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Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin-based diets (400 g kg−1 CP; 18.69 kJ g−1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg−1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg−1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg−1 diet. Broken-line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg−1 diet (0.096–0.179 μg thiamin kJ−1 gross energy). In experiment II, six casein–gelatin-based diets (400 g kg−1 CP; 18.69 kJ g−1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg−1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg−1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg−1 dietary pyridoxine. Broken-line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg−1 diet. Data generated during this study would be useful in formulating thiamin- and pyridoxine-balanced feeds for the intensive culture of this fish.

In this study, five diets were formulated, namely positive control, negative control (lysine deficient) without or with the addition of crystalline l-Lys·HCl, l-Lys·H2SO4 and microcapsulated l-lysine·HCl (M-Lys), and then fed to channel catfish with an initial body weight of 76.0 ± 0.3 g to investigate the effects of various lysine sources on the growth. After 8-week feeding, the fish fed M-Lys diet, but not Lys·HCl or Lys·H2SO4 diet, had a higher weight gain, a higher protein retention ratio and a lower feed conversion ratio than that fed negative control (P

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

An 8-week feeding trial was conducted to determine the effectiveness of replacing fish meal (FM) with blends of alternative proteins in diets for white seabass (WSB, Atractoscion nobilis) at a starting weight of 5.6 g. Five diets were formulated with 400–440g kg−1 crude protein (380g kg−1 digestible). These included a high 520g kg−1 FM control diet, a series of three diets with a sequential replacement of FM containing 410g kg−1, 510g kg−1 and 630g kg−1 of a soy-based protein blend (SPC) and 200g kg−1, 100g kg−1 and 0g kg−1 FM, respectively and a fifth diet containing 550g kg−1 of a corn-based protein blend (CGM) and 100g kg−1 FM. Survival was highest in the FM control group at 99% but all other performance measures (weight gain, feed conversion ratio, specific growth rate and protein retention efficiency) were worse than the other treatment groups. Weight gain reached a maximum of 595% in the SPC 200g kg−1 FM treatment group. Performance decreased as inclusion of the soy-based protein blend increased. The CGM treatment performed comparably to the SPC 100g kg−1 FM treatment among all measures, except for survival, which was higher in the CGM 100g kg−1 FM treatment. With nutrient levels and alternative protein blends used in this study, FM can be reduced to 100g kg−1 of the diet for WSB without reductions in performance.

Four one-week growth trials were conducted on green sturgeon fry to determine the effect of feeding rate on their growth performance at 18 °C when they were fed a salmonid soft moist feeds containing 445–457 g kg−1 of crude protein and 201–207 g kg−1 of lipid. The fry used in Trials I-IV were 5–8 weeks after their initiation of exogenous feeding. Their average initial body weights were 1.63 ± 0.01, 2.63 ± 0.03, 5.08 ± 0.08 and 7.49 ± 0.05 g, respectively. Six feeding rates used were as follows: 2.5–15.0% body weight per day (% BW day−1) with a 2.5% increment in Trial I; 1.25–7.50% BW day−1 with a 1.25% increment in Trial II; and 2.0–7.0% BW day−1 with a 1.0% increment in Trials III and IV. Four replicates with 50 fry per tank in Trials I-III and 30 fry per tank in Trial IV were assigned randomly to each feeding rates. The final body weight, specific growth rate, feed efficiency, protein retention, and whole-body moisture, lipid, and energy contents were significantly (P

This study compares growth, intake and retention efficiencies of nutrients and energy between common sole (Solea solea L.) fed ragworm (Nereis virens, Sars), blue mussel (Mytilus edulis L.) and an artificial (commercial) feed. Food types were fed to common sole (mean initial body weight: 44.9 ± 2.3 g) in excess three times a day over a 54-day-period. The growth rate in common sole fed the natural prey (8.5 g kg-0.8 d-1) was significantly higher compared to the growth rate in fish fed the artificial feed (5.1 g kg-0.8 d-1). Nutrient and energy intake was significantly lower in common sole fed the artificial feed than in fish fed natural prey. The only exception was fat intake which was higher in common sole fed the artificial feed in contrast to fish fed the natural prey. Nutrient and energy retention efficiencies were significantly lower in common sole fed the artificial feed than in fish fed the natural prey. In conclusion, the low growth in common sole fed the artificial feed was related to lower nutrient and energy intake as well as lower nutrient and energy retention efficiencies. It is suggested that reduced intake of the artificial feed might be related to the high dietary fat content of the artificial feed.

A 12-week feeding trial was conducted to determine the dietary threonine requirement of fingerling Indian major carp, Catla catla (3.35 ± 0.11 cm; 0.59 ± 0.06 g). Six casein-gelatin based (33% crude protein; 3.23 kcal g−1 digestible energy) amino acid test diets with graded levels of analysed threonine (0.74%, 0.96%, 1.21%, 1.48%, 1.72% and 1.93% dry diet) were fed to satiation to triplicate groups of fish. Absolute weight gain (g per fish), feed conversion ratio, protein retention efficiency, threonine deposition, RNA/DNA ratio and carcass protein significantly improved with the increase in dietary threonine and peaked at 1.48% of the dry diet. Haematological indices were also found to be best in fish fed at 1.48% threonine diet. Quadratic regression analysis of absolute weight gain, feed conversion ratio, protein retention efficiency, threonine deposition, RNA/DNA ratio, carcass protein, haemoglobin (g dL−1), haematocrit (%) and RBCs (106 × mm−3) at 95% of maximum and minimum response exhibited the threonine requirement of fingerling C. catla between 1.35% and 1.48% dry diet, corresponding to 4.09–4.48% dietary protein. Present finding would be useful in formulating threonine-balanced feeds for the intensive culture of C. catla.

A 12-week feeding trial was conducted to determine the optimum dietary protein requirement of brook trout, Salvelinus fontinalis, at 15 and 19 degrees C. Twelve iso-energetic (22MJkg(-1)) and iso-lipidic (23%) diets (36-58% protein at 2% increments) were prepared. Fish (29.45 +/- 3.25gfish(-1)) were fed 2% of body weight per day, divided into two equal rations. The specific growth rate (SGR, %day(-1)), feed efficiency ratio (FER), productive protein value (PPV), productive lipid value (PLV) and productive energy value (PEV), apparent digestibility of diet (AD(DM)) and protein (AD(CP)) were significantly higher at optimum temperature (15 degrees C). Increasing PPV with increasing dietary carbohydrate and with decreasing dietary protein content was due to the protein-sparing effect of carbohydrates. A piecewise regression (broken line) model between the SGR and digestible dietary protein level revealed that the digestible dietary protein requirement of brook trout was 44 and 40% at 15 and 19 degrees C, respectively. When PPV (digestible protein retention basis) was modelled with a broken line, the digestible protein requirement of brook trout was 39 and 35% at 15 and 19 degrees C, respectively. A reduction in dietary protein content balanced by increased gelatinised carbohydrate might be useful for improving the protein utilization efficiency for growth at 15 and 19 degrees C; however, the growth and feed efficiency was lower at the elevated temperature.

Amino acids are vital for all living organisms including fish and histidine is an essential amino acid for fish. In view of this, dietary histidine requirement of fry Heteropneustes fossilis was determined by feeding casein–gelatin-based isonitrogenous (430 g kg−1 CP) and isocaloric (17.9 MJ kg−1 GE; 15.5 MJ kg−1 DE) amino acid test diets (10 to 20 g histidine kg−1 dry diet) to quadruplicate groups of randomly assigned fish to apparent satiety for 12 weeks. Maximum absolute weight gain (AWG; 44 g fish−1), protein retention efficiency (PRE; 20%), protein efficiency ratio (PER; 1.04), haemoglobin (Hb; 11.24 g dL−1), haematocrit (Hct; 35.11%), red blood count (RBCs; 2.98 × 109 mL−1) and lowest erythrocyte sedimentation rate (ESR; 1.92 mm h−1) were obtained at 16 g histidine kg−1 dry diet. The 95% maximum quadratic response of above data exhibited the requirement to be at 15.2, 15.1, 15.6 and 15.5 g histidine kg−1 diet. As histidine is found in higher concentration in haemoglobin, requirement obtained for Hct% and Hb is 4% greater than that required for maximizing weight gain and protein retention. Based on these results, dietary histidine requirement of H. fossilis fry is recommended between 15.1 and 15.6 g kg−1, corresponding to 35.1–36.3 g kg−1 protein.

To quantify dietary L-tryptophan requirement of fingerling Heteropneustes fossilis (6.66 ± 0.08 g), casein–gelatin-based isonitrogenous (38% CP) and isoenergetic (14.72 kJ g−1 DE) purified diets with eight levels of L-tryptophan (0.12%, 0.16%, 0.20%, 0.24%, 0.28%, 0.32%, 0.36%, 0.40% dry diet) were fed to triplicate groups of fish twice daily to apparent satiation for 12 weeks. Incremental levels of dietary tryptophan from 0.12 to 0.28% significantly (P

Eight strains of rainbow trout were introgressed to develop a single strain (H-ARS) that was selected for faster growth when fed a fishmeal-free, plant-based diet (Selection Diet). For four generations, families from these crosses were fed the Selection Diet and selected for increased weight gain. Growth and nutrient retention were compared among H-ARS and two parental strains, the House Creek (HSC) and Fish Lake (FL) fed either a fish meal or Selection diet for 12 weeks. There was a significant effect of strain (P

This study was undertaken to determine the dietary protein requirement of shi drum (Umbrina cirrosa L.) with an initial weight of 86.3±0.4 g. The fish were fed five isoenergetic diets containing dietary protein levels ranging from 35% to 59% by 6% increments [the estimated digestible protein (DP) levels ranged between 29.6% and 52.8%], and the growth response over a 10-week period was monitored. Each experimental diet was given to triplicate groups of fish. The final weight, weight gain and daily growth coefficient increased with the dietary protein level, reaching a plateau at the dietary level of 47% protein. The feed conversion ratio improved with increasing dietary protein level. The daily feed intake was significantly lower in fish fed 53% and 59% protein diets compared with those fed 35% protein diet. However, protein intake showed an increasing trend with increasing dietary protein and became significantly different between the 59% and the 35% protein diets. The protein efficiency ratio, protein retention and condition factor were not affected significantly by the dietary treatments. The final body composition was not influenced by the treatments. The recommended dietary protein percentage and DP/digestible energy (DE) ratio for juvenile shi drum diets are 51.4% (45.6% DP) and 28.5 g DP MJ DE−1 respectively.

Growth, nitrogenous excretion and energy budget of juvenile yellow catfish, Pelteobagrus fulvidraco (initial body weight 1.17 ± 0.28 g) at various levels (50%, 60%, 70%, 80%, 90% and 100% satiation per day) were investigated with feeding diet containing 40% protein. Specific growth rate of yellow catfish increased (2.79–3.34% day) significantly (P

The potential effect of body mass (m), maturity stage (ms), food type (ft), food protein (p) and lipid (li) content, and food protein-to-energy ratio, P/E (pe) on Specific Growth Rate (SGR, % day−1), Absolute Feeding Rate (AFR, g day−1), Feed Efficiency (FE, %), Assimilation Efficiency (AE, %), and Protein Retention Efficiency (PRE, %) in the common octopus was investigated. Six food types were provided ad libitum: shrimp, squid, hake, mussel, sardine and artificial one (gels made of hydrated squid flour agglutinated with sodium alginate). Estimated SGRs, AFRs, FEs, AEs and PREs were modelled with General Linear Models based on an information theory approach, using m, ms, ft, p, li and pe as potential predictor variables. SGR decreased when m increased; octopuses fed on shrimps showed the highest SGRs and the ones fed on mussels showed the lowest SGRs. AFR increased with m. Maximum and minimum FEs were observed, when food provided was shrimps and mussels, respectively. Maximum PRE was performed by octopuses fed on shrimps or sardines and minimum PRE by octopuses fed on mussels. Octopuses fed on artificial diet reached satisfactory levels of SGR (0.50% day−1) and FE (12.3%).

A 21-day growth trial was undertaken to investigate the effect of water temperature (25, 28, 31, 34, 37 degrees C) on growth, feed utilization and energy budget of juvenile Nile tilapia (Oreochromis niloticus) (initial body weight around 12 g) with four replicates at each temperature. Feed intake energy (IE), recovered energy (RE), faecal energy (FE), excretory energy (UE + ZE) and heat energy (HE) were calculated to obtain the energy budget. The results showed that feeding rate and ammonia excretion were not significantly affected by water temperature. Specific growth rate in wet weight (SGRw) and FE was significantly lower in the fish reared at 37 degrees C while no significant difference was observed between the fish reared at 25-34 degrees C. Protein retention efficiency was highest at 28 degrees C and lowest at 37 degrees C. The proportion of IE channelled into RE and UE + ZE was lower while those lost in HE was higher in the fish reared at 37 degrees C. The optimal growth temperature was estimated as 30.1 degrees C based on the regression of SGR and water temperature. Energy budget at maximum growth (34 degrees C) was: 100 IE = 27.0 RE + 1.1 (ZE + UE) + 10.6 FE + 59.2 HE. HE accounted for 69.3% and RE for 30.7% of metabolizable energy.

Dietary arginine requirement of Heteropneustes fossilis fry (3.0 ± 0.5 cm; 5.1 ± 0.3 g) was determined by feeding casein-gelatin-based isonitrogenous (400 g kg−1 crude protein) and isocaloric (17.97 kJ g−1) amino acid test diets containing graded levels of l-arginine (15, 17, 19, 21, 23 and 25 g kg−1 dry diet) for 12 weeks. Maximum absolute weight gain (AWG) (44.4), best feed conversion ratio (FCR) (1.22), highest protein retention efficiency (PRE%) (41%), energy retention efficiency (ERE%) (75%), best condition factor, hepatosomatic index and viscerosomatic index were noted at 21 g kg−1 arginine of the dry diet. Maximum body protein (189.8 g kg−1) was also obtained in fish fed above diet. Highest haematocrit value (35%), Hb concentration (9.54 g dL−1), RBC count (3.44 × 109 mL−1) and lowest Erythrocyte sedimentation rate (ESR) (1.93 mm h−1) were obtained at the above level of arginine in the diet. AWG, FCR, PRE% and ERE% data were analysed using broken-line and an exponential fit to obtain more precise dietary arginine requirement. On the basis of broken-line and exponential analyses of AWG, FCR, PRE and ERE data, inclusion of dietary arginine in the range of 20.4–22.6 g kg−1 dry diet, corresponding to 51–56.5 g kg−1 dietary protein, is recommended for formulating arginine-balanced feeds for rearing H. fossilis fry.

A 9-week feeding trial was conducted to investigate the effects of dietary Enteromorpha prolifera on the growth performance and body composition of juvenile large yellow croaker (Pseudosciaena crocea) (Richardson, 1846) (11.41 ± 1.59 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Four isonitrogenous and isoenergetic diets were formulated to contain graded levels (0%, 5%, 10% and 15%) of E. prolifera. Survival ranged from 98.7% to 99.7%, and was independent of dietary treatment (P>0.05). There were no significant differences in the feeding rate among dietary treatments (P>0.05). The specific growth rate (SGR) increased with increasing levels of E. prolifera. When the supplementation of E. prolifera was >5%, SGR was significantly higher compared with the control group (0%). The feed efficiency ratio (FER) in fish fed the diet with 5%E. prolifera (diet 2) was higher than that of the other groups, while in fish fed the diet with 10%E. prolifera (diet 3), it was the lowest (P

We have investigated the feed intake and growth in autumn-transferred Atlantic salmon (S0) during their first spring in the sea, a period of low performance in commercial production. We have compared the results with those obtained from spring-transferred smolt (S1), in order to determine whether this reduction in performance is accompanied by changes in nutrient retention, levels of muscle fat, energy status or condition factor (CF). The practical importance of the results obtained in the small-scale experiments was evaluated by studies performed at two commercial farms, both using S0 salmon. The feeding rate, rate of growth and degree of feed utilization were low during the first spring in sea, for both S0 and S1 smolt. In both commercial farms, the apparent feed intake in S0 was reduced by approximately 50% in the spring. This low-performing period coincided with reduced fat and energy retention, low levels of muscle fat and poor CF. Fat retention was reduced from 44.8% (March–May) to 15.4% (May–June) in S0, whereas protein retention did not change, indicating that the energy demand was high during the first spring in sea.

Polka-dot grouper, Cromileptes altivelis, a highly-prized fish in Asian live fish markets, is a slow-growing species. Long-chain (LCF) or medium-chain fatty acids (MCF) were fed to polka-dot grouper (14 g initial weight) for 8 weeks to see if growth could be stimulated. Five dietary treatments were compared: a control diet with low fat (56 g kg−1) or diets that contained either moderate (150 g kg−1) or high (300 g kg−1) supplements of fat that were added either as olive oil for the LCF or coconut oil for the MCF. Control fish performed well; they grew at 2.2 g week−1, had a dry matter feed conversion ratio of 1.0 and deposited dietary protein and energy at efficiencies of 25 and 26%. Fish fed LCF at moderate levels performed better than controls but, when fed LCF at high levels or MCF at any level, their performance was inferior to controls. We conclude that dietary supplementation with 150 g kg−1 of LCF stimulates growth and improves protein retention of polka-dot grouper whereas higher levels, or the same or higher levels of MCF, depress performance.

Ten isonitrogenous casein–gelatin-based diets were formulated to contain five estimated metabolizable energy concentrations (10.92, 12.29, 13.63, 14.82 and 16.16 kJ g )1 )a t two carbohydrate-to-lipid ratios (CHO : L, 5.3 and 12.8, g : g) in a 5 · 2 factorial arrangement. Each diet was assigned to triplicate groups of 11 piracanjuba fingerlings (5.25 ± 0.14 g) and fed to apparent satiation twice a day for 90 days. Higher daily weight gain was obtained by fish fed the 13.63 kJ g )1 diets for both CHO : L ratios. There was a significant reduction of feed consumption when dietary energy concentration increased above 13.63 kJ g )1 . Feed conversion ratio and apparent net energy retention improved as dietary energy increased. Apparent net protein retention tended to be lower in the highest and lowest dietary energy concentrations. The results suggest that dietary lipid energy was more efficiently utilized by piracanjuba fingerlings than carbohydrate energy. Body composition and hepatosomatic index (HSI) were not influenced by dietary CHO : L ratio. However, an increase in dietary energy concentration beyond 13.63 kJ g )1 resulted in a significant increment in lipid deposition, while body moisture and HSI decreased. Our findings indicate that at 300 g kg )1 dietary crude protein, a CHO : L ratio of 5.3 is recommended for piracanjuba, and the required energy is either 13.63 kJ g )1 if raised for aquaculture or 14.82 kJ g )1 if destined to stock enhancement.

An 83-day feeding trial was carried out to determine the eiect of diierent dietary protein and lipid levels on the growth performances and carcass composition of white seabream. Juveniles (10.7 � 0.2 g) were fed to satiation on four diets, varying in protein (15% and 28%) and lipid (12% and 16%) levels. The best growth performance was observed in ¢sh fed on diets with higher protein level. Dietary lipids did not aiect growth performance. Voluntary feed intake decreased with a increasing dietary protein level at both dietary lipid levels. Feed conversion ratio improved with the increase in dietary protein and lipid levels. Carcass composition remained unaltered by dietary protein levels (P40.05). Carcass protein content tended to decrease, while lipid content tended to increase in groups fed on 16% lipid, compared with the 12% lipid groups. Additionally, protein retention was higher in ¢sh fed on low-protein and low-lipid levels, compared with the high-protein and high-lipid group (29% vs.19%). Lipid retention increased significantly with dietary protein level (Po0.001). Energy retention improved with dietary protein, but was not aiected by dietary lipid levels. On the basis of our results, feeding white seabream on 15% dietary protein had a negative eiect on growth and feed utilization. Dietary lipid did not induce a protein-sparing action in Diplodus sargus juveniles.

Juvenile Atlantic cod (Gadus morhua) were fed extruded feeds formulated to contain 360–660 g kg−1 protein, 80–280 g kg−1 lipid and 80–180 g kg−1 starch at feeding frequencies of either once per day or every second day to satiation. The trial was conducted at 8 °C and lasted for 28 weeks during which fish were weighed five times at regular intervals. Sampling for proximate analysis was performed at the start, after 12 weeks and at the end of the trial. Fish grew from an average weight of 192 g to between 750 and 866 g, with growth being negatively affected by low dietary protein concentration. High dietary starch concentrations had some negative effects on growth, whereas changes in dietary fat concentration had no significant effect on growth. Liver indices (at the end of the experiment) varied between 80 and 170 g kg−1, and there was a negative correlation between the ratio of protein to fat and liver index. Feed conversion ratio (FCR) ranged between 0.74 and 0.88, and feed utilization improved with increasing concentrations of dietary protein and fat. Increasing dietary starch concentrations resulted in poorer feed utilization. To achieve good growth and protein retention, and avoid excessive liver size in juvenile cod, feeds should contain 500–600 g kg−1 crude protein, 130–200 g kg−1 lipid and

Effects of varying dietary digestible protein (DP) and digestible energy (DE) on protein retention efficiency (PRE), weight gain, protein deposition and carcass composition for silver perch (Bidyanus bidyanus, Mitchell) were studied. Using digestibility data for silver perch, we formulated three series of diets with different DE contents (13, 15 or 17 MJ DE kg−1). For each series, a ‘summit’ diet containing an excess of protein for silver perch (based on previous research) and a ‘diluent’ diet with only 10–13% DP were formulated. By blending the summit and diluent diets together in different ratios, five diets with different DP contents were produced for each DE series. A commercial diet was also included to give 16 experimental diets in total. Eight juvenile fish (mean initial weight 1.2 g) were stocked into each of 64 × 70-L acrylic aquaria and then each of the 16 diets was randomly allocated to four replicate aquaria. Tanks were supplied with partially recirculated water (75%) at 25–27°C. Fish were fed restrictively, twice per day, based initially on 3.5% body weight day−1 with 40% of the ration given at 08:30 hours and 60% given at 15:00 hours for 59 days. Quadratic functions were fitted to each energy series to describe the relationship between DP content of diets and PRE (the asymptote of these functions were used to predict maximum PRE). For low DE (13 MJ kg−1), mid-DE (15 MJ kg−1) and high DE (17 MJ kg−1), the dietary DP contents to give maximum PRE were 24.7%, 26.1% and 30.1% respectively. Carcass fat decreased with increasing DP and increasing DP:DE ratio. Varying the dietary protein and DE also influenced other indices of fish performance. ‘Optimum’ dietary protein therefore depends on several factors. For fish fed, restrictively, the protein content needed to maximize PRE is lower than the content needed to maximize weight gain or minimize carcass fat. For fish fed to satiation, the lowest protein content for maximum weight gain is lower than for fish fed restrictively.

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.

An 8-week feeding trial was conducted to estimate the optimum dietary protein to energy (P/E) ratio in juvenile olive flounder Paralichthys olivaceus. Eight experimental diets were formulated with two energy levels and four protein levels at each energy level. Two energy levels of 12.5 and 16.7 kJ g−1 diets were included at crude protein (CP) levels of 25%, 30%, 35% and 45% with 12.5 kJ g−1, and CP levels of 35%, 45%, 50% and 60% with 16.7 kJ g−1. After 1 week of the conditioning period, fish initially averaging 8.1±0.08 g (mean±SD) were randomly distributed into the aquarium as groups of 15 fish. Each diet was fed on a dry-matter basis to fish in three randomly selected aquariums at a rate of 3–5% of total wet body weight per day for 8 weeks. After 8 weeks of the feeding trial, weight gain (WG), feed efficiency ratio and specific growth rate of fish fed 45% CP with 16.7 kJ g−1 energy diet were significantly higher than those from the other dietary treatments (P

This study was conducted to determine the optimum dietary protein level for young (an initial weight of 89 g) turbot, Scophthalmus maximus L. Duplicate groups of the fish were fed the five isoenergetic diets containing the various protein levels ranging from 290 to 570 g kg−1 diet for 45 days. Survival was not affected by dietary protein level. Weight gain and feed efficiency were improved with dietary protein level up to 490 g kg−1 diet. Dietary protein requirement of young turbot using the broken-line model was estimated to be 494 g kg−1 diet based on weight gain response. Protein efficiency ratio was not influenced by dietary protein level. The highest protein retention was obtained from the fish fed the 490 g protein kg−1 diet. Proximate composition of the fish was not significantly affected by dietary protein level. In considering these results, it was concluded that the 494 g protein kg−1 diet with 100 g lipid kg−1 diet (15 MJ kg−1 diet) provided optimal growth of young turbot under these experimental conditions.

Five diets were formulated to provide an isoproteic daily dietary intake of 15 g kg-1 day-1, while maintaining daily starch intake ranging from 0 to 40 g kg-1 day-1. The 4-week experiments started with initial mean weights of 4.7 and 4.4 g for Pangasius bocourti and P. hypophthalmus, respectively. The results clearly show the protein sparing action of starch in both species. Best protein retention was obtained with starch intake of 20 and 10 g kg day-1 for P. bocourti and P. hypophthalmus, respectively, which was equivalent to 40 and 20% starch in the feed. Pangasius bocourti and P. hypophthalmus fingerlings attained maximal growth with starch intake of 30 and 10 g kg-1 day-1, equivalent to 60 and 20% starch in the feed. It was noted that body lipid accumulation was much higher in P. bocourti than in P. hypophthalmus, and that excess dietary starch intake depressed diet digestibility and growth. (Resume d'auteur)

Isonitrogenous and isocaloric diets containing 0, 18 or 36% toasted full-fat soybean meal (FFSM) were fed to Atlantic halibut. The diets were fed to five tanks of fish each for 34 days (period 1). Four tanks from each treatment were then retained in the growth experiment for a further 32 days (period 2), while the groups of fish from one tank from each of the 0 and 36% FFSM groups were split and transferred to two metabolism tanks each. The initial weight of the fish in the growth trial was 169 ± 1 g (mean ± SEM, n=12; weight range 89–253 g) and the final weight was 317 ± 5 g. There was no significant effect of dietary treatment on specific growth rate (range, 0.8–1.1% day−1), feed consumption (0.5–0.7% body weight day−1), feed efficiency (1.3–1.6 g wet gain g dry feed−1), protein retention (48–55%) or energy retention (49–57%). The fat, protein and energy concentrations in the fish increased during the trial and were not affected by the diet. The hepatosomatic index in fish fed with 36% FFSM diet was significantly lower (1.7%) than in the other groups (2.2%) (P

This study determined the effect of dietary protein and energy levels on growth and feed utilization of the Thai native frog (Rana rugulosa Weigmann). The frogs were fed four isocaloric diets (5300 kcal kg−1) with protein levels 30, 35, 40 and 45% in experiment 1 and with four isonitrogenous (37%) diets with gross energy levels of 4500, 4900, 5300 and 5700 kcal kg−1 in experiment 2. The frogs were fed to apparent satiation twice daily for 12 weeks in three replicate concrete ponds (30 frogs per pond) with an average frog weight of 3.5 and 7.8 g for experiments 1 and 2, respectively. Average weights but not survival rates were significantly different at the end of the study. Feed intake, energy intake and protein efficiency ratio of frogs fed the 30–45% protein diets were not significantly different. Feed conversion ratios of frogs fed the 30% protein diet were significantly higher than for those fed 35, 40 and 45% protein diet. The amount of protein consumed by frogs fed the 30% protein diet was significantly lower than frogs fed the 35, 40 and 45% protein diets. Energy retention in frogs fed the 35% protein diet was significantly higher than other treatments. Protein retention in frogs fed diets with 30 and 35% protein was significantly higher than the frogs fed the 40 and 45% protein diet. The optimum protein level was determined as 36.72%. In experiment 2, frogs were fed with four levels of energy in a diet with a constant protein level of 37%. The average final weight and average daily gain of frogs fed with the 4900 kcal kg−1 diet were significantly higher than the other treatments. Frogs fed with the 4500 kcal kg−1 diet had significantly higher feed intake, feed conversion and lower protein efficiency ratio than frogs fed with the 4900–5700 kcal kg−1 diet. The amount of protein consumed by frogs fed the 4900–5700 kcal kg−1 diet was significantly less than frogs fed diet with 4000 kcal kg−1, but energy consumed by frogs fed the 5300–5700 kcal kg−1 diet was significantly greater than those fed the 4500–4900 kcal kg−1 diet. On the other hand, protein and energy retention in frogs fed the 4900 kcal kg−1 diet were not significantly higher than other treatments. Survival rate and body composition were similar in all treatments. The studies indicate optimum dietary protein, energy and protein to energy ratio were 36.7%, 4900 kcal kg−1 and 74.89 mg kcal−1, respectively.

An 11-week feeding trial was conducted to evaluate the effects of dietary protein and/or energy levels on growth, feed efficiency and proximate composition of juvenile (average weight: 21.5 g) common carp (Cyprinus carpio L.) fed various diets based on constant daily protein input. Five experimental diets were prepared. One group of diets (diets 1, 2 and 3) contained three crude protein (P) levels (35%, 40% and 45%) with a constant gross energy (GE) of 3.8 kcal g-1 diet. The second group of diets (diets 4 and 5) were formulated to contain a GE of 4.3 or 4.9 kcal g-1 diet and 40% or 45% protein levels, respectively, where GE/P was constant at 10.8 kcal g-1 protein. Fish receiving diet 1 served as the control; they were hand-fed to visual satiety. Feed allowance for diets 2 and 4 was 87.5% of the control. Feed allowance for fish receiving diets 3 and 5 was 77.8% of the control. Thus, all tanks received the same daily protein input. When gross energy in the diets was constant, 3.8 kcal g-1 diet, weight gain of fish fed diet 2 at 87.5% satiation was significantly higher than that of fish fed diet 3 at 77.8% of satiation. When the GE/P in the diets was constant, 10.8 kcal g-1 protein, weight gain of fish fed diet 1 was significantly higher than that of fish fed diet 5 at 77.8% satiation. The feed efficiency ratio (FER) for diets 2-5 was significantly higher than for diet 1 at constant GE and GE/P, and this improved linearly as dietary protein levels increased. The protein efficiency ratio (PER) for diet 2 was significantly higher than for diet 3 at constant GE. However, PER was not significantly different at constant GE/P. Protein retention of fish fed diet 2 was significantly higher than that of fish fed diet 3 at constant GE. Protein retention of fish linearly decreased at constant GE/P. The energy efficiency ratios (EER) for diets 2 and 3 were significantly higher than for diet 1 at constant GE. Moisture and protein contents of the whole body of fish were not significantly different at constant GE, but they decreased linearly at constant GE/P. The lipid content of fish fed diet 1 was significantly lower than that of fish fed diet 2 at constant GE, and body lipid content linearly increased at constant GE/P. These results indicate that growth and feed efficiency for common carp fed a 40% protein diet with 3.8 kcal g-1 diet GE at 87.5% satiation rate was superior to those for the fish fed either a 35% protein diet with 3.8 kcal g-1 diet GE at 100% satiation rate or a 45% protein diet with either a 3.8 or 4.9 kcal g-1 diet GE at 77.8% satiation rate.

The growth, food utilization and amounts of nitrogen and phosphorus lost into the water by rainbow trout (initial size 485 g) fed on low-fat Baltic herring and supplemented with a low-protein dry diet fed separately were studied in an 18-week net cage trial. Similarly to balancing protein and nonprotein energy in full diets, giving nonprotein energy in different feeds several hours apart improved the protein retention of low-fat herring to a level comparable to a commercially available dry diet control. The amounts of nitrogen and phosphorus lost into the water were also reduced to the same extent. The losses from the plain herring-feeding were twice as high. The improved protein retention and reduced nutrient losses were accompanied by 15–25% reductions in growth of the fish compared with the control dry diet. The growth of the fish fed on plain herring was 14% lower than the growth on the dry diet control.

In two experiments the effects of wide range of feeding intensities on energy and protein retention and on efficiency of utilization of energy and protein by carp (Cyprinus carpio L.) were studied. The feeding period varied between an initial live weight (LW) of 160g to a final LW of 520g. The utilization of ME for gain (kg) was high with values of 0.6–0.8 at an adequate feeding level but decreased significantly to 0.3–0.1 at the lower levels of energy supplied. Deposition of 1 g protein required 44 kJ and 1g fat required 52 kj ME.

In order to evaluate the effects of dietary protein and lipid levels on the growth, feed utilization and body composition of Heterotis niloticus fingerlings, a factorial experiment with three replicates was conducted. Six experimental diets containing three crude protein levels (28%, 32% and 36%) and two crude lipid levels (6% and 13%) were tested. Heterotis niloticus (2.34 g) were fed with the diets to apparent satiation, twice a day. For 56 days, weight gain (WG), specific growth rate (SGR), feed efficiency (FE) and protein retention (PR) were significantly affected by dietary protein and dietary lipid levels respectively (P

Summary This study evaluated the growth performance and body composition of Oreochromis niloticus fingerlings (average initial weight 16.53 ± 0.44 g) fed 9 experimental diets (A, B, C, D, E, F, G, H and I) containing three different levels of protein (26, 31 and 36 g 100 g )1 ) at three different gross energy (GE) levels (16, 19 and 22 MJ kg )1 ) for a period of 64 days. Significant differences were observed in the feed consumption, body weight gain, specific growth rate (SGR), condition factor (k), feed conversion ratio (FCR), protein efficiency ratio (PER), net protein retention (NPR) and apparent net energy retention (ANER) values of fish when the energy level of diet was increased at different protein levels. The maximum weight gain, SGR and k were observed on diet F containing 36% protein and an energy level of 19 MJ kg )1 of dry feed with a protein to energy (P ⁄ E) ratio of 18.96 (g protein MJ )1 GE). A further increase in the energy content of the diet (22 MJ kg )1 ) at the same protein level (Diet I) did not produce any improvement in the growth performance. Lowering the energy level at the same protein level significantly affected the growth performance. Fish fed diet B containing 31% protein and a lower energy level of 16 MJ kg )1 with the same P ⁄ E ratio of 18.61 as diet F showed significantly lower weight gain and growth performance than diet F. Diets E and H containing 31% crude protein at all three energy levels produced similar results as diet B. The poorest FCR was observed when the diet contained both lower levels of protein and energy. Fish fed diet G, containing 26% protein at high energy level (22 MJ kg )1 ), showed the best PER and NPR values. The PER and NPR were the poorest on diet C containing 36% protein at low energy level (16 MJ kg )1 ). The body moisture content at all protein levels decreased (P 0.05) in body protein content. Our results indicated the optimum P ⁄ E ratio for O. niloticus as 18.96 g protein per mega joule of gross energy at 36% dietary protein level and a dietary gross energy value of 19 MJ kg )1 .