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1.
A fish feeding trial was conducted in a warm‐water recirculating system for 8 weeks to assess the nutritive value of processed mucuna seeds as a dietary protein replacement for fish meal in practical diets of tilapia. Diets 2–6 contained mucuna seeds processed as follows: raw, soaked in water, soaked in sodium bicarbonate solution (0.07%), soaked in ascorbic acid solution (0.1%) or soaked in water containing 3% of freeze‐dried moringa leaf powder, followed by autoclaving. The mucuna seed meals were then used to replace 25% of the total dietary protein in each diet. The performance of fish fed these diets was compared with fish fed a fish meal‐based control diet (diet 1), which contained 35% protein. All diets were prepared to be isonitrogenous and isoenergetic. Each treatment had three replicates, using seven fish per aquarium, with a mean initial body weight of 3.9 ± 0.06 g. Fish were fed five times about their maintenance level (3.0 g feed × body weight (kg)?0.8 day?1), and no mortality was observed during the experiment. The growth rate, feed conversion ratio and protein productive value of fish fed diets 1, 3, 4, 5 and 6 were similar. However, with regard to energy retention and apparent net lipid utilization, the values observed in fish fed diet 1 were similar to those of fish fed diets 5 and 6, and diet 6, and significantly higher than other dietary groups. Fish fed diet 2 showed a significantly (P < 0.05) reduced growth performance, higher carcass moisture and ash contents, and lower levels of lipid and energy compared with all other dietary groups. Fish fed diet 2 had a significantly lower plasma cholesterol level compared with other diets. However, no significant variation of muscle cholesterol was found between the dietary groups. Even though the hepato‐somatic index of the fish fed diets 3, 4, 5 and 6 was significantly lower than diet 1, these values appeared to be significantly higher compared with fish fed diet 2. The present study indicates that the inclusion of mucuna seed meal (replacement of 25% of total dietary protein of feed) after soaking in any one of the tested solutions followed by autoclaving significantly improved the growth performance and feed utilization of tilapia compared with that of the raw seeds. Moreover, these values were similar to the performance obtained with the fish meal‐based control diet 1. This might be due to the relative reduction of anti‐nutrients, particularly the non‐protein amino acid 3, 4‐dihydroxyphenylalanine, and increased palatability and nutrient availability of processed beans.  相似文献   

2.
Indian major carp fingerling, Cirrhinus mrigala (3.85±0.75 cm, 0.52±0.21 g), were fed isonitrogenous and isocaloric diets (40% crude protein, 4.28 kcal g?1, gross energy) containing casein, gelatin and crystalline amino acids with graded levels of l ‐threonine (1.00, 1.25, 1.50, 1.75, 2.00 and 2.25 g 100 g?1, dry diet) to determine the dietary threonine requirement. The feeding trial was conducted in triplicate for 8 weeks. Diets were fed twice a day at 08:00 and 16:00 hours at 5% body weight day?1. The ration size and feeding schedule were worked out before the start of the feeding trial. Highest weight gain (304%) and best feed conversion ratio (1.43) were evident in fish fed diet containing 1.75% dietary threonine. Second‐degree polynomial regression analysis of weight gain, feed conversion ratio and protein efficiency ratio data indicated the dietary threonine requirement to be at 1.84%, 1.81% and 1.78%, respectively, corresponding to 4.60%, 4.52% and 4.45% of dietary protein. Minimum carcass moisture, fat and maximum carcass protein were evident in fish fed 1.75% threonine level. However, ash content did not affect body composition, except the 1.00% threonine level, which showed a significantly higher ash content value. Based on the above results, it is recommended that the diet for C. mrigala should contain threonine at 1.80 g 100 g?1 dry diet, corresponding to 4.50 g 100 g?1 dietary protein for optimum growth and efficient feed utilization.  相似文献   

3.
A ten‐week feeding trail was conducted to investigate the effects of increasing DL‐methionine (Met) supplementation on the success of fish meal (FM) replacement with plant proteins in practical diets for juvenile gibel carp, Carassius auratus gibelio. Twelve isoenergetic diets were formulated including two 150 g kg?1 FM diets (Diet 1—positive control 1 reflecting a commercial diet and Diet 2—positive control 2 reflecting a commercial diet but with balanced essential amino acid (EAA) profile) and ten 50 g kg?1 FM diets (negative controls) supplemented with graded levels (0–3.0 g kg?1) of DL‐Met (Diets 3–12). Each diet was fed to triplicate groups of gibel carp, near satiation four times daily for 10 weeks. Diet 2 with balanced EAA profile produced better final weight, specific growth rate (SGR) and feed conversion ratio (FCR) than the negative control diet containing no supplemental Met (Diet 3), but did not significantly differ from Diet 1. However, DL‐Met supplementation (0.5–3.0 g kg?1) in the negative control diets (Diets 4–12) produced growth performances similar to those fed the positive control diets (Diets 1 and 2). Based on quadratic regression analysis, the optimal dietary Met level with 5.2 g kg?1 of dietary cysteine (Cys) was found to be 7.1 g kg?1 dry diet for SGR and FCR. The corresponding total sulphur amino acid requirements (Met + Cys) of this species were calculated to be 12.3 g kg?1 dry diet for SGR and FCR. DL‐Met supplementation in 50 g kg?1 FM diets showed a decreasing trend in plasma cholesterol contents (p < .05). No significant differences were observed in whole‐body composition, plasma protein, triglyceride and free EAA contents among dietary treatments, while plasma aspartate transaminase, albumin and ammonia contents were significantly influenced by dietary Met levels. Juvenile gibel carp grew equally well on 150 g kg?1 FM diet or 50 g kg?1 FM diets balanced for EAA profile with supplemental amino acids. The results of this study overall indicate that balancing dietary amino acid levels with DL‐Met supplementation is a key strategy in successfully reducing FM levels in the diets of gibel carp.  相似文献   

4.
An 8 weeks feeding trial was conducted to investigate the effect of dietary cerium (Ce) and its complex with chitosan oligosaccharide (COS‐Ce) on growth performance and cadmium (Cd) accumulation of turbot, Scophthalmus maximus L. under Cd stress. The basal diet (Diet 0) was formulated without Cd and cerium as the control. Seven other experimental diets (Diets 1–7) were formulated with supplementation of 50 mg Cd2+/kg feed, 50 mg Cd2+/kg and 50 mg Ce3+/kg feed, 50 mg Cd2+/kg and 100 mg Ce3+/kg feed, 50 mg Cd2+/kg and 200 mg Ce3+/kg feed, 50 mg Cd2+/kg and 50 mg COS‐Ce/kg feed, 50 mg Cd2+/kg and 100 mg COS‐Ce/kg feed, and 50 mg Cd2+/kg +200 mg COS‐Ce/kg feed. Results of the present study showed that, compared with the control group, the condition factor in fish fed the diet with 50 mg Cd2+/kg feed (Diet 1) was significantly lower, whereas the Cd concentration in liver and kidney of fish fed the diet with 50 mg/kg Cd2+ (Diet 1) was significantly higher (P < 0.05). The high Cd accumulation of fish fed diets with sole 50 mg/kg Cd (Diet 1) could be significantly decreased by 51.72% after supplementation of 200 mg COS‐Ce/kg in the diet (Diet 7). These results suggested that elevated COS‐Ce could effectively protect against dietary Cd accumulation in turbot.  相似文献   

5.
Sexually immature Arctic charr, Salvelinus alpinus (Linnaeus), were fed one of five isoenergetic practical diets of differing lipid:protein ratios (0.98, 0.67, 0.41, 0.26, 0.19) for an 84‐day period to examine the influence of diet composition on growth, and growth hormone (GH) and thyroid hormone physiology. All five diets supported growth at approximately the same rate, but the diet with a lipid:protein ratio of 0.98 had the lowest weight gain and highest food conversion ratios. A GH enzyme‐linked immunosorbent assay (ELISA), developed for use with oncorhynchid fishes, was validated for use with Arctic charr. Plasma GH concentrations were significantly higher in fish fed the diet with a lipid:protein ratio of 0.98, and there were significant direct and inverse correlations between plasma GH levels and dietary lipid and protein content respectively. There were no significant differences in pre‐ and post‐prandial plasma GH concentrations for any group. There were significant post‐prandial elevations of plasma triiodothyronine (T3) and thyroxine (T4) for fish fed the lower lipid:protein ratio diets, but there were no differences related to the diets. The results are discussed in terms of GH as a factor in the regulation of lipid and protein homeostasis in fishes.  相似文献   

6.
A feeding trial was conducted in aquaria with juvenile hybrid tilapia (Oreochromis niloticus×Oreochromis aureus) to evaluate the use of different protein sources in combination with distillers dried grains with solubles (DDGS). Twelve 110‐L glass aquaria were stocked with 28 juvenile (2.7±0.5‐g) hybrid tilapia per aquarium. Three replicate aquaria were randomly assigned to each of the four dietary treatments. Diets were isonitrogenous and isocaloric. The control diet contained 12% fish meal and 41% soybean meal as the primary protein sources (Diet 1). Each experimental diet contained 30% DDGS by weight, in combination with 8% fish meal and 34% soybean meal (Diet 2), 26% meat and bone meal (MBM), and 16% soybean meal (Diet 3), or 46% soybean meal alone (Diet 4). Fish were fed to apparent satiation twice a day for 10 weeks. There were no significant differences (P>0.05) in average weight gain, specific growth rate (SGR), feed conversion ratio (FCR), and protein efficiency ratio (PER) among tilapia fed Diets 1, 2, and 3. Fish fed Diet 4 had significantly lower (P<0.05) average weight gain, SGR, and PER than fish fed Diets 1 and 3. Relative cost per unit weight gain for Diets 1, 2, and 3 were statistically similar (P>0.05), while cost per unit weight gain for Diet 4 was significantly higher (P<0.05) than other diets. Diet 3 represented approximately a 20% cost savings compared with the control diet, with no reduction in growth. This study indicates that diets without fish meal containing 30% DDGS in combination with MBM and soybean meal provide good growth in tilapia. A diet without animal protein did not support acceptable growth.  相似文献   

7.
This study was conducted to evaluate and refine the dietary lysine requirement of Atlantic salmon (Salmo salar) smolts using both the dose–response technique to determine the minimum dietary requirement and different ration levels to determine the maintenance lysine requirement and the efficiency of lysine utilization for growth. Diets containing 1.97–3.16% lysine (presented in protein‐bound form of lysine) were fed to satiation or at 25–75% ration levels to smolts during the last week in fresh water and the following 9 weeks in seawater. Based on the exponential lysine gain response to increasing dietary lysine concentrations, the minimum lysine requirement was found to be 2.67% of diet (dry matter basis; protein‐bound form or 3.05% free form). The smolts fed the unsupplemented diet maximally utilized the digestible lysine intake for growth. The efficiency of digestible lysine utilization for growth was 0.85 in the diet containing 2.88% lysine and the maintenance requirement was 21.7 mg digestible lysine kg?0.7 day?1.  相似文献   

8.
This study investigated the utilization level of rice wine residual (RWS) in a diet for juvenile Nile tilapia. The effects of RWS in diets were evaluated for growth (at week 4), fillet composition, haematological and blood chemical parameters (at weeks 3 and 6) and intestinal morphology (at week 6). The dietary treatments (each diet in triplicate groups) consisted of seven isonitrogenous (320 g kg?1 crude protein) servings that were formulated to include RWS at levels of 0 (control diet), 75, 150, 225, 300, 375 and 450 g kg?1 dry diet (Diets 1–7, respectively) and a commercial diet (Diet 8). The growth performances of fish in the groups on Diets 1–4 did not differ significantly. There were no marked variations in fillet composition, serum lysozyme, haematological profiles and blood urea nitrogen (BUN) among treatment diets, except for haematocrit and BUN (week 3) and haemoglobin (week 6) of fish on Diets 6–7. While the blood glucose increased as the amount of RWS incorporation increased (P < 0.05), the cholesterol decreased (P < 0.05). Only intestinal morphometry of fish fed Diet 7 differed significantly from any of the other treatments. Taken together, RWS (at 225 g kg?1 diet) has the potential for use in juvenile Nile tilapia diet without negative effects.  相似文献   

9.
This study was conducted to investigate the effect of fish protein hydrolysate on growth performance, insulin‐like growth factor I (IGF‐I) levels and the expression levels of liver IGF‐I mRNA in juvenile Japanese flounder (Paralichthys olivaceus). Fish hydrolysate was produced by enzymatic (alcalase and flavourzyme) treatment and size‐fractionated by ultrafiltration. The permeate after ultrafiltration (UF) and the non‐ultrafiltered fish hydrolysate were tested as feed ingredients using high plant protein diets. Fish meal was used in the control diet (FM). The feeding trial lasted for 60 days, and fish fed with 37 g kg?1 UF showed the best growth, feed efficiency, digestibility and protein utilization. Plasma IGF‐I level was examined with radioimmunoassay, and the expression levels of liver IGF‐I mRNA were evaluated using real‐time PCR normalized against the 18S rRNA gene. Plasma IGF‐I levels were significantly increased by inclusion of fish protein hydrolysate. Liver IGF‐I mRNA expression was significantly higher in fish fed with 37 g kg?1 UF diet than fish fed with control diet. The results indicated that small molecular weight compounds from fish protein hydrolysate showed a positive effect on growth and feed utilization in juvenile Japanese flounder. Dietary fish protein hydrolysate could improve plasma IGF‐I levels and liver IGF‐I mRNA expression in Japanese flounder.  相似文献   

10.
The aim of this study was to evaluate growth, biochemical composition and dietary nutrients utilization in Octopus vulgaris fed on four diets based on bogue Boops boops, from different origin and in two presentations: fresh discarded bogue (aquaculture by‐product) (DB‐f), fresh wild bogue (low price trash species) (WB‐f), discarded bogue agglutinated moist diet (DB‐m) and wild bogue agglutinated moist diet (WB‐m). Diets based on DB showed higher lipid content (19–26% dw) than those based on WB (5–6% dw). Octopuses fed on DB‐based diets showed higher growth (1.5–1.9% day?1) and higher protein efficiency ratio (0.64–0.69) than those fed on WB‐based diet (1.1–1.5% day?1 and 0.36–0.37 respectively), which suggests good utilization of dietary lipids and also a possible protein sparing effect by lipids in O. vulgaris. Octopuses fed on diets presented fresh showed a higher growth (1.9–1.5% day?1) and a higher feed efficiency (62–65%) than those fed on agglutinated diets (1.1–1.5% and 52–60% day?1 respectively). Regarding fatty acids, the digestive gland clearly reflected dietary lipid and fatty acid profile, while muscle showed a more stable composition. Low dietary ARA content reflected in octopus tissues, especially in specimens fed on DB‐based diets, which did not seem to affect growth during the experimental period.  相似文献   

11.
A feeding trial was conducted to investigate the effect of partial fish meal (FM) replacement by dietary soybean meal (SBM) on the growth and protein and lipid metabolism of the juvenile Japanese flounder. Four isonitrogenous and isolipidic diets (Diets 1–4) were formulated containing 47% protein and 9% lipid with different SBM inclusion (Diet 1, 11%; Diet 2, 16%; Diet 3, 24%; and Diet 4, 41%). The fish were fed to satiation twice daily for a feeding period of 56 days. The weight gain rate (WGR) and protein efficiency ratio of fish fed Diet 4 were significantly lower than those fed Diets 1, 2, and 3, and feed conversion ratio in the group fed Diet 4 was significantly higher than that in the groups fed Diets 1, 2, and 3. Hepatosomatic indices showed the similar trend as WGR, and the value (1.75%) for Diet 1 was significantly lower than that (1.96–2.2%) for other diets. There were no differences in whole body moisture, crude protein, crude lipid, and ash content among all treatments. With increasing dietary SBM level, serum triglyceride (TG), cholesterol (CHO), and low-density lipoprotein cholesterol (LDL-C) concentrations increased, whereas the serum total protein (TP) and high-density lipoprotein cholesterol (HDL-C) concentrations decreased. Compared with Diet 1, the serum TG, CHO, and LDL-C concentrations of fish fed Diet 4 significantly increased by 78, 37, and 36%, respectively, while the TP and HDL-C concentrations decreased by 14 and 33%, respectively. No significant differences in condition factor, blood urea nitrogen concentration, and alanine and aspartate aminotransferase activities were observed among the dietary treatments. These results indicated that dietary SBM inclusion above 24% could adversely affect the growth and protein and lipid metabolism of Japanese flounder.  相似文献   

12.
The objective of this work was to evaluate the effect of a dietary amino acid imbalance, originating from the use of a soy protein concentrate (SPC) as the major protein source, on the growth performance and amino acid metabolism of Senegalese sole (Solea senegalensis) postlarvae. Senegalese sole (85.6±24.6 mg wet weight) were fed one of two experimental diets: one based on fish meal (FM) and another based on SPC. Diets were isonitrogenous (around 56% crude protein) and isoenergetic. Diet acceptability was very good and the growth rate was 6.9% day?1 for sole eating the FM diet and 6.0% day?1 for sole eating the SPC diet. Mass‐specific ammonia excretion and the activities of selected amino acid metabolic enzymes (ALAT, ASAT and GDH) did not present significant differences between treatments, although this may have been due to the high variability found for these parameters in the SPC treatment. This variability may suggest different capacities of individual fish to adapt to the possible methionine dietary deficiency. The utilization of amino acids as a substrate for lipogenesis does not seem to be affected by the dietary protein source, since NAPDH‐generating enzymes (G6PD and ME) had similar activities in both treatments. Amino acid metabolism in Senegalese sole postlarvae seems to be slightly affected by the dietary protein source. Nevertheless, the changes induced by the SPC diet do not seem to impair growth, at least at the high dietary protein level used in this experiment.  相似文献   

13.
Three experiments were conducted that were designed to evaluate our ability to predict essential amino acid (EAA) needs of hybrid striped bass using the quantified lysine requirement and whole‐body amino acid concentrations. In the first experiment, six diets containing various amino acid profiles were fed to triplicate groups of fish initially weighing 7.7 g per fish. At the end of the 8‐week experiment, no significant differences were detected in growth rates or feed efficiencies (FE) between fish fed a practical diet containing 510 g kg?1 herring fish meal (FM) and fish fed a purified diet containing the amino acid profile of herring fish meal (CAA‐FM). Growth responses of fish fed purified diets containing 100 (HSB), 110 (HSB110), 120 (HSB120) or 140 g 100 g?1 (HSB140) of the amino acid profile of hybrid striped bass whole‐bodies were significantly lower than those of fish fed diet FM. In the second experiment, triplicate groups of fish (5.6 g per fish) were fed diets containing various energy : protein (E : P) ratios (34.8, 41.2, 47.5 and 53.9 kJ g?1 protein) and one of two amino acid profiles (CAA‐FM and HSB120) in a 4 × 2 factorial design. Carbohydrate concentration was varied to achieve the desired energy concentrations. At the end of the 8‐week experiment, weight gain and FE were significantly higher in fish fed diets formulated to simulate the amino acid profile of herring fish meal (CAA‐FM) compared with fish fed diets formulated to contain 120 g 100 g?1 of the amino acid profile of hybrid striped bass whole‐bodies (HSB120). Weight gain, FE and survival data indicated the optimum dietary E : P was 41.2 kJ g?1 protein. Dietary treatments in the final experiment included three amino acid profiles and four levels of lipid in a 3 × 4 incomplete factorial design. Dietary amino acid treatments included the amino acid profile of herring fish meal (CAA‐FM) or 120 g 100 g?1 of the predicted EAA requirement profile for hybrid striped bass (HSB120). The amino acid profile of the remaining dietary treatment (PRED+) was similar to that of the HSB120 treatment, but contained additional threonine, isoleucine and tryptophan. Diets CAA‐FM and HSB120 contained either 90, 130, 170 or 210 g kg?1 lipid, whereas diet PRED+ contained 130 g kg?1 lipid. Dietary treatments were fed for 10 weeks to triplicate groups of fish initially weighing 81.0 g per fish. Weight gain and FE were not significantly affected by dietary amino acid profile. Feed efficiency was significantly reduced in fish fed diets containing 210 g kg?1 lipid compared with fish fed diets containing 90–170 g kg?1 lipid. Intraperitoneal fat (IPF) ratio and hepatosomatic index (HSI) values generally increased as dietary lipid concentrations increased. Total liver lipid concentrations were significantly reduced in fish fed diets containing 210 g kg?1 lipid compared with those of fish fed 90–130 g kg?1 lipid. Results of this study indicate an appropriate dietary amino acid profile can be predicted for hybrid striped bass using the quantified lysine requirement and whole‐body amino acid concentrations. Further, the optimum E : P appears to be 40 kJ g?1 protein.  相似文献   

14.
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.  相似文献   

15.
To investigate the effects of dietary tryptophan on growth and glycometabolism in juvenile blunt snout bream, 450 fish (initial weight 23.33 ± 0.03 g) were fed six practical diets with graded levels of tryptophan (from 0.79 g/kg to 5.96 g/kg dry matter) for 8 weeks. Results showed that final weight, per cent weight gain (PWG), protein efficiency rate, feed intake and feed conversion ratio (FCR) were significantly improved by 2.80 g/kg diet. The maximum values of protein and ash were observed in 2.80 g/kg diet, while moisture was minimum. Lipid content of fish fed 3.95 g/kg diet was significantly higher than other diets. The highest plasma insulin‐like growth factor‐1 (IGF‐1) content was observed in 0.79 g/kg diet. In the liver, IGF‐1 mRNA levels were significantly downregulated by 2.80 g/kg dietary tryptophan, while glucokinase levels were by 3.95 g/kg, while glucose‐6‐phosphatase and phosphoenolpyruvate carboxykinase mRNA levels showed a converse trend compared with IGF‐1. Based on PWG and FCR, the optimal dietary tryptophan level was determined to be 1.99 g/kg (6.20 g/kg of dietary protein) and 1.96 g/kg (6.11 g/kg of dietary protein), respectively, using broken‐line regression analysis.  相似文献   

16.
A feeding trial was conducted to evaluate the results of replacing soybean meal (SBM) with other blend plant protein (BP) (rapeseed meal, cottonseed meal and peanut meal) sources on growth, fish body composition, biochemical parameters, non‐specific immune index and gene expression of growth hormone/insulin‐like growth factor‐1 in Yellow River carp Cyprinus carpio. The results showed that the 600 g/kg replacement with BP in diet did not affect the growth performance of Yellow River carp, but the 800 g/kg SBM replacement diet could depress the growth of fish (p < .05). The 800 g/kg SBM replacement diet significantly impacted the superoxide dismutase, malondialdehyde contents, lysozyme, alanine aminotransferase and aspartate aminotransferase activities (p < .05). Fish fed 800 g/kg SBM replacement diet showed lowest insulin‐like growth factor 1 and highest growth hormone level than that of other diets (p < .05). Both gene expression levels of GH and IGF‐I in hepatic showed significant difference among dietary treatments (p < .05), and the lowest GH and IGF‐I mRNA level in liver were found in fish fed 800 g/kg SBM replacement diet (p < .05). In conclusion, no more than 600 g/kg SBM could be replaced by BP in diet of Yellow River carp without adverse effects on the growth performance. However, 800 g/kg SBM replacement with BP in diet inhibited the growth performance, affected some blood parameters and immune response index, and down‐regulated GH and IGF‐1 gene expression of liver in Yellow River carp. Further, GH level in serum was negatively correlated with GH mRNA level in liver; meanwhile, serum concentrations of IGF‐I were positively correlated with hepatic IGF‐I mRNA expressions.  相似文献   

17.
This study evaluated the effects of increasing levels of methionine (Met) supplementation on the success of almost total replacement of fish meal (FM) with soybean meal (SBM) in diets for hybrid tilapia (Oreochromis niloticus × Oreochromis mossambicus). Fish were fed for 70 days a FM‐based diet (Diet1‐positive control) or SBM‐based diets supplemented with graded levels of DL‐methionine (Diet2 to Diet7). Contrast in dietary Met, concentration was created by supplementing Diet2‐negative control with 1.2 (Diet3), 2.4 (Diet4), 3.6 (Diet5), 4.8 (Diet6) or 6.0 g kg?1 (Diet7) of DL‐Met. Specific growth rate (SGR), feed conversion ratio (FCR), and protein gain and retention efficiency (PER) improved significantly with increasing levels of dietary DL‐Met supplementation. Moreover, nonlinear regression analysis of the effects of supplementing SBM‐based diet with graded levels of DL‐Met indicated that a dietary Met + Cys level of 15.7 and 12.5 g kg?1 diet (as fed) was required to reach 95% of maximum weight and protein gain, respectively. Supplementation of SBM‐based diet with graded levels of DL‐Met proved an effective strategy in reducing FM content in practical diets for hybrid tilapia. Data also indicate that adjustment of dietary formulas according to currently recommended Met or Met + Cys dietary concentrations is probably limiting maximum growth potential of hybrid tilapia.  相似文献   

18.
A growth trial was conducted to estimate the phosphorus requirement of European sea bass juveniles. Six experimental isonitrogenous and isoenergetic semi‐purified diets (casein based) were formulated to contain 0.48%, 0.65%, 0.77%, 0.86%, 1.05% and 1.25% phosphorus (diets D1, D2, D3, D4, D5 and D6 respectively). Dicalcium phosphate was used as dietary phosphorus source. Twelve groups of 25 fish of 10 g initial body weight were allocated to 55‐L tanks in a thermoregulated water recirculating system. Each experimental diet was assigned to duplicate groups of these fish. The trial lasted for 10 weeks and fish were fed two times a day, 6 days a week, to apparent visual satiation. At the end of the trial, final weight of fish fed diet D1 was significantly lower than that of the other groups, except of fish fed diet D4. Mortality of fish fed diet D1 was significantly higher than that of fish fed the other diets, except for diet D6. Feed efficiency and protein efficiency ratios were significantly lower with diet D1 than with the other diets. Nitrogen retention (% nitrogen intake) of fish fed diet D1 was significantly lower than in the other groups, except that of fish fed diet D4. Energy retention (% energy intake) was not significantly different among groups. At the end of the trial there were no differences in whole body composition among groups. Whole body phosphorus content averaged 0.72% (on a fresh weight basis) and was not significantly affected by dietary phosphorus content. Phosphorus retention averaged 6.1 g kg?1 weight gain and was not significantly different among groups. Phosphorus retention (% phosphorus intake) was significantly higher in fish fed diets D2 and D3 than in fish fed higher dietary phosphorus levels. Expressed per unit body weight per day, phosphorus retention was not significantly different among groups fed diets D2 to D6, while phosphorus losses linearly increased with dietary phosphorus intake. Results of this trial indicate that the phosphorus requirement of sea bass juveniles was satisfied with a diet containing 0.65% of phosphorus.  相似文献   

19.
A study was undertaken to determine the dietary protein level for optimal growth performance and body composition of juvenile Senegalese sole. Five experimental extruded diets were formulated to contain increasing levels of protein [430, 480, 530, 570 and 600 g kg?1 dry matter (DM)] and a constant lipid level, ranging from 100 to 130 g kg?1 DM. Triplicate groups of 35 sole (initial body weight: 11.9 ± 0.5 g) were grown over 84 days in 60‐L tanks supplied with recirculated seawater. Fish were fed by means of automatic feeders in eight meals per day. At the start and end of the trial, whole‐body samples were withdrawn for proximate composition analysis. At the end of 84 days of experimental feeding, daily weight gain and specific growth rate in fish fed diets P43 and P48 were significantly lower than those found in fish fed higher protein level diets (P53, P57 and P59). Similarly, feed efficiency was also significantly lower in fish fed diet P43 than in fish fed all other dietary treatments. Sole juveniles fed lower protein level diets (P43 and P48) showed a significantly lower protein content than fish fed the higher dietary protein level treatments (P53, P57 and P60). Changes within the tested dietary protein levels did not affect significantly protein productive value or total nitrogen (N) losses in fish. However, daily N gain was significantly higher (P < 0.05) in fish fed diets P53 and P60 than in fish fed the lowest protein level diet (P43). Data from the present study indicate that diets for juvenile Senegalese sole should include at least 53% crude protein to maintain a good overall growth performance. Based on a second‐order polynomial regression model, the daily crude protein requirement for maximum whole‐body N gain as estimated here for Senegalese sole juveniles was 6.43 g kg?1 body weight day?1 which corresponds to a value of 1.03 g N intake kg?1 body weight day?1. If the present data are expressed on a dietary crude protein concentration basis, the allowance for maximum protein accretion (N gain) would be met by a diet containing a crude protein level of 600 g kg?1.  相似文献   

20.
Silver perch (Bidyanus bidyanus, Mitchell) of 65 g average weight were reared at high density under controlled conditions on diets containing 24.8% and 40.6% protein. Diets were fed at 2% or 4% of the fish biomass day?1. Both protein concentrations and feeding level of the diet influenced growth and proximate composition of the fish at the end of the 50‐day growth trial. Energy requirement for maintenance for these fish was found to be 77 cal BW?0.8 and for each unit of energy retained 3.78 cal BW?0.8 needed to be supplied, and for each gram of protein retained per metabolic body weight 5.04 g were required. The results indicate that it is possible to obtain the same weight increment when feeding a 24.8% protein diet at a level of 4% body weight day?1 as compared with only 2% body weight day?1 of a 40.6% protein diet. This study indicates that the nutritional requirements for early grow‐out are similar to those found in a previous study with juvenile silver perch and adds information concerning the required relationships between dietary amino acids. The results provide information required for further refinement of nutrition for this species.  相似文献   

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