Effect of dietary DP/DE ratio on apparent digestibility, growth and nitrogen and phosphorus retention in rainbow trout, Oncorhynchus Mykiss (Walbaum)

The effect of DP/DE ratio in diets for rainbow trout, Oncorhynchus mykiss (Walbaum), was investigated. To evaluate growth and body composition, groups of trout were fed three experimental diets with a constant level of gross energy (25.4 ± 0.12 MJ kg^?1 dry matter (DM)) and different digestible protein/digestible energy (DP/DE) ratios (diet A, 16. 35; diet B, 17.21; dietC, 18.23 g Mr^?1). Fat, protein and energy digestibility coefficients were not affected by the DP/DE ratio of the diets. Growth and feed utilization improved markedly as dietary DP/DE ratio increased (P < .01). The efficiency of fat, protein and energy utilization tended to increase with increasing DP/DE ratio of the diets. Nitrogen discharge in effluent water per kg of weight gain was not affected by dietary treatments (mean values for: diet A, 29.9; diet B, 29.8; diet C, 29.1 g N kg^?1 weight gain) while phosphorus discharge in effluent water fell using diets with a higher DP/DE ratio (mean values for: diet A, 7.3; diet B, 6.7; diet C, 5.9 g P kg^?1 weight gain).     

Effect of Reducing Dietary Digestible Energy to Protein Ratio on Weight Gain and Body Fat of Juvenile Channel Catfish Ictalurus punctatus1

A laboratory feeding trial was conducted to evaluate the effects of reducing digestible energy to protein (DE:P) ratios of practical diets on body fat and weight gain of channel catfish. Five diets were formulated to contain 32, 28, or 24% crude protein with typical DE:P ratios of 8.5, 9.9, or 11.4 kcal/g protein, respectively, and 28% or 24% protein with a reduced DE:P ratio of 8.5 kcal/g protein. Cellulose was used to adjust the DE:P ratio. Juvenile channel catfish Ictalurus punctatus (initial weight: 5.2 g/fish) were fed the experimental diets twice daily to apparent satiation for 12 wk. Fish fed the 28% protein diet with a reduced DE:P ratio of 8.5 kcal/g protein gained less weight and converted feed less efficiently than those fed the 28% protein diet with a typical DE:P ratio of 9.9 kcal/g protein. Fish fed the 24% protein diet with a reduced DE:P ratio of 8.5 kcal/g protein had a similar weight gain but converted feed less efficiently than those fed the 24% protein diet with a typical DE:P ratio of 11.4 kcal/g protein. Weight gain and feed conversion efficiency of fish fed the 32% protein diet with a typical DE:P ratio of 8.5 kcal/g protein were higher than for fish fed other diets except those fed the 28% protein diet with a DE:P ratio of 9.9 kcal/g protein. There were no differences in feed consumption and survival among dietary treatments. Fillet fat of fish fed the 24% and 28% protein diets with a reduced DE:P ratio was lower than that of the fish fed diets containing the same protein concentrations with typical DE:P ratios. At a DE:P ratio of 8.5 kcal/g protein, there were no differences in fillet fat concentration among fish fed diets containing different protein concentrations. There were no differences in fillet protein, moisture, and ash between fish fed the 24% or 28% protein diets containing reduced and typical DE:P ratios. Results from this study show that reducing DE:P ratios in practical diets lowers body fat but also depresses weight gain of channel catfish; thus it would not be economical to use this strategy to reduce body fat of the fish.     

A Comparative Study of the Dietary Lysine Requirement of Juvenile Striped bass Morone saxatilis and Sunshine bass M. chrysops x M. saxatilis

Previous reports have indicated there are significant differences in both the dietary lysine requirement and the metabolic rate of striped bass and its hybrids. However, there is very little directly comparative data to confirm these suggestions. A series of experiments was conducted to comparatively assess efficiency of protein and energy retention between striped bass Morone saxatilis and sunshine bass M. chrysops♀×M. saxatilis♂ grown under identical culture conditions. In experiment one, a dose response study was conducted using digestible energy (DE) levels of 3,200 kcal/kg and 3,600 kcal/kg. At each level of DE, six levels of dietary lysine were fed to striped bass and sunshine bass. Ten sunshine bass weighing 3.48 ± 0.08 g or six striped bass weighing 3.23 ± 0.14 g were stocked into 15-L tanks supplied with single-pass flow-through fresh water. After 12 wk on the experimental regime, feed conversion ratios (FCR), weight gain, and % nitrogen (N) retention were determined. Nonlinear regression analysis indicated that the dietary lysine requirement of both bass groups was similar. The dietary lysine requirement was determined to be 2.0 ± 0.08% of dry diet (or 6.0 ± 0.26 g lysine/1,000 kcal DE), and 1.7 ± 0.08% of dry diet (or 4.7 ± 0.22 g lysine/1,000 kcal DE), for the 3,200 and 3,600 kcal DE/kg diets, respectively. A second experiment comparatively assessed growth, metabolism, and energy partitioning between striped bass and sunshine bass. Two diets were formulated to be isonitrogenous and isocaloric with a calculated DE level of 3462 kcal/kg and contained lysine concentrations approximating the published dietary requirements of sunshine bass (low lysine = LL diet) and striped bass (high lysine = HL diet). The diets were fed at an average rate of 2% of body weight/d to 25 juvenile striped bass or hybrid bass held separately in eight 2000-L single-pass flow-through tanks supplied with freshwater. In general, growth performance of sunshine bass was superior to striped bass. Both bass groups performed better when fed the HL diet. Mean FCRs were 1.19 ± 0.12 and 1.94 ± 0.29, respectively, for hybrids and striped bass fed the LL diet (P= 0.066); and 1.17 ± 0.07, and 1-58 ± 0.08, respectively, for hybrids and striped bass fed the HL diet (P = 0.011). Mean % gain/d values were significantly higher (P= 0.001) for hybrids (2.77 ± 0.85) than for striped bass (1-30 ± 0.27) when fed the LL diet. When fed the HL diet, mean % gain/d was significantly higher (P = 0.003) for sunshine bass (2.72 ± 0.83) compared to striped bass (1.51 ± 0.25). Additionally, when fed the HL diet, sunshine bass had significantly higher percent nitrogen (P= 0.006) and energy retention (P= 0.014) when compared to striped bass. These results further document that sunshine bass are more efficient at protein and energy retention compared to striped bass in freshwater.     

Effect of different dietary protein and lipid levels on growth and survival of juvenile Australian redclaw crayfish, Cherax quadricarinatus (von Martens)

This study determined the effect of different dietary protein and lipid levels on growth and survival of juvenile redclaw Cherax quadricarinatus. Nine practical test diets were formulated to contain three crude protein (CP) levels [260, 310 and 360 g kg^?1, equivalent to 225, 260 and 296 g kg^?1 digestible protein (DP) respectively] at three crude lipid (CL) levels (40, 80 and 120 g kg^?1, equivalent to 38, 67 and 103 digestible lipids respectively), with digestible protein : digestible energy (DP : DE) ranging from 14.6 to 22.6 mg protein kJ g^?1. Three replicate groups of 15 crayfish (initial weight mean ± SD, 0.71 ± 0.13 g) per diet treatment were stocked in 40 L tanks, at 28 °C for 60 days. The highest mean weight, specific growth rate and biomass, with values of 7.0 g, 3.67% day^?1, and 370.2 g m^?2, respectively, were achieved by feeding a diet with P : L = 310 : 80 (P < 0.05). The treatments resulted in a survival rate of 80–91%, feed conversion ratio of 1.08–1.61 and protein efficiency ratio of 2.24–3.08. Results indicated that a diet containing 270 g kg^?1 DP (equivalent to 320 g kg^?1 CP), 75 g kg^?1 digestible lipid (DL) with a DP/DE of 18.4 mg protein kJ^?1, and 0.031 g protein per animal per day was optimum for juvenile C. quadricarinatus under the tested experimental conditions.     

Effects of variable feed allowance with constant energy and ratio of energy to protein in a diet for constant protein input on the growth of common carp Cyprinus carpio L.

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.     

Diet formulation for Macrobrachium rosenbergii (de Man) broodstock based on essential amino acid profile of its eggs

Twelve pelleted diets containing a range of protein and energy levels from 30% protein, 400 kcal gross energy per 100 g diet to 40% protein and 520 kcal gross energy per 100 g diet were formulated. A least-cost linear programming package was applied to determine the optimum inclusion levels of some locally available ingredients. The essential amino acid constraints applied to the diets were based on the essential amino acid content of the eggs of broodstock Macrobrachium rosenbergii (de Man). The study was undertaken using 13 one-tonne capacity fibreglass tanks, each with a water recycling system. Each tank was partitioned into three equal compartments by nylon netting; each compartment was stocked with six female and one male prawn which were fed with the various diets at 2% body weight daily split into three feedings at 0800, 1200 and 1800 h. The results indicated that prawn fed the 40% protein diet with an energy level of 400 kcal per 100 g diet attained the highest fecundity, producing 1355 eggs per gram body weight, followed by those fed P40 with a gross energy level of 440 kcal 100 g^-1 (1354 eggs per gram body weight), and prawns fed control diet (30% protein with an energy level of 442 kcal 100 g diet^-1) attained the lowest fecundity (1080 eggs per gram body weight). However, statistically, no significant differences in fecundity were observed among prawn fed 35% protein diet with an energy level of 473 kcal 100 g^-1, 40 with energy levels of 400 or 440 kcal 100 g diet^-1. The essential amino acids index (EAAI) were calculated and were found to be a possible method of evaluating the broodstock diet of M. rosenbergii as a higher index indicates higher egg production. Therefore, a diet containing 40% protein, with an energy level of 400 kcal 100 g diet^-1 is recommended as a broodstock feed for M. rosenbergii in view of its superior performance and cost.     

Effects of dietary vitamin E level on growth and tissue lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis (Wiegmann)

A feeding trial was conducted to determine the effect of dietary vitamin E supplementation on growth, liver lipid peroxidation and liver and muscle vitamin E level of soft‐shelled turtle, Pelodiscus sinensis. Eight experimental diets analysed to contain 0–457 IU vitamin E kg^?1 were fed to juvenile soft‐shelled turtle of 4.8 g initial body weight for 12 weeks. Weight gain (WG) of the turtles fed the diet containing no vitamin E was significantly lower than those fed diets containing 83–457 IU vitamin E kg^?1 (P<0.05). Feed conversion ratio and protein efficiency ratio showed similar trends to that of WG. No significant difference (P>0.05) was found in whole‐body composition among turtles fed the different diets. Dietary vitamin E requirement using WG as the response and estimated using the broken‐line regression model is approximately 88 IU kg^?1. Liver and muscle vitamin E content increased when dietary vitamin E level increased. Ascorbate‐induced lipid peroxidation in liver tissue of turtles fed diets containing 0 and 17 IU vitamin E kg^?1 was significantly (P<0.05) greater than those fed diets containing high vitamin E (≥35 IU kg^?1).     

Effects of dietary protein and lipid levels and protein to energy ratios on growth performance and feed utilization of hatchery-reared juvenile spotted babylon (<Emphasis Type="Italic">Babylonia areolata</Emphasis>)

A 120-day feeding trial was designed to determine the effects of different dietary protein and lipid levels and protein to energy ratio (P:E) on growth performance and feed utilization of hatchery-reared juvenile spotted babylon, Babylonia areolata, cultured under a flow-through seawater system. Six diets were formulated to contain three protein levels (18, 28, and 36%) and two lipid levels (10 and 15%) in a 3 × 2 factorial design with three replicates to provide six different dietary P:E ratios (50.17, 49.09, 68.50, 65.85, 88.66, and 85.36 mg protein/kcal). Each replicate was stocked with 50 snails (0.12 + 0.01 g, initial weight) and fed to satiation once daily. The results showed that survival was above 96% at the end of the feeding trial in all groups and was not affected by either dietary protein level or dietary lipid level. The highest significant (P < 0.05) growth and feed utilization were observed for juveniles fed diet with a P:E ratio of 88.66 kcal g⁻¹ diet. With respect to dietary protein and lipid levels, the highest (P < 0.05) values for growth and feed efficiency were observed for snails fed a diet containing 36% protein level and the same trend was observed for snails fed a diet with 10% lipid level. This results indicated that the diet containing 36% protein and 10% lipid level with a dietary P:E ratio of 88.66 mg protein/kcal would be suitable for optimum growth and feed utilization of B. areolata juveniles.     

The effects of partial replacement of white fish meal by poultry by-product meal and addition of bile acid in feed on growth,digestibility, and serum enzyme activities of the Chinese soft-shelled turtle

Four isonitrogenous experimental diets were used to test the effects of replacing white fish meal with poultry by-product meal (PBM) and adding bile acid (BA) in a commercial feed for the Chinese soft-shelled turtle Pelodiscus sinensis with 9 replicates and 6 turtles in a 60-day study. Diet 1 contained white fish meal as a main protein source (100 %). Diet 2 contained white fish meal (60.8 %) and PBM (39.2 %) as the protein source. Diets 3 and 4 comprised the addition of 1 g kg^?1 of bile acid to diets 1 and 2, respectively. Compared to diet 1, the glutamic-pyruvic transaminase level in the turtles fed with diet 2 were not augmented significantly as was the case for glutamic oxalacetic transaminase level. The relative growth rate and specific growth rate in diet 2 were the same as those of diet 1. The apparent digestibility coefficient for lipid (ADCL) tended to decrease after that white fish meal was partially replaced. The values of weight gain, relative growth rate, feeding rate, specific growth rate, apparent digestibility coefficient for dry matter, ADCL and apparent digestibility coefficient for protein (ADCP) of the turtles on diet 4 (1 g kg^?1 bile acid added in diet 2) increased by 28.1, 28.8, 10.1, 20.6, 1.7, 0.6 and 0.3 %, respectively, compared to those on diet 2. The combined effects of bile acid and PBM on the growth of turtles was even more effective than the whole white fish meal diet, by increasing feeding rate 7.4 %; it decreased the amounts of crude lipids (by 22.8 %), glutamic-pyruvic transaminase (by 1.9 %), and alkaline phosphatase (by 3.9 %). Therefore, replacing 39.2 % of white fish meal with PBM and adding BA was feasible in turtle feed.     

Effect of protein to energy ratio in purified diets on growth performance, feed utilization and body composition of Mozambique tilapia, Oreochromis mossambicus (Peters)

A 3 × 3 factorial experiment was conducted with Mozambique tilapia. Oreochromis mossambicus (Peters), using satiate feeding with 25%, 30% or 35% dietary protein concentrations each with three energy concentrations 10.5,12.6 or 14.7 kJ per g of purified diets. Protein-to-energy ratios (P/DE ratio) ranged from 17 to 33.4 mg protein kJ^?1 of digestible energy (DE). Diets were fed to triplicate random groups of 15 fingerlings for 62 days in glass aquaria. Improvement in both weight gain and feed conversion rate (FCR) was achieved when dietary protein increased (P < 0.05), while increasing dietary energy concentration reduced feed consumption and increased mortality (P < 0.05). Protein efficiency ratio (PER) increased as dietary protein decreased and as dietary energy increased (P < 0.05). P/DE ratio correlated positively with gain, energy retention (ER) and feed consumption (r= 0.96,0.96 and 0.73 respectively) and negatively with feed conversion rate (FCR), protein productive value (PPV), protein efficiency ratio (PER) and mortality (r= -0.93, -0.95. -0.91 and -0.84 respectively). Weight gain had a positive relation with feed consumption (r= 0.82). The optimum P/DE ratio in purified diets for Mozambique tilapia for rapid growth, efficient feed conversion and maximum retention of protein and energy appears to be approximately 23.8 mg of protein kJ^?1 of DE.     

Effect of Dietary Protein Concentration on Growth and Processing Yield of Channel Catfish Ictalurus punctatus1

Abstract.— This study was conducted to evaluate the effect of dietary protein concentration and an all‐plant diet on growth and processing yield of pond‐raised channel catfish Ictalurus punctatus. Four diets were formulated using plant and animal proteins to contain 24%n, 28%, 32%, or 36% crude protein with digestible energy to protein (DE/P) ratios of 11.7, 10.2, 9.0, and 8.1 kcal/g, respectively. An all‐plant diet containing 28% protein with a DE/P ratio of 10.2 kcal/g was also included. Channel catfish fingerlings averaging 40 g/fish were stocked into 24, 0.04‐ha ponds at a density of 18,530 fish/ha. Five ponds were used for each dietary treatment except for the all‐plant diet which had four replicates. The fish were fed once daily to apparent satiation for 160 d. No differences were observed in feed consumption, weight gain, survival, carcass and nugget yield, or fillet moisture and protein concentrations among treatments. Fish fed the 28% protein diet had a lower feed conversion ratio (FCR) than fish fed diets containing 24% and 32% protein, but had a FCR similar to fish fed the 36% protein diet. Fillet yield was higher for fish fed the 36% protein diet than fish fed the 24% protein diet. Visceral fat was lower in fish fed the 36% protein diet than fish fed other diets. Fish fed the 32% and 36% protein diets exhibited a lower level of fillet fat than fish fed the 24% protein diet. The 36% protein diet resulted in a lower level of fillet fat than fish fed the 28% protein diet. There was a positive linear regression in fillet yield and fillet moisture concentration and a negative linear regression in visceral fat and fillet fat against dietary protein concentration. No differences in any variables were noted between the 28% protein diets with and without animal protein except that fish fed the 28% protein diet without animal protein had a higher FCR than fish fed the 28% protein diet with animal protein. This observation did not appear to be diet related since FCR of fish fed the 32% protein diet containing animal protein was not different from that of fish fed the 28% all‐plant protein diet. Data from the present study indicate that dietary protein concentrations ranging from 24% to 36% provided for similar feed consumption, growth, feed efficiency, and carcass yield. However, since there is a general increase in fattiness and a decrease in fillet yield as the dietary protein concentration decreases or DEP ratio increases, it is suggested that a minimum of 28% dietary protein with a maximum DEIP ratio of 10 kcal/g protein is optimal for channel catfish growout.     

Effects of Protein and Lipid Levels in Practical Diets on Growth and Body Composition of Tongue Sole,Cynoglossus semilaevis Gunther

A 9‐wk feeding experiment was conducted to estimate the optimal dietary protein and lipid levels for tongue sole, Cynoglossus semilaevis Gunther (initial average weight of 43.8 ± 0.18 g). Six practical test diets were formulated to contain three protein levels (45, 50, and 55%, respectively) at two lipid levels (12 and 16%, respectively) with P/E ratios ranging from 87.1 to 110.5 mg protein/kcal. Each diet was randomly fed to triplicate groups of 20 fish per tank (1000 L). The results showed that fish fed the diet with 55% protein and 12% lipid (P/E ratio of 110.5 mg protein/kcal) had the highest thermal‐unit growth coefficient (TGC), feed efficiency ratio, protein productive value, and energy retention. TGC was significantly increased with increasing dietary protein levels irrespective of dietary lipid levels (P < 0.05). However, fish fed the diet with 16% lipid showed significant lower growth than fish fed the diet with 12% lipid. These results suggest that the diet containing 55% protein and 12% lipid with P/E of 110.5 mg protein/kcal is optimal for tongue sole and the increase of dietary lipid level has no effective protein‐sparing effect.     

Partial replacement of fish meal by soy protein concentrates in diets for a new Japanese strain of juvenile soft‐shelled turtle,Pelodiscus sinensis

An 8‐week experiment was conducted to evaluate the effects of dietary fish meal (FM) replaced by soybean protein concentrate (SPC) on Japanese strain of soft‐shelled turtle, Pelodiscus sinensis juveniles. Diets were formulated to replace FM protein by SPC at 0, 15, 30, 45, 60 or 60% supplemented with phytase (2000 FTU kg^?1) (designated as S0, S15, S30, S45, S60 and S60P, respectively), and each diet was fed to triplicate groups. The results showed that the growth was significantly lower when dietary SPC replaced more than 45% FM. The turtles fed the S15 or S30 diet showed comparable feed and protein utilization efficiency compared with the S0 group, whereas more than 30% replacement of FM adversely affected these values. Increasing dietary SPC levels significantly lowered the apparent digestibility coefficients (ADC) of dry matter, protein, lipid, phosphorus and gross energy. Whole‐body protein, ash and phosphorus content showed a declining trend when dietary SPC levels increased, while body lipid and moisture content were unaffected. When the turtles were fed diets with increasing levels of SPC, serum total protein concentration, alkaline phosphatase and catalase activities decreased with a corresponding increase in glutamic pyruvic transaminase activity. Turtles fed the S60P diet showed comparable growth performance and feed utilization efficiency to the S40 group, and were superior to the S60 group. The present study showed that SPC could successfully substitute for 30% FM protein in the diets for P. sinensis juveniles, and the maximum effective substitution may be greater if exogenous phytase was added.     

Effect of dietary calcium and phosphorus supplementation in fish meal-based diets on the growth of soft-shelled turtle Pelodiscus sinensis (Wiegmann)

A growth experiment was conducted to determine the effect of supplementing dietary calcium in fish meal‐based diets on the growth of cultured soft‐shelled turtle Pelodiscus sinensis. Juvenile soft‐shelled turtles of 4.1 g mean body weight were fed nine diets containing two levels of phosphorus (2.7% or 3.0%) and analysed calcium levels ranging from 4.7% to 6.6% for 10 weeks. The growth of the turtles was enhanced when inorganic calcium was added to the diets. The weight gain of the turtles fed the control diet containing calcium solely from fish meal was the lowest among the test groups, and was significantly lower than those fed the diet containing 5.7% calcium at the 3.0% phosphorus level (P<0.05). Feed conversion and protein efficiency ratios were not affected by different dietary treatments. Whole‐body moisture and crude protein contents of turtles were not affected by different dietary treatments. The body ash of turtles fed 3.0% phosphorus diets tended to be higher than turtles fed 2.7% phosphorus diets. The body calcium to phosphorus ratio of turtles fed 3.0% phosphorus diets was greater than that of turtles fed diets containing 2.7% phosphorus. Supplementation of Ca in a fish meal‐based practical diet is required for the optimum growth of soft‐shelled turtles.     

Replacing fish meal with increasing levels of meat and bone meal,soybean meal and corn gluten meal,in diets of juvenile bluegill,Lepomis macrochirus

A 60‐day study was conducted to determine the response of juvenile bluegill Lepomis macrochirus to seven experimental diets, formulated using a blend of alternative protein sources as a replacement for fish meal. Adequate levels (digestible basis) of energy, protein and amino acids were maintained in diets 1–6, whereas slightly lower protein and energy levels were provided in diet 7. Feed cost per tonne ranged from $ 798.9 (diet 1, 550 g Kg^?1 fish meal) to $ 515.8 (diet 6, 0 g kg^?1 fish meal), or to $ 507.2 (diet 7, 0 g Kg^?1 fish meal). Three commercial diets were included in the study as reference diets: a high‐energy and a low‐energy trout diet, as well as a catfish diet. Quintuplicate bluegill groups (~22 g, n = 10 fish group^?1) were fed the experimental diets twice daily to apparent satiation. No major differences in feed consumption, feed efficiency and growth rates were detected among the bluegill groups fed the experimental diets. Trout diets generally produced higher fish fat deposition, whereas the catfish diet produced a poorer fish growth rate relative to the experimental diets. Under the reported conditions, results indicate diet 6, comprising predominantly soybean meal and porcine meat and bone meal, to be the most economical diet for juvenile bluegill.     

Pond production of Pacific white shrimp,Litopenaeus vannamei,fed grain distillers dried yeast

The objective of this study was to demonstrate the feasibility of four diets formulated to contain increasing levels (0, 50, 100 and 150 g kg^?1 of diet) of grain distillers dried yeast (GDDY) in production diets for Litopenaeus vannamei, reared in outdoor tanks or production ponds. The production pond trial was carried out in 16, 0.1‐ha ponds using four replicates per diet. Juvenile shrimp (38.1 ± 4.26 mg, initial weight) were stocked at 30 shrimp m^?2 for a 16‐week period. The same four diets and a commercial reference diet were offered to shrimp maintained in outdoor tanks over a 12‐week period. A total of 20 tanks were stocked with juvenile shrimp (3.05 ± 0.22 g, initial weight) obtained from production ponds at a density of 30 shrimp per tank (40 shrimp m^?2). At the conclusion of these trials, mean final weight ranged from 19.77 to 23.05 g, yield ranged between 4760 and 5606 kg ha^?1, survival ranged from 69.6% to 89.4%, and feed conversion ratio (FCR) was between 1.02 and 1.23. Shrimp reared in the outdoor tanks confirmed the results of the pond trial. Mean final weight ranged between 18.12 and 18.97 g, survival ranged from 93.3% to 98.3%, and FCR was between 1.25 and 1.29. In both trials, there were no significant differences regarding mean final weight, FCR and survival among dietary treatments. Based on this study, GDDY up to 150 g kg^?1 of diet can be used in L. vannamei commercial feed formulation.     

Evaluation of ultra‐low gossypol cottonseed and regular glandless cottonseed meals as dietary protein and lipid sources for Litopenaeus vannamei reared under zero‐exchange conditions

The current study evaluated transgenic cotton lines with normal levels of gossypol/terpenoids in the vegetative and floral tissues, but with ultra‐low gossypol in the seeds as a replacement for glandless cottonseed meal (GCSM) and fishmeal. A 64‐day growth trial evaluated the ability of cottonseed meals from a natural glandless cotton variety/mutant, two transgenic Ultra‐low Gossypol Cottonseed (ULGCS) lines, a non‐transgenic parental control and a commercial variety, to replace 355 g kg^?1 fishmeal in a diet containing 350 g kg^?1 crude protein. Juvenile Litopenaeus vannamei (1.48 ± 0.29 g) were stocked (40 shrimp m^?3) with six replicates. No significant differences were found between all formulated diets in terms of final weight, survival and feed conversion ratio. The commercial cottonseed variety displayed a significantly lower feed efficiency ratio and protein efficiency ratio than one of the ULGCS diets. These results suggest that GCSM and/or transgenic ULGCS meals can be used to replace fishmeal in commercial shrimp diets.     

Assessing the efficacy of three methionine sources in low protein and low fish meal diet for Chinese soft-shelled turtle, <Emphasis Type="Italic">Pelodiscus sinensis</Emphasis>

An 8-week feeding trial was conducted to evaluate the effects of three dietary methionine (Met) sources [dl-Met, coated-Met, and a methionine hydroxy analogue calcium salt (MHA-Ca)] for Chinese soft-shelled turtle (Pelodiscus sinensis). Triplicate groups of juvenile turtles (initial weight 3.48 ± 0.03 g) were fed twice per day at 3% of body weight with positive control diet (T1, 46% protein and 46% fish meal, FM), negative control diet (T2, 43% protein and 23% FM), or three other test diets supplemented with either 0.2% coated-Met (T3), 0.125% MHA-Ca (T4), or 0.1% dl-Met (T5) to the T2 basal formulation, respectively. The feeding trial was conducted in 15 350-L plastic containers with three replicates per dietary treatment. The results showed that the highest and lowest percentage weight gain (1023.5 ± 18.2 versus 882.1 ± 14.5%) and feed efficiency (87.2 ± 0.94 versus 81.4 ± 0.4%) were observed in turtles fed the T1 and T2 diet (P < 0.05), respectively. Significant improvement in weight gain was observed in turtles fed diets with Met supplementation, irrespective of source, compared with turtles fed the T2 diet. It was observed that dietary MHA-Ca had similar efficacy compared with dl-Met in terms of growth performance and feed utilization efficiency of the turtles (P > 0.05). Protein utilization efficiency was significantly higher in turtles fed T4 or T5 diet compared to the T2 diet. Whole body protein content (17.0 to 17.4% on a wet weight basis) in turtles fed with Met-added diets was comparable to those of turtles fed the T1 diet which were significantly higher compared to T2-fed turtles. Antioxidant defense system enzymes, superoxide dismutase, and glutathione peroxidase showed the highest activity, 658.8 ± 17.9 U/mL and 642.8 ± 17.5 μmol/L, respectively, in the serum of turtle fed the MHA-Ca supplemented diet and was significantly higher compared to turtles fed the T2 or T3 diet. The present results showed that P. sinensis are able to effectively use added MHA-Ca and dl-Met in low protein and low FM diets to enhance growth, feed utilization efficiency, nitrogen retention, and antioxidant defense system enzyme activities.     

Optimum digestible protein and energy levels and ratio for greater amberjack Seriola dumerili (Risso) fingerling

A study was conducted to determine optimum dietary digestible protein (DP) and digestible energy (DE) levels and DP DE⁻¹ ratio for growth of greater amberjack Seriola dumerili fingerlings. A 3 × 3 factorial design with duplication was used in this study. Nine experimental diets were formulated to contain three levels of crude protein (CP; 420, 470 and 530 g kg⁻¹) and three levels of crude lipid (CL; 130, 180 and 230 g kg⁻¹). Nine groups of fingerling (initial weight 51.8 g) were fed each experimental diet for 40 days. Final body weight, feed efficiency, specific growth rate and energy efficiency were significantly affected by dietary protein and lipid level. These parameters tended to improve with increasing dietary protein level. Conversely, an increase of lipid level negatively affected these parameters. High growth rate and feed efficiency were obtained from fish fed the diet containing 393 g kg⁻¹ DP and 14.2 MJ kg⁻¹ DE (27.7 g MJ⁻¹ DP DE⁻¹). The high DP DE⁻¹ (27.7 g MJ⁻¹) indicates that greater amberjack fingerling are highly dependent on dietary protein as an energy source.     

Evaluation of practical diets containing various terrestrial protein sources on survival and growth parameters of redclaw crayfish Cherax quadricarinatus

Redclaw aquaculture has developed at a rapid pace during the past few years, yet no specialized diet for the species has been developed. The present study was designed to evaluate whether soybean‐based diets containing either fishmeal (FM), poultry by‐product meal (PBM), ground peameal (GPM) or distillers dried grains with solubles (DDGS) meal as a protein source are suitable for redclaw aquaculture. Juvenile redclaw crayfish Cherax quadricarinatus (0.125±0.025 g) were stocked into 20 rectangular tanks at a stocking density of 12.5 m^?2 for 8 weeks. Crayfish in four replicate tanks were maintained on one of five diets formulated to contain 35% crude protein and 7.1% lipids. Each 100 g of diet contained 25 g of protein from soybean meal (SBM) and 10 g of protein from the alternative protein sources mentioned above. A fifth treatment that did not receive feed was included to account for growth from natural productivity. There were no significant differences in survival (86–90%), growth (3.84–4.98 g animal^?1) or feed conversion ratio (2.10–2.79) of crayfish among the four treatments (P>0.05). Survival and growth of crayfish in the treatment that received no supplementary feed were significantly less than those in treatments offered experimental diets. Results of the present experiment suggest that SBM‐based diets with PBM, FM, DDGS or GPM have similar effects on growth performance and survival of juvenile redclaw, C. quadricarinatus.