pollack fish oil (PO), pork lard (PL), soy oil (SO), peanut oil (PN), rapeseed oil (RO) and a mixture of pollack fish oil and soy oil (POSO 1 : 1 w/w). Each diet was fed to juvenile shrimp (0.10 g average weight) four times daily in triplicate tanks to apparent satiation (feeding ratio was about 8%) for 8 weeks. At the end of the experiment, weight gain, specific growth rate and protein efficiency ratio were significantly higher for shrimp fed the diet containing PO and the POSO mixture oil than the other lipid sources. The nutritional values of SO, RO, PN and PL were similar. Shrimp fed on PO, mixture oil of POSO and SO had better survival rates than the other lipid sources, and shrimp fed the PL had the lowest survival rate. There were significant differences in lipid contents of whole body and hepatopancreas amongst the dietary treatments; however, lipid contents of tail muscle were not significantly affected by the dietary lipid sources. Shrimps fed POSO diet had higher protein content in whole body than those fed the other lipid sources, and shrimp fed PO diet had highest crude protein content of the tail muscle. A high correlation was found between dietary FA composition and FA composition of whole shrimp. FA composition of the whole body was generally affected by dietary lipid sources, especially dietary unsaturated FA.     

Feeding high inclusion of whole grain white lupin (Lupinus albus) to rainbow trout (Oncorhynchus mykiss): effects on growth,nutrient digestibility,liver and intestine histology and muscle fatty acid composition

The effect of dietary inclusion of whole grain white lupin (Lupinus albus) on growth performance, histology, muscle fatty acid composition and nutrient digestibility was investigated in an 11‐week growth and a 4‐week digestibility trial with rainbow trout (initial body weight of 54.0 ± 6.2 and 181.9 ± 3.4 g respectively). Four experimental extruded diets were formulated to contain 0%, 30%, 40% and 50% of whole grain lupin and fed to triplicate groups of fish twice a day until apparent satiation. Faeces were collected daily from each digestibility tank by decantation. No significant trends were observed with respect to growth, feed utilization, apparent digestibility coefficients or whole‐body composition (P>0.05). Conversely, increasing levels of dietary lupin led to significant decreases in the Hepatosomatic index (R²=0.75, P<0.05) and slight lipid infiltration into hepatocytes and enterocytes. Muscle fatty acid compositions were slightly affected by the dietary treatment. Polynomial regression of dietary inclusion of lupin and muscle fatty acid concentrations showed an increase in C18:1n‐9, C18:2n‐6 and C18:3n‐3 and a decrease in C20:5n‐3 with increasing dietary lupin level. These results demonstrated that whole grain lupin can be included up to 50% in commercial rainbow trout diets without negative effects.     

The effects of dietary lipid sources and lecithin on the production of giant freshwater prawn <Emphasis Type="Italic">Macrobrachium rosenbergii</Emphasis> larvae in the Mekong Delta region of Vietnam

The giant freshwater prawn, Macrobrachium rosenbergii, is cultured widely in the Mekong Delta region of Vietnam but it is often difficult or expensive for hatchery operators to purchase commercial diets used as a feeding supplement to Artemia nauplii. Therefore, in the present study, the effects of lipid sources and lecithin on the growth and survival rate of M. rosenbergii larvae were examined in order to develop suitable hand-prepared larval diets for seed production of M. rosenbergii in this area. Six egg custard diets consisting of various ratios of lipid (originating from soybean oil and squid oil) and lecithin were used for rearing Macrobrachium rosenbergii larvae. Treatments in which larvae were fed diets containing squid oil exhibited the highest body length and survival rates (7.14–7.43 mm and 51.1–68.1%, respectively), and differed significantly from other treatments (P<0.05). Use of dietary soybean oil yielded the lowest body length and survival rates (6.29–6.75 mm and 22.0–48.7%), respectively). The supplementation of dietary lecithin did not increase final body weight but did improve larval survival rates. The n-3 HUFA content of prawns fed dietary squid oil was higher than those of animals provided with other diets. These results indicated that the most appropriate diet for rearing M. rosenbergii larvae is the diet containing 3% squid oil and 1.5% lecithin.     

Effect of dietary carbohydrate-to-lipid ratios on growth, lipid deposition and metabolic hepatic enzymes in juvenile Senegalese sole (Solea senegalensis, Kaup)

A study was undertaken to determine the effect of various dietary carbohydrate‐to‐lipid ratios on growth performance, whole‐body composition and tissue lipid content in Senegalese sole (Solea senegalensis) juveniles. Data on the dietary regulation of key hepatic enzymes of the lipogenic and glycolytic pathways (glucose‐6‐phosphate dehydrogenase, G6PD; malic enzyme, ME; fatty acid synthetase, FAS; pyruvate kinase, PK and glucokinase, GK) were also generated. Four isonitrogenous (crude protein: 52% dry matter (DM)) diets were formulated to contain one of two lipid levels (11% and 21% DM). Within each dietary lipid level, the nature of the carbohydrate fraction (raw or extruded peas) was varied. Triplicate groups of 54 sole (initial body weight: 23.6±1.2 g) were grown in recirculated seawater over 67 days. Fish were fed using automated feeders. At the end of the study, whole‐body, liver, viscera and muscle samples were withdrawn for analyses. During the experimental period, the mean fish weight about doubled in all treatments. No significant differences were found in growth performance (ranging from 1.1% to 1.4% body weight day^?1) among dietary treatments. High‐fat diets increased whole‐body fat content. Similarly, daily fat gain ranged from 0.54 to 0.78 g kg^?1 day^?1 and highest values were found in fish fed high‐lipid diets. Dietary treatments also affected tissue lipid content (liver, viscera and muscle), with highest values in fish fed high‐fat diets. The nature of dietary carbohydrates had little influence on performance criteria, but affected tissue lipid deposition. The activities of G6PD, ME and FAS were depressed by elevated levels of dietary lipid, confirming the inhibitory effect of dietary fats on lipid biosynthesis. At both dietary lipid levels, ME and FAS activities were little affected by dietary carbohydrate. Activities of PK and GK were not affected by the starch level of the diets. In Senegalese sole juveniles, the lipogenic pathway is more susceptible to modulation by dietary means (particularly through lipid intake) than the glycolytic pathway.     

Effects of different dietary amino acid patterns on growth performance and body composition of juvenile giant croaker Nibea japonica

A feeding trial was conducted to investigate the effects of different dietary amino acid patterns on growth performance, feed utilization and body composition of juvenile Nibea japonica. Four semi‐purified diets were formulated to simulate the dietary amino acid profiles of juvenile giant croaker whole body protein (GCP), Peru fishmeal protein (PFP), red sea bream eggs protein (REP) and soybean meal protein (SMP) by supplementing with pre‐coated crystalline amino acids (CAA). A control diet contained only intact protein sources provided by the fishmeal and casein (2:1). Each experimental diet was fed to satiated triplicate groups of juveniles (10.73 ± 0.07 g) twice a day for 8 weeks. The highest weight gain (WG) was observed in the juveniles fed the control diet, whereas no significant differences were found between the juveniles fed the GCP and control diets. Fish fed the control, GCP, PFP and SMP diets did not exhibit any significant difference in protein efficiency ratio (PER), feed conversion (FCR) or nitrogen (N) retention. The results of this study suggest that the amino acid (AA) patterns of juvenile whole body protein could be used as a guideline in the formulation of dry diets, which also confirms that the juvenile giant croaker is able to utilize high amounts (20%) of CAA in coated form for growth.     

Evaluation of dried seaweed <Emphasis Type="Italic">Gracilaria lemaneiformis</Emphasis> as an ingredient in diets for teleost fish <Emphasis Type="Italic">Siganus canaliculatus</Emphasis>

In order to evaluate the feasibility of dried seaweed Gracilaria lemaneiformis (Bory) as a dietary ingredient for the rabbitfish Siganus canaliculatus (Park), juvenile fish (average weight 15.64 ± 0.15 g) were fed with two isonitrogenous (32% crude protein) and isolipid (8% lipid) diets for 8 weeks, with one diet incorporating 33% of dried G. lemaneiformis (DGL), which accounted for 6% protein and 17% carbohydrate (DGL-diet), and the other containing no DGL (control diet). After 8 weeks, the growth performance and feed utilization efficiency of fish fed with the DGL-diet were inferior to fish fed with the control diet, although some non-specific immunity parameters were better in fish fed with the DGL-diet compared with those of fish fed control diet. Nutritional composition (whole body composition, amino acid, and fatty acid composition in dorsal muscle) except methionine and tyrosine in muscle showed no differences between the two groups. Furthermore, the survival rate of fish and apparent digestibility coefficient of diets were the same between the two groups. These results indicated that incorporation of DGL in diet of S. canaliculatus is feasible, and further studies are recommended to optimize the level of DGL in diet of S. canaliculatus to improve growth performance.     

Effects of replacing dietary fish oil and squid liver oil with vegetable oils on the growth,tissue fatty acid profile and total carotenoids of the giant freshwater prawn, Macrobrachium rosenbergii

A feeding trial was conducted to investigate the complete substitution of either fish oil (FO) or squid liver oil (SLO) with crude palm oil (CPO), canola oil (CO) sunflower oil (SFO) or linseed oil (LO), as the sole added lipid source in diets fed to triplicate groups of giant freshwater prawn, Macrobrachium rosenbergii (initial weight = 0.42 ± 0.01 g) for 6 weeks. Prawns fed the CO or SLO diets showed significantly higher (P < 0.05) specific growth rate than those fed the FO or CPO diets. The feed conversion ratio of the prawns was significantly better when fed the CO diet, compared with the FO, CPO, SFO and LO diets. The muscle eicosapentaenoic acid content of prawns fed the vegetable oil (VO) diets were not significantly different (P > 0.05) from those fed the FO diet, although all VO‐based diets led to a significantly lower docosahexaenoic acid content compared with prawns fed the FO or SLO diet. The whole‐body total carotenoid content was significantly lower for prawns fed the SLO diet compared with prawns on the CO or CPO diets. The successful use of VO instead of marine‐based oils in prawn diets will likely reduce feeding costs associated with M. rosenbergii aquaculture.     

Egg and whole-body amino acid profile of African bonytongue (<Emphasis Type="Italic">Heterotis niloticus</Emphasis>) with an estimation of their dietary indispensable amino acids requirements

African bonytongue, Heterotis niloticus, is a river fish from the Central and West Africa basin. The species presents a great potential for fish farming and has been increasingly raised in Central and South Cameroon. The total amino acid and proximate composition of the whole body of egg, larva, juvenile, immature, and adult Heterotis were determined. Ash, moisture, whole-body protein, and lipid contents were significantly affected by size (P < 0.05). On the other hand, the amino acid composition of the whole-body tissue, when expressed as a percentage of dietary protein, was not significantly different among ontogenetic stages (ranging from 0.2 to 400 g mean body mass). The amino acid composition of the eggs was quite different to the one of whole-body tissue with lower levels of methionine, proline, and glycine, and higher levels of arginine, histidine, isoleucine, leucine, threonine, valine, serine, and alanine. The A/E ratios of adult Heterotis muscle tissue are similar to those obtained for other fish species, except for histidine and tryptophan. Based on whole-body or muscle tissue indispensable amino acids (IAA) to A/E ratios, the IAA requirement profiles for Heterotis (from larva to adult) were estimated and are similar to those of other omnivorous fish species, except for tryptophan and histidine.     

Dietary threonine requirement to optimize protein retention and fillet production of fast‐growing Nile tilapia

Threonine is the third‐limiting essential amino acid in diets based on cereal ingredients. A 4‐week trial was conducted to determine the threonine requirement of large Nile tilapia based on fish growth, feed efficiency, body composition, protein and amino acid retention. Six hundred fish (563.3 ± 15.1 g) were distributed into twenty 1.2‐m³ cages. Five diets containing 288 g kg^?1 of crude protein, 12.7 MJ kg^?1 of digestible energy and 8.9, 10.5, 12.2, 13.7 and 15.4 g kg^?1 of threonine were elaborated. Fish were hand‐fed five times a day to extruded diets. Significantly, differences in growth performance and amino acids retention among the treatments were observed. Fish fed 10.5 g kg^?1 of threonine showed higher daily weight gain, gutted weight and fillet weight (P < 0.05) compared to fish fed with other experimental diets. Diets containing 8.9–15.4 g kg^?1 of threonine did not affect whole body and muscle proximate composition. Based on second‐order regression analysis, the dietary threonine requirement estimated based on final gain, fillet weight and fillet yield was 12, 12.1 and 11.5 g kg^?1 diet, respectively. The dietary threonine requirement for maximum fillet yield of Nile tilapia was estimated to be 11.5 g kg^?1.     

Effect of dietary fish oil replacement by rapeseed oil on the growth,fatty acid composition and serum non‐specific immunity response of fingerling black carp,Mylopharyngodon piceus

An 8‐week experiment on fingerling black carp Mylopharyngodon piceus was conducted to evaluate the effects of dietary fish oil (FO) supplement on growth, fatty acid composition and non‐specific immunity responses. Five triplicate fingerling groups (initial weight = 2.72 ± 0.35 g) were fed isoenergetic and isonitrogenous diets in which the dietary FO was replaced with rapeseed oil (RO) in graded increments of 25% (0–100%). No significant effects were observed on specific growth rates, survival rates and feed conversion ratios, but there were significant differences in whole body moisture and liver lipid contents (P < 0.05), and the 100% RO replacement diet significantly enhanced hepatosomatic indexes compared to control group (P < 0.05). Other approximate whole body constituents, viscerasomatic ratios and condition factors were not influenced by dietary oil treatments. Fatty acid composition of muscle and liver was influenced by dietary fatty acid input, α‐linoleic acid and γ‐linolenic acid were significantly increased with increasing RO, but eicosapentaenoic acid, docosahexaenoic acid and the n‐3/n‐6 ratio were significantly reduced (P < 0.05). Alternative complement pathway, lysozyme and superoxide dismutase activities were not significantly influenced. These results indicate that black carp fed diets with FO supplement had similar growth and non‐specific immunity to the fish fed diet with RO.     

Tissue composition,blood biochemistry and histology of digestive organs in Senegalese sole (Solea senegalensis) juveniles fed diets containing different plant protein ingredients

The aim of this study was to determine the impact of diets with different plant protein ingredients on proximate composition, tissue metabolites and tissue fatty acid composition, as well as hepatic and intestinal histological modifications in Senegalese sole (Solea senegalensis). Fish (21.5 ± 2.8 g body weight) were fed six isonitrogenous and isoenergetic diets during 11 weeks. A control diet containing fish meal as the main protein source was compared with five experimental diets replacing 30% fish meal protein by different plant protein sources: soybean meal (SBM), soybean protein concentrate (SPC), soybean protein isolate (SPI), wheat gluten meal (WGM) or pea protein concentrate (PPC). The inclusion of different plant protein did not significantly affect growth and proximate composition of fish. The hepatosomatic index was not significantly different to the control group; however, utilization of WGM significantly increased hepatocyte size. Plasma protein values and muscle triglycerides were influenced by the inclusion of SBM and WGM in the diets respectively. Feeding fish on SBM, WGM and PPC diets significantly enhanced n‐6 fatty acid levels in muscle, particularly linoleic acid. None of the plant protein ingredient used in the diets decreased arachidonic, eicosapentaenoic as well as docosahexaenoic acid values in liver and muscle. Overall, histological studies did not reveal the existence of any intestinal alterations induced by the inclusion of different plant proteins. Despite moderate changes produced by SBM, SPC and WGM, inclusion of dietary plant protein ingredients has no major impact on growth, tissue and blood biochemistry, fatty acid profile and gut integrity of Senegalese sole juveniles.     

Inclusion of camelina meal as a protein source in diets for farmed Atlantic cod Gadus morhua

Camelina meal Camelina sativa (CM) is a potential protein source in aquaculture feeds, because of its crude protein level (39%) and essential amino acids. Two feeding experiments were conducted with Atlantic cod Gadus morhua. Cod in Experiment I (19.4 g fish^?1) were fed diets with 0%, 12% or 24% CM for 9.5 weeks at 10°C; and cod in Experiment II (14.4 g fish^?1) were fed diets with 0%, 15%, 30% or 40% CM for 13 weeks at 10°C. Growth, lipid and amino acid tissue composition were compared amongst cod fed varying levels of CM. In Experiment I, cod could tolerate the highest level of CM inclusion (24%) without affecting growth compared to cod fed the control diet. In Experiment II, growth performance was significantly affected at 30% CM inclusion compared to the control treatment, and cod fed 15% CM displayed some signs of depressed growth (reduced feed intake and weight gain). Both treatment and duration were interacting factors (P = 0.015) that determined growth performance when comparing both experiments. Muscle tissue composition was relatively unaltered with less than 30% CM inclusion; however, multivariate statistics revealed significant differences in muscle tissue fatty acid composition between cod fed 40% CM and the control diet. The tissue amino acid profile was generally unaltered because the dietary amino acid profile was consistent after CM inclusion. A few antinutritive compounds in CM may have affected palatability in diets with greater than 30% CM inclusion, which may have resulted in reduced growth performance.     

Influence of dietary protein on digestive enzyme activity, growth and tail muscle composition in redclaw crayfish, Cherax quadricarinatus (von Martens)

This study was conducted to evaluate the effects of dietary protein on digestive enzyme profiles, growth and tail muscle composition in the freshwater redclaw crayfish, Cherax quadricarinatus. Crayfish were fed five diets that consisted of a commercial crayfish pellet and experimental diets containing 13%, 18%, 25% or 32% crude protein (CP), for a period of 12 weeks. Analysis of digestive enzyme profiles from the midgut gland (MG) revealed a positive correlation between protease, amylase and cellulase activities and dietary protein level. For all treatments, carbohydrase activity levels (cellulase and amylase) were significantly higher than those detected for protease. As dietary protein was elevated, there was a general increase in specific growth rate (SGR), with the highest SGR (0.58 ± 0.06) values observed in crayfish fed the diet containing 25% CP. Feed conversion ratio (FCR) ranged between 5.84 and 6.97 and did not differ significantly among the treatment groups including the reference diet, with the exception of the low‐protein diet (13% CP) which showed an FCR of 9.31. Finally, regression analysis revealed a strong positive correlation between the level of dietary protein and CP content in the tail muscle (P=0.004; r²=0.99).     

Effects of dietary oxidized oil and vitamin E on the growth,blood parameters and body composition of juvenile Atlantic cod Gadus morhua (Linnaeus 1758)

The effects of oxidized dietary lipid and the role of vitamin E on the growth performance, blood parameters and body composition of juvenile Atlantic cod (Gadus morhua) were evaluated over a 9‐week feeding period. Four isonitrogenous experimental diets containing fresh or oxidized fish oil with or without added vitamin E (α‐tocopherol or mixed tocopherols) were fed to juvenile cod. The oxidized lipid used had a peroxide value of 94 mEq kg^?1 oil. No significant (P>0.05) differences in growth performance (weight gain and specific growth rate) or feed utilization (feed consumption and feed efficiency ratio) were observed when oxidized dietary lipid was used. The hepatosomatic index (HSI), viscerosomatic index (VSI) and haematocrit did not show any significant (P>0.05) differences among the treatments. However, erythrocyte osmotic fragility (EOF), referred to as susceptibility to haemolysis, of fish fed oxidized oil without added vitamin E was high in comparison with those fed unoxidized oil. Supplementation with α‐tocopherol appeared to decrease haemolysis, but mixed tocopherols had no significant (P>0.05) effect on EOF. The proximate composition of fish whole body was also affected by diet treatment. Fatty acid composition of liver total lipid reflected that of dietary lipid. Variations in tissue (liver and muscle) fatty acid composition among the treatments followed the same trend as those of the dietary fatty acids. Fish fed fresh oil had a higher proportion of polyunsaturated fatty acids (PUFA) in muscle and liver lipid than those fed oxidized oil. The results suggest that oxidized dietary oil affected juvenile Atlantic cod in certain tissues and that these effects could be alleviated by supplementation of sufficient amounts of vitamin E in the diet.     

Dietary arginine requirement of juvenile kuruma shrimp Marsupenaeus japonicus (Bate)

The requirements for essential amino acids by kuruma shrimp, Marsupenaeus japonicus (Bate) have not yet been determined using the dose–response method due to poor utilization of crystalline amino acids (CAA). In a previous study, we produced coated CAA that could be used to retard leaching losses. Therefore, to determine the arginine requirement of juvenile kuruma shrimp, a growth study was conducted using test diets containing six levels of coated arginine (from 1.20% to 3.19% of diet) for 42 days. Crystalline amino acids was supplemented to correspond to the amino acid pattern in the whole body protein of the kuruma shrimp except for arginine. To reduce leaching losses, CAA were coated with carboxymethylcellulose (CMC) and diets were further bound with CMC and k‐carrageenan. Test diets were fed to triplicate groups of juveniles (0.25±0.02 g) twice a day. Proximate composition and the amino acid composition of shrimp whole bodies were analysed at the end of the feeding trial. Percent body weight gain (WG), specific growth rate, feed intake, feed efficiency ratio and protein retention efficiency were significantly affected by the dietary arginine concentrations. Estimating the arginine requirement of kuruma shrimp using broken‐line analysis of percent WG resulted in a value of 2.66% of diet or 5.32% of protein. After correcting for leaching of arginine from the diets, the optimum dietary value of arginine for kuruma shrimp was a little lower than the estimated value.     

Effects of varying dietary fatty acid profile on growth performance, fatty acid, body and tissue composition of juvenile pike perch (Sander lucioperca)

Pike perch (Sander lucioperca) has been identified as specie destined to diverse European inland aquaculture, but knowledge on the nutritional requirements is weak. Therefore, we investigated the effect of varying dietary fatty acid (FA) profile by partial replacement of fish oil (FO) with vegetable oils on growth, FA and body composition of juvenile pike perch. An extruded basal diet containing 59 g kg^?1 crude lipids (FO) was added with 60 g kg^?1 FO, 60 g kg^?1 linseed oil (LO) or 60 g kg^?1 soybean oil (SO). The resulting dietary FA composition differed mainly in the triglyceride fraction and was characterized by highest amounts of linolenic acid (18:3 n‐3) in the LO diet and linoleic acid in the SO diet. Diet enriched with FO contained highest contents of highly unsaturated FA 20:5 n‐3 (eicosapentaenic acid) and 22:6 n‐3 (docosahexaenic acid). Pike perch were held in a recirculation system and each feeding group (in triplicate) was fed with experimental diets at a daily rate of 35 g kg^?1 of biomass for 57 days by automatic feeders. Weight gain and specific growth rate of experimental feeding groups ranged between 18.47 and 19.58 g and 1.37–1.45% day^?1 and was not affected by the dietary composition indicating that FO can be replaced by vegetable oils without negative impact on growth performance. In contrast to the whole body and muscle composition, liver tissue was affected by the varying diets. Liver tissues of fish fed diets enriched with vegetable oils showed significantly increased lipid contents of 162 (LO) and 147 (SO) g kg^?1 and indicate decreased lipid utilization compared with fish fed FO diet (liver lipid content 112 g kg^?1). Nevertheless, hepatosomatic index of pike perch was not influenced by dietary lipid composition. The FA profile of pike perch was generally determined by the dietary FAs.     

Dietary essential amino acids and heat increment in rainbow trout (Oncorhynchus mykiss)

Oxygen consumption attributable to apparent heat increment (AHI) was measured in relation to varying essential amino acid proportions (EAA) infused into rainbow trout,Oncorhynchus mykiss (250–450 g), induced to swim at 1 BL s^–1. Five diets, mimicking EAA concentrations in trout whole body protein, deficient in the branched chain amino acids (isoleucine, leucine and valine), containing unbalanced proportions of EAAs and supplying lysine in excessive and limiting proportions, were tested. Following infusion of the experimental diets, a significant increase in oxygen consumption was observed. Changes in plasma EAAs following infusion paralleled the time course of AHI (i.e., oxygen consumption). AHI represented the equivalent of 15–32% of the gross energy intake depending on dietary EAA composition. Diets supplying EAAs similar to trout whole body protein and limiting in lysine produced the lowest AHI values, indicating efficient utilization of dietary amino acids. Higher AHI values were associated with diets deficient in the branched chain amino acids and diets supplying lysine in excess. Duration of elevated metabolism was independent of both dietary composition and energy intake. Different proportions of EAAs in the diet can increase the energy expended as AHI. In an attempt to reduce the energy liberated as AHI, attention must be paid to the quality, quantity and balance of dietary EAAs.