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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 more...

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 more...

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. more...

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 more...

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%). more...

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. more...

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. more...

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. more...

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. more...

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 more...

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. more...

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) more...

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 more...

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. more...