Effects of vitamin A inclusion in practical diets on survival and growth of juvenile crayfish (Pacifastacus leniusculus Dana,Astacidae) from the onset of exogenous feeding

The aim of this study was to evaluate the effects of practical diets with different levels of vitamin A on survival and growth of juvenile crayfish (Pacifastacus leniusculus). An 80‐day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four diets differing in the level of retinyl acetate were tested: 0, 0.0025, 0.0050 or 0.0100 g kg^?1 diet, equivalent to 0, 2500, 5000 or 10 000 IU vitamin A kg^?1 diet, respectively. Each diet was tested on grouped or individually isolated crayfish. Crayfish fed the diet with 5000 or 10 000 IU vitamin A kg^?1 diet achieved the highest survival (average of grouped and isolated: 88.9%) and growth (grouped and isolated: 13.45 mm carapace length, 533.4 mg weight). Final growth of isolated crayfish was significantly higher than that of grouped crayfish for all diets. This study provides the first data on vitamin A requirements of freshwater crayfish. A level of 5000 IU vitamin A kg^?1 can be recommended for juvenile P. leniusculus during the first period of intensive rearing.     

Effects of vitamin C inclusion in practical diets on survival and growth of juvenile crayfish (Pacifastacus leniusculus Dana,Astacidae) from the onset of exogenous feeding

The aim of this study was to evaluate the effects of practical diets with different levels of vitamin C on survival and growth of juvenile crayfish (Pacifastacus leniusculus). An 80‐day trial was conducted with stage 2 juveniles from the onset of exogenous feeding. Four practical diets differing in the content of l ‐ascorbyl‐2‐monophosphate‐Na were prepared: 0, 0.2, 0.4 or 0.8 g kg^?1 diet. Each diet was tested on grouped or individually isolated crayfish. Diets had no significant effects on survival of crayfish held in groups (average: 73.1%) neither on the isolated ones (average: 90%). Crayfish fed the diet with 0.2 g kg^?1 of l ‐ascorbyl‐2‐monophosphate‐Na had the highest growth (groups: 13.64 mm carapace length (CL), 542.4 mg weight; isolated: 17.05 mm CL, 1213.2 mg weight) and the lowest feed conversion ratio (average of grouped and isolated: 0.99). This study provides the first data on vitamin C requirements of freshwater crayfish. A level of 0.2 g l ‐ascorbyl‐2‐monophosphate‐Na kg^?1 diet (0.07 g ascorbic acid equivalent) can be recommended for juvenile P. leniusculus during the first period of intensive rearing.     

Response of juvenile astacid crayfish (Pacifastacus leniusculus) to three commercial dry diets with different protein levels during the first 6 months of intensive rearing

A 180‐day experiment was carried out under controlled conditions to compare the effects of three commercial dry diets on survival, growth and body composition of juvenile Pacifastacus leniusculus from the onset of exogenous feeding (stage 2). Protein levels in the diets were 55.5% [high‐protein content (HP) diet], 40.3% [medium‐protein content (MP)] and 33.2% [low‐protein content (LP)]. Diets were supplemented with restricted amounts of live fresh Artemia nauplii up to day 120. No significant differences in survival among diets were found along the trial, with final values around 68.5%. During the live feed supplementation, growth was similar with the three diets. At the end of the trial, weight with HP or with MP was similar (around 2.32 g) and significantly higher than with LP (1.97 g). Thus, a diet with 40% of protein can be suitable, as it allowed similar results as the diet containing 55%. Levels of protein in diets and in crayfish muscle were positively correlated (r=0.8). This study also shows that an intensive rearing up to 180 days with good survival and growth rates is possible using dry diets for finfish species supplemented with live feed.     

Intensive rearing of juvenile crayfish (Pacifastacus leniusculus,Astacidae) during the first 6 months: effects of size grading

Recent advances in crayfish feeding have enabled the development of size grading studies from the start of first‐feeding. A 180‐day experiment aimed at intensive rearing of Pacifastacus leniusculus was carried out under controlled conditions, evaluating the effects of size grading at two different periods from the onset of exogenous feeding. Stage 2 juveniles were stocked in fibreglass tanks at a density of 100 m², and fed a dry diet for salmonids combined with restricted amounts of Artemia cysts. Five groups were tested: no grading, grading at 60 days (large and small size) and grading at 100 days (large and small size). After 6 months, no significant differences were found in the survival among groups (mean: 73.06%). The highest final growth (pooled results from upper and lower classes: 17.39 mm carapace length, 1.43 g weight) was achieved by the crayfish sorted at 60 days, showing significant differences from the ungraded group. Smaller crayfish graded at 60 days grew significantly faster than smaller crayfish graded at 100 days. The food conversion ratio was lower in the graded groups (mean: 2.64), showing significant differences from the ungraded group (3.23). This study shows that size grading allows a better performance and an improved feeding efficiency.     

Shelter and lighting in the intensive rearing of juvenile crayfish (Pacifastacus leniusculus,Astacidae) from the onset of exogenous feeding

Recent advances on feeding in intensive rearing of juvenile astacids enable research of other factors influencing growth and survival without the confounding effect of inadequate feeding. Two experiments were conducted to evaluate the effects of the number of shelters per crayfish and to test different lighting conditions. Stage 2 juvenile Pacifastacus leniusculus were stocked in fibreglass tanks and fed a dry diet for salmonids combined with restricted amounts of decapsulated Artemia cysts. In experiment 1, four, two or one shelters per crayfish were tested for 80 days. No significant differences were found among groups either in survival (final mean: 86.67%) or in growth [final mean: 11.41 mm mean carapace length (CL), 355.45 mg mean weight]. In experiment 2, three lighting conditions were tested for 120 days: continuous lighting of 925 lx, continuous darkness and natural photoperiod. Survival rates ranged from 76.7% to 88.3%, with no significant differences among groups. The crayfish kept under continuous darkness grew faster (final mean: 12.70 mm CL, 543.08 mg weight) than those reared under the other two light conditions. This study shows that, under improved feeding conditions, a minimum number of shelters can be provided, and faster growth can be obtained in continuous darkness.     

Replacement of fish meal with poultry by-product meal in practical diets for redclaw crayfish (Cherax quadricarinatus)

Aquaculture of redclaw crayfish, Cherax quadricarinatus, is rapidly developing in tropical and sub‐tropical regions of the world. As the industry is still in its infancy, grow out diets are generally not formulated specifically for this species as there is limited data on nutrient requirements and the acceptability of various ingredients. Given the recent increases in the price of fish meal (FM), the use of alternative protein sources such as poultry by‐product meal (PBM) may be more cost effective. The present research evaluated the response of juvenile redclaw to practical diets utilizing PBM as a replacement for FM. Juvenile redclaw crayfish (0.45 g ± 0.01) were stocked into 24, 600‐L, outdoor round tanks at a density of 12.5 m^?2. Tanks were supplied water from a watershed reservoir and maintained on a flow through regime. Crayfish in four replicate tanks were maintained on one of the six diets formulated to contain 260 g kg^?1 crude protein and 70 g kg^?1 crude fat which had previously demonstrated good growth under similar conditions. FM in the basal diets was replaced with PBM at various levels, on an iso‐nitrogenous basis, so that the diets contained 150, 120, 90, 60, 30 and 0 g FM kg^?1 diet and 78, 105, 132, 158, 185 and 212 g PBM kg^?1 diet, respectively. At the conclusion of the 56‐day growth trial, survival (>83%) and growth (>11.3 g or 2400%) of the crayfish were not significantly different among treatments. Based on these results, PBM appears to be a viable candidate as a replacement for FM in redclaw crayfish diets.     

Evaluation of poultry by‐product meal as partial replacement of fish meal in practical diets for juvenile tench (Tinca tinca L.)

The aim of this study was to evaluate different replacement levels of fish meal (FM) by poultry by‐product meal (PBM) on survival, growth performance and body composition of juvenile tench (Tinca tinca). A 90‐day experiment was conducted with 5 month‐old juveniles (31.95 mm total length, 0.396 g weight). Eight practical diets (50% crude protein) differing in the level of replacement of FM protein by PMB protein were tested: 0% (control), 25%, 31%, 37%, 43%, 49%, 55% and 61% corresponding to 0, 184.8, 229.2, 273.5, 317.8, 362.1, 406.5 or 450.8 g PBM kg^?1 diet respectively. Significant differences were not found (P > 0.05) between 25% replacement of FM protein by PBM protein (184.8 g kg^?1 PBM in diet) and control diet. At higher replacement levels, fish had significantly lower growth, higher feed conversion ratio and lower protein productive value (P < 0.05). Fish with externally visible deformities ranged from 1.1% to 3.3%. The relation among amino acid profiles of the diets, body composition, growth performance of juveniles and amino acid requirements of other fish species is discussed. Up to 184.8 g PBM kg^?1 diet can be included in diets for juvenile tench without impairing growth performance.     

Partial replacement of fishmeal by fermented soybean meal in diets for juvenile white shrimp (Litopenaeus vannamei)

As an important feed ingredient, fermented soybean meal (FSM) has been widely used in aquatic animals due to its stable sources and reasonable price. Here, we evaluated the potential for replacement of fishmeal (FM) with FSM in diet of Litopenaeus vannamei. Five isonitrogenous (410 g/kg) and isolipidic (80 g/kg) diets were formulated: a control diet containing 320 g/kg FM and four experimental diets in which FM in control diet was replaced by FSM at 10 (FSM10%), 20 (FSM20%), 30 (FSM30%) and 40% (FSM40%). An 8‐week feeding trial was conducted in fifteen fibreglass tanks with 50 shrimps per tank. After 8 weeks trial, FSM20% had significantly enhanced growth performance (p < 0.05). No significant difference was found in body composition and digestive enzyme activities of all groups (p > 0.05). Through real‐time quantitative PCR analysis, tor and s6k expression levels of FSM20% were significantly up‐regulated (p < 0.05). Results of western blot showed that the phosphorylation of S6K was not significantly affected by different dietary treatments (p > 0.05), which suggested mTOR signalling pathway was not affected by FSM diets. Based on the above data, 20% replacement of FM with FSM was reasonable and advantageous for L. vannamei diet.     

Effects of breeder reuse on the reproductive potential of the signal crayfish (<Emphasis Type="Italic">Pacifastacus leniusculus</Emphasis> Dana. Astacidae) in culture

The aim of this work was to evaluate the reproductive potential of the signal crayfish (Pacifastacus leniusculus Dana) in the second cycle under culture conditions. The experiment was carried out using 5,653 animals placed in six earthen ponds in August. Three treatments were performed, each in two ponds: breeder reuse (males and females used in the former reproductive cycle), female reuse (new males from the wild and females used in the former reproductive cycle) and new breeders (males and females from the wild). In April, close to hatching, egg-bearing females were transferred to the hatchery. Mortality of the reused breeders (around 30% of females and 41.4% of males) was significantly higher than that of the new breeders (11.4% of females and around 19.5% of males). The proportion of berried females close to hatching was significantly higher for the new ones (77.4% of the initial number), and the percentage of new females with a large quantity of eggs (63.6%) was higher than that of the reused females (25.6 and 20.9%). Differences among the percentages of females without eggs in the new breeders (11.2%) and the rest of the treatments (30.7 and 39.6%) were significant. The reproductive capacity of reused females was not improved by providing new males. Considering the number of females initially stocked into ponds, mean yield per new female was greater than that of the reused females, mainly due to the higher mortality recorded in the reused broodstock. Although the yield that can be obtained using the same breeders in two reproductive cycles drops in the second one, the production was not negligible.     

Evaluation of pea protein concentrate as partial replacement of fish meal in practical diets for juvenile tench (Tinca tinca L.)

With the aim to evaluate different replacement levels of fish meal (FM) by pea protein concentrate (PPC) on survival, growth performance and body composition of juvenile tench (Tinca tinca), a 90‐day experiment was conducted with 6‐month‐old juveniles. Four practical diets (50% crude protein) differing in the level of replacement of FM protein by PPC protein were tested: 0% (control), 25%, 35% or 45%, corresponding to 0, 207.5, 290.4 or 373.3 g PPC kg^?1 diet respectively. Survival rates ranged from 96.4% to 98.5%. The 25% and 35% replacement diets resulted in similar growth values (P > 0.05) to those obtained with the control diet (average of the three feeding treatments: 57.57 mm total length, 2.48 g weight and 1.87% day^?1 specific growth rate). The 45% replacement diet had the lowest growth (P < 0.05). Fish with externally visible deformities ranged from 0% to 1.5%. The relation among amino acid profiles of the diets, body composition, growth performance of juveniles and amino acid requirements of other fish species is discussed. An amount of 290.4 g PPC kg^?1 diet (35% replacement of FM protein) can be included in juvenile tench diets without impairing growth performance.     

Effects of bottom substrate and presence of shelter in experimental tanks on growth and survival of signal crayfish, Pacifastacus leniusculus (Dana) juveniles

The effects of tank bottom substrates and presence of shelter on growth, survival and condition of cheliped in the juvenile (stage 2) signal crayfish, Pacifastacus leniusculus (Dana), with an initial stocking density of 200 individuals m^?2 were investigated. In the first trial, three different tank bottom substrates with or without shelter were used. The three bottom types were loose gravel, glued gravel and bare bottom. The fastest growth both in terms of wet weight and carapace length was observed on loose gravel bottom. Also survival (range 30.1% to 49.8%) was affected by bottom type being higher on gravel bottoms than on bare bottom. Shelter improved survival only on loose gravel bottom. Bottom type influenced also the number of animals with cheliped injuries. The highest proportion of animals with no injuries (59.5%) was found on bare bottom and the proportion was about 12% and 13% units less on loose gravel and on glued gravel bottom. The presence of shelter had a marginal probability in increasing the number of animals without injuries. In the second trial, the substitution of ordinary gravel as tank bottom substrate with crushed limestone was studied. The mean final wet weights were 0.517 g on ordinary gravel bottom and 0.481 g on limestone bottom. The survivals were about 74% and 80% respectively. Limestone bottom decreased marginally final wet weight, and increased survival but did not affect the final carapace length that had a mean value of 13.6 mm. We conclude from the present experiments that the type of tanks and the rearing system used supported good growth of juvenile signal crayfish. The best growth results could be obtained by using loose gravel (or loose limestone) on the bottom of the tanks with a sufficient quantity of hiding places. However, there appears to be an increased risk for cheliped injuries on bottoms with loose materials.     

Decapsulated Artemia cysts as dietary supplement for juvenile crayfish (Pacifastacus leniusculus, Astacidae) at different food supply frequencies from the onset of exogenous feeding under controlled conditions

Considering that the use of decapsulated Artemia cysts as direct food for juvenile crayfish could be an alternative to live nauplii, a 100-day experiment was carried out under controlled conditions to evaluate the effects of cysts, comparing with nauplii, as supplement to a dry diet for salmonids on the survival and growth of juvenile signal crayfish (Pacifastacus leniusculus) from the onset of exogenous feeding (stage 2). The reduction of feeding frequency was also tested. According to a bifactorial design, six treatments, differing in the supplement and feeding frequency, were tested: the dry diet supplemented with Artemia nauplii or decapsulated cysts was supplied once a day, once every two days and once every three days. Survival rates ranged from 56.7% to 81.7%, rising significantly with increasing the feeding frequency. The highest growth (12.94 mm carapace length and 593.08 mg weight) was reached by the crayfish that received the dry diet supplemented with cysts once a day, with significant differences from the rest of the treatments. Considering the supplement, the cysts supported significantly higher growth than the nauplii. Regarding the feeding frequency, growth was higher when the food was supplied once a day, showing significant differences from the other two frequencies (once every two days and once every three days). This study shows that decapsulated cysts are better dietary supplement than live nauplii. In crustacean culture, this is the first report of successful use of Artemia cysts from the onset of exogenous feeding.     

Effects of different bronopol treatments on final survival rates in the artificial incubation of crayfish eggs (Pacifastacus leniusculus,Astacidae)

Two experiments were conducted on the effects of bronopol in the artificial incubation of crayfish eggs (Pacifastacus leniusculus) with the aim to search an alternative to formaldehyde. In the first experiment, 50, 250, 500 and 1000 ppm bronopol and 3000 ppm formaldehyde (control) in periodical administrations were tested on a density of 6.6 eggs cm^?2. After 44 days of incubation, the highest survival was obtained with 1000 ppm bronopol (81.9% to stage 2 juvenile, with no significant difference from formaldehyde), whereas lower bronopol concentrations resulted in significantly lower survival. In the second experiment, 1000, 3000 and 5000 ppm bronopol and 3000 ppm formaldehyde (control) administered for 15 min every second day were tested on eggs at a density of 20 eggs cm^?2. After 78 days of incubation, bronopol at 3000 ppm allowed for a stage 2 juvenile survival rate of 65.0% (with no significant difference from formaldehyde), whereas significantly lower survival was obtained with 1000 ppm or 5000 ppm. This study shows that bronopol may constitute an alternative to formaldehyde in the artificial incubation of crayfish eggs. A concentration of 3000 ppm administered for 15 min every second day may be adequate even on long incubations at high densities (at least 20 eggs cm^?2, one complete layer).     

Hydrolysed salmon meal as a replacement for salmon meal in practical diets for Pacific white shrimp (Litopenaeus vannamei)

A series of growth, feed stability and consumption trials were conducted to evaluate the efficacy of salmon by‐product in practical diets for Pacific white shrimp, Litopenaeus vannamei. This included a salmon by‐product meal (Salmon meal: SM) and a silage hydrolysate (hydrolysed salmon meal: HSM). The basal diet containing 120 g/kg SM was incrementally replaced (0. 25, 50, 75, 100%) by HSM to produce five test diets used in two trials. A sixth diet was included which evaluated gelatin supplementation (trial 1) or pH neutralization (trial 2). In trial 1, each diet was produced using two processing conditions (laboratory extruded and formed with meat grinder) and offered to shrimp in a clear water system. The results demonstrate that up to 50% of the SM can be used to replace with HSM; however, further increases resulted in reduced performance of shrimp. The addition of gelatin reduced leaching but there was limited effect of processing on leaching. There were no detectible effects of pH adjustment of the diets. Results indicated that the growth performance of shrimp has not influenced by HSM up to 60 g/kg to replace 50% of the SM in practical diets; however, higher levels resulted in significant decrease in performance.     

Response of juvenile tench (Tinca tinca L.) fed practical diets with different protein contents and substitution levels of fish meal by soybean meal

A basal practical diet for juvenile tench (Tinca tinca) was formulated and elaborated to test several protein contents and substitution possibilities of fish meal (FM) by soybean meal (SBM) in a 90‐day trial with 5‐month‐old juveniles (30.54 mm TL, 0.30 g W). A factorial design included nine feeding treatments: three protein contents (50%, 40% or 30%) and three levels of replacement (0%, 25% or 45%) of FM protein by SBM protein. In addition, a commercial carp feed was used as reference. Final survival ranged from 98.2% to 99.4%. The 50% dietary protein with 0% or 25% replacement and 40% dietary protein with 25% replacement diets enabled higher growth (P < 0.05) and lower FCR (P < 0.05) than the rest of practical diets. Fish fed 50% dietary protein had similar growth than those fed carp feed (63.8% protein). Deformed fish averaged 1% for the practical diets and 87.6% for the carp feed. The basal practical diet has showed to be feasible and levels of 40–50% dietary protein with 25% replacement of FM protein by SBM protein can be recommended for juvenile tench aged 5–8 months.     

Growth performance of juvenile kuruma shrimp,Marsupenaeus japonicus (Bate) fed diets replacing fishmeal with soybean meal

A feeding trail was conducted to evaluate the effect of lowering dietary fishmeal (FM) levels while increasing levels of dehulled soybean meal (SBM) on growth, nutrient utilization and body composition of juvenile kuruma shrimp, Marsupenaeus japonicas. Five experimental diets were formulated to be isoenergetic, isolipidic and isonitrogenous with decreasing FM levels from 40 to 16% while increasing SBM from 0 to 33% respectively. Quadruplicate groups of shrimp (initial wt = 1.5 g) were fed the test diets for 56 days under the flow‐through system. There were no significant differences in final weight (g) and specific growth rate (SGR, % day) among shrimp fed FM40, FM34, FM28 and FM22 diets respectively. Growth parameters significantly decreased in shrimp when fed FM16 diet, which was the lowest level of FM. Feed intake was positively correlated with the SGR of shrimp, and the lowest one was found in shrimp fed FM16 diet. Protein gain and retention, whole body lipid, arginine and methionine significantly decreased in FM16 fed group. Thus, it is concluded that dietary FM could be reduced down to 22% with SBM without compromising growth, nutrient utilization and retention, and whole body composition of kuruma shrimp.     

Partial replacement of fishmeal by soybean meal in diets for juvenile cobia (Rachycentron canadum)

An 8‐week feeding experiment was conducted in floating cages (1.5 × 1.0 × 2.0 m) to determine the potential use of defatted soybean meal (roasted and solvent‐extracted) as a partial replacement of fishmeal in the isonitrogenous (approximately 450 g kg^?1 CP [crude protein]) diet for juvenile cobia with an initial average weight of about 8.3 g. Diets were formulated to include 0, 100, 200, 300, 400, 500 and 600 g kg^?1 (diets D0, D10, D20, D30, D40, D50 and D60, respectively) of fishmeal protein being substituted by defatted soybean meal without methionine supplementation. The results showed that weight gain rate decreased significantly when the replacement level of fishmeal protein was increased from 400 g kg^?1 to 500 g kg^?1, and the D60 diet was the lowest in all groups. These results indicate that up to 400 g kg^?1 of fishmeal protein can be replaced by defatted soybean meal without causing significant reduction in growth. Feed conversion ratio (FCR) and protein efficiency ratio (PER) were significantly affected by the replacement level of fishmeal protein being substituted by defatted soybean meal, when the replacement level of fishmeal protein was 200 g kg^?1 (diet, D20), FCR was the lowest and PER was the highest. There were no significant differences in the moisture, lipid, crude protein and ash content in whole body and muscle, while lipid content in liver increased as the dietary soybean meal replacement levels increased. There were significant differences in haemoglobin, haematocrit, red blood cell, plasma glucose and triglyceride concentration in fish fed diets with different soybean meal replacement levels. Results of this trial indicated that the optimum level of fishmeal protein replacement with defatted soybean meal, determined by quadratic regression analysis was 189.2 g kg^?1, on the basis of maximum weight gain.     

Meat yields in the introduced freshwater crayfish, Pacifastacus leniusculus (Dana) and Astacus leptodactylus Eschscholtz, from British waters

The freshwater crayfish industry in Britain is based on two species, Pacifastacus leniusculus (Dana) and Astacus leptodactylus Eschscholtz, which were introduced during the 1970s and 1980s. The former is widely cultivated but both are also established in the wild, from where they are harvested. Very few studies have been made of the meat yield in these two species and none on British populations. Two essentially wild populations were assessed for their meat yield. Due to its more massive claws male P. leniusculus had a higher meat yield than male and female A. leptodactylus and female P. leniusculus in both winter and summer months. Less difference was found between the yield of tail meat between the sexes and species. Compared with other studies, meat yield in the two British populations of P. leniusculus (11–15%) and A. leptodactylus (9–13%) would appear to be lower; possible reasons for this are discussed. However, expressing meat yield as a percentage of wet body weight, although useful for comparative purposes, can give conflicting results – examples of this are given. Meat yields from the claws of the two species indicated that positive allometric growth continued after sexual maturity.     

Effects of size grading on growth, survival and cheliped injuries of signal crayfish (Pacifastacus leniusculus Dana) summerlings (age 0+)

Effects of size grading and stocking density on growth and survival of 3.5‐month‐old signal crayfish (Pacifastacus leniusculus Dana) juveniles were investigated in a 3 × 2 factorial design with size group (small, large and mixed) and stocking density (25 and 200 individuals m^?2) as factors for 90 days. Carapace length and wet weight growth of the juveniles were affected by the presence or absence of other size groups, stocking density and animal size. All factors had statistically significant interactions, which make the interpretation of the results more complicated. The smaller crayfish grew faster in the absence of large animals and larger animals benefited from the presence of smaller cospecies. Increasing density decreased the growth in length and weight. Survival (82–100%) was good in all groups. Subsequently, the within population dynamics was studied by selectively removing the largest individuals (selectively removing (SR) group). Effects on growth and survival of the remaining juveniles were evaluated on 6‐month‐old P. leniusculus juveniles reared in plastic tanks (100 juveniles m^?2) for 122 days. Size distribution manipulation was performed at days 34 and 70. Juveniles in SR group grew significantly faster in comparison with a control group (RR), from which juveniles were removed randomly. Also, the survival rate was significantly higher in the SR group than in the RR group. In conclusion, size grading of juvenile P. leniusculus either at the start of the experiment or repeatedly during the experiment increased growth performance of smaller animals in length and weight.     

Partial replacement of fish meal with peanut meal in practical diets for the Pacific white shrimp,Litopenaeus vannamei

In this study, we replaced fish meal with peanut meal (PM) in isonitrogenous and isolipidic diets for Pacific white shrimp at inclusion levels of 0, 70, 140, 210, 280 and 350 g kg^?1. The diets were hand‐fed to three independent groups of shrimp three times a day over a 6‐week period. Shrimp fed PM diets at a level of 280 g kg^?1 or higher had lower per cent weight gain compared with those fed the basal diet, whereas shrimp fed PM diets at 140 g kg^?1 or higher had a lower feed utilization and protein efficiency ratio compared with shrimp fed the basal diet. The feeding rate in shrimp fed PM diets at 350 g kg^?1 and the survival and protease activity in shrimp fed PM diets at 210 g kg^?1 or higher were lower than that in shrimp fed the basal diet. Diets containing 280 g kg^?1 or higher of PM caused an increase in the whole‐body moisture content of the shrimp, but decreased whole‐body protein and ash contents compared with the basal diet. Nutrient digestibility was lower or tended to be lower in shrimp fed a PM diet compared with those fed the basal diet. The activities of peroxidase and acid and alkaline phosphatases in plasma decreased with increasing levels of PM inclusion up to 210 g kg^?1. Superoxide dismutase activity decreased at dietary PM levels of 280 g kg^?1 or higher. Aflatoxin B₁ residue in the muscle was not affected by any of the treatments and remained low. The data suggest that up to 140 g kg^?1 of PM could be included in practical diets for Pacific white shrimp.