Evaluation of a novel bacterial biomass as a substitution for soybean meal in plant‐based practical diets for Pacific white shrimp Litopenaeus vannamei

Three growth trials and a digestibility trial were designed to evaluate the efficacy of a novel bacterial biomass (BB) in commercial‐type feed formulation for Pacific white shrimp, Litopenaeus vannamei. In trial 1, the basal diet was supplemented with 0, 60 and 120 g/kg BB to replace soybean meal (SBM). Significant improvement was observed in the survival when BB was incorporated in the diets. However, shrimp fed diets containing 120 g/kg BB exhibited significantly lower weight gain (WG) and higher feed conversion ratio (FCR). To confirm the results from trial 1 and explore the effects of BB supplementation at low levels, the basal diet was incorporated with 0, 10, 20, 40, 60 and 120 g/kg BB to replace SBM in trial 2. Significant reductions in WG, FCR, lipid content of whole body, protein retention efficiency and most amino acids retention efficiency were detected in shrimp fed with diet containing 120 g/kg BB. Trial 3 was designed to elucidate whether the digestible protein is the cause of reduced growth. No improvements in terms of growth performance and FCR were detected in the treatments balanced for digestible protein. Apparent digestibility coefficients of energy, protein and amino acid (AA) for BB were determined using chromic oxide as an inert marker and the 70:30 replacement technique. The energy, protein and individual amino acid digestibility coefficients of BB were significantly lower than those of fish meal (FM) and SBM that were given at the same time. Results of this study indicated that BB can be utilized up to 40 g/kg in shrimp feed without causing a decrease in growth. However, supplementations (≥60 g/kg) of BB can result in negative effects on growth response, FCR and protein as well as amino acids retention efficiency. At the lower levels of inclusion, shrimp performance was improved when BB was supplemented on a digestibility basis; however, at the higher level of inclusion, there was no improvement, indicating there may be other nutrients limiting. Based on enhanced survival in the treatment with BB supplementation in trial 1, further research regarding the immune effects of BB in practical shrimp feed will be necessary.     

Bio‐Ag reutilization of distiller's dried grains with solubles (DDGS) as a substrate for black soldier fly larvae,Hermetia illucens,along with poultry by‐product meal and soybean meal,as total replacement of fish meal in diets for Nile tilapia,Oreochromis niloticus

A feeding trial was conducted in a closed system with Nile tilapia, Oreochromis niloticus, juveniles (mean initial weight, 2.66 g) to examine total replacement of menhaden fish meal (FM) with distiller's dried grains with solubles (DDGS), which had been used as substrate for the production of black soldier fly larvae, Hermetia illucens, in combination with soybean meal (SBM) and poultry by‐product meal (PBM), with or without supplementation of the amino acids (AA) DL‐methionine (Met), L‐lysine (Lys) and a commercial non‐amylaceous polysaccharide enzyme (Enz) product. Fish were fed seven isoenergetic [available energy (AE) = 4.0 kcal g^?1 of diet] and isonitrogenous (350 g kg^?1 protein as‐fed basis) practical diets formulated with equivalent digestible protein levels. Diet 1 was formulated to be similar to a commercial, high‐quality, tilapia diet containing 200 g kg^?1 FM. Diets 2–5 were formulated as a 2 × 2 factorial to replace FM with similar contributions from DDGS (45%), PBM (25%) and SBM (2.1–2.9%), but to differ in supplementation of AA and/or Enz preparation. Diets 6 and 7 were formulated to investigate the effects of a 2/3 and 1/3 reduction, respectively, in DDGS contribution to the replacement protein mix, with concomitant increases in SBM, with respect to diet 3, and were balanced with Lys and Met. After 6 weeks, growth responses were slightly attenuated (P ≤ 0.05) and average daily intake (ADI) and feed conversion ratio (FCR) were slightly higher in tilapia fed DDGS diets 2–5 compared to those of fish fed the FM control diet 1. Growth responses were not significantly affected by the presence or absence of AA or Enz (diets 2–5), or the level of DDGS (diets 3, 7 and 6). Whole‐body proximate composition was not different among treatments. Amino acid profiles of fish fed DDGS diets were not significantly different from those of fish fed the FM control. Evidence of interaction between AA and Enz supplementation was detected in whole‐body amino acid concentrations such that AA content was higher with AA or Enz addition alone, but lower when both were added to the diet. Results suggest that DDGS replacement of FM in tilapia diets can be substantial when diets are formulated on a digestible protein basis and DDGS is combined with highly digestible animal (PBM) and plant proteins (SBM).     

Supplementations of poultry by‐product meal and selenium yeast increase fish meal replacement by soybean meal in golden pompano (Trachinotus ovatus) diet

The effects of poultry by‐product meal (PBM) and selenium yeast (Se‐yeast) supplementations on fish meal replacement by soybean meal (SBM) in the diet of golden pompano (Trachinotus ovatus) were examined. In trial I, a 2 × 3 layout including two PBM levels (100 and 170 g kg^?1) and three levels of fish meal replacement (0, 40 or 60%) was used. At 100 g kg^?1 PBM, fish fed the basal diet exhibited the highest weight gain (WG) and nitrogen retention efficiency (NRE) and the lowest feed conversion ratio (FCR). At 170 g kg^?1 PBM, no significant differences were found in WG and NRE between fish fed the basal diet and diet with 40% of fish meal replaced by SBM. In trial II, the basal diet containing 170 g kg^?1 PBM (trial I) served as a reference. A 2 × 2 layout included two levels of fish meal replacement (40 or 60%) and two levels of Se‐yeast addition (0 and 1 g kg^?1). No significant differences were found in WG, feed intake, FCR and NRE between fish fed the reference diet and diet with 40 or 60% fish meal replacement plus 1 g kg^?1 Se‐yeast addition. This study indicates that supplementations of PBM and Se‐yeast can enhance the level of fish meal replacement by SBM in golden pompano diet. Dietary fish meal level can be reduced to 140 g kg^?1 by optimizing inclusion of SBM, PBM and Se‐yeast.     

Efficacy of crystalline methionine and microencapsulation methionine in diets for Pacific white shrimp Litopenaeus vannamei

An 8‐week growth trial was conducted to evaluate the efficacy of crystalline methionine (C‐Met) or microencapsulated methionine (M‐Met) in practical diets for Pacific white shrimp Litopenaeus vannamei. A high fishmeal reference diet was formulated with 15% fishmeal, and then, soybean meal (SBM) was used to replace 50% fishmeal as a low fishmeal basal diet (7.5% fishmeal). Graded levels (0.1%, 0.15% and 0.2%) of methionine originating from C‐Met or M‐Met were added to the basal diet. Each diet was randomly assigned to three tanks (40 shrimps per tank) in an indoor flow through seawater system. The results showed that the shrimp fed the basal diet with 0.15% or 0.20% methionine originating from 0.375% or 0.5% M‐Met had significantly higher final weight and weight gain as compared to shrimp fed the basal diet. The supplementation M‐Met in the basal diets resulted in increased serum ammonia in shrimp. Hepatopancreas amylase activity of shrimp showed a decreasing trend with increasing methionine supplementation, which is in contrast with the upswing trend in trypsin at pancreatic segment. This study indicated that the diets supplemented with 0.15% or 0.20% of methionine from M‐Met (0.58% or 0.65% of dietary methionine respectively) were effective in improving the nutritional value of SBM‐based diets deficient in methionine (0.48%) for the Pacific white shrimp.     

Replacement of Fish Meal with Soybean Meal,Alone or in Combination with Distiller's Dried Grains with Solubles in Practical Diets for Pacific White Shrimp,Litopenaeus vannamei,Grown in a Clear‐Water Culture System

The objective of this study was to evaluate inclusion of distiller's dried grains with solubles (DDGS) as partial replacement of commercial, solvent‐extracted soybean meal (SBM) in fish meal‐free diets for Pacific white shrimp, Litopenaeus vannamei. Aquaria connected to a recirculating biofiltration system were utilized to evaluate growth, survival, and feed conversion of shrimp during the 8‐wk feeding trial. Each 110‐L aquarium was stocked with 15 shrimp (mean individual weight 0.99 g) and fed one of five diets: a diet containing 20% fish meal (FM), which served as the control (Diet 1); a diet containing 0% FM and 52.5% SBM (Diet 2); and diets containing 0% FM and either 10, 20, or 30% DDGS as partial replacement of SBM (Diets 3, 4, and 5, respectively). Shrimp were fed according to a pre‐determined feeding chart five times daily (0730, 1030, 1330, 1630, and 1930 h) and there were three replicates per dietary treatment. The results from the feeding trial demonstrated that final weight, weight gain (g), and percentage weight gain were significantly higher (P < 0.05) for shrimp fed Diet 1 (10.96 g, 10.01 g, and 1051%, respectively) compared to shrimp fed diets containing DDGS; however, shrimp fed diets containing DDGS had similar (P > 0.05) final weight, weight gain (g), and percentage weight gain as shrimp fed a diet containing 0% FM and 52.5% SBM (Diet 2). Feed conversion ratio (FCR) of shrimp fed Diet 1 (2.84) was significantly lower (P < 0.05) compared to shrimp fed any other diet. Survival (%) was not different (P > 0.05) among treatments and averaged 77.3% for the study. This study demonstrated that practical shrimp diets containing no FM had an adverse impact on growth performance of white shrimp when grown in a clear‐water system and that further research is needed to refine diet formulations when culturing shrimp in these systems when attempting to feed a diet without FM.     

Comparison of L‐lysine·HCl and L‐lysine sulphate in the feed of Penaeus monodon and re‐evaluation of dietary lysine requirement for P. monodon

Two trials were conducted to compare L‐lysine HCl and L‐lysine sulphate regarding its availability to Penaeus monodon, and further evaluate the optimum dietary lysine requirement. In experiment 1, five experimental diets were formulated (D1, D2, D3, D4 and D5), a basal diet (D1), aimed at a low‐lysine concentration (2.22% dry matter), with lysine concentration of the other four diets increasing in two 0.25% L‐lysine intervals from either L‐lysine HCl (D2 and D3) or L‐lysine sulphate (D4 and D5). Each diet was fed at a restricted rate to three groups of 40 shrimp for 74 days. The highest values of growth performance (weight gain, WG; specific growth rate, SGR) and survival were observed with shrimp fed the L‐lysine HCl diet. Feed efficiency (FE) of shrimp fed D2 was significantly higher than that of shrimp fed D1 and D5 (P < 0.05), but without significant difference with shrimp fed D3 and D4 (P > 0.05). In experiment 2, six diets (d1, d2, d3, d4, d5 and d6) were formulated with six graded levels of lysine (2.21%, 2.41%, 2.59%, 2.87%, 3.11% and 3.29% of diet). Each diet was randomly assigned to triplicate groups of 40 shrimp for 74 days. WG, SGR and survival increased increasing levels of lysine up to 2.41% of diet and reached an apparent plateau. Broken‐line model analysis on WG and SGR indicated that the optimum dietary lysine level for optimal growth of shrimp was 2.37% of diet, corresponding to 5.78% of dietary protein. In conclusion, results of this trial suggest that L‐lysine HCl is superior to L‐lysine sulphate when fed to Penaeus monodon and optimal growth can be obtained at lysine levels corresponding to 2.37% of diet, or 5.78% of dietary protein in this specie.     

Evaluation of soybean meal from different sources as an ingredient in practical diets for Pacific white shrimp Litopenaeus vannamei

Solvent extracted soybean meal (SBM) is generated using different varieties of soybeans grown under a range of conditions and then processed at different crushing plants. Due to its competitive cost and availability, it is a popular plant‐based protein source for shrimp feed formulations. However, there is limited information about effects of variations in the nutritional composition of soybean meal have on performances of shrimp. Hence, the present study was designed to determine the effects of different soybean sources on the growth performances of Litopenaeus vannamei. Two growth trials were conducted with iso‐nitrogenous and iso‐lipidic (350 g/kg protein and 80 g/kg lipid) test diets formulated with 25 sources of soybean meal. Trial one incorporated 14 treatments including a soy‐based diet containing 517 g/kg SBM (eight replicates) and this soy source was then replaced with 13 different soybean sources (four replicates per treatment). The second trial used the same basal diet and 11 different sources of soybean meal (Total 12 diets) with five replicates per treatment. Both growth trials were conducted with a stocking density of 10 shrimps/aquarium in a semi‐closed recirculating system and the initial weight of shrimps for trials 1 and 2 were 0.23 g ± 0.02 and 0.67 g ± 0.02 respectively. During the two trials, shrimp were fed four times/day assuming a FCR of 1.8, over 42 days for trial 1 and 35 days for trial 2. Results indicated that there are differences among sources of soybean meal for standardized percentage TGC. Diet 21 that contained SBM4550 had the largest value for TGC whereas the lowest value for TGC was observed for shrimp fed diet 17 that contained SBM45536. According to the statistical analysis that was used to interpret the growth performance data from the complete chemical profile of the SBM, phosphorous, phytate‐phosphorous and total phytic acid levels had positive correlations (p < 0.005) with TGC whereas raffinose (p = 0.086) had a negative correlation with TGC. Results of this work indicates phosphorous, phosphorous in phytic acid and total phytic acid and raffinose are important components in SBM that may have significant effects on the growth performances of pacific white shrimp.     

The evaluation of practical diets on a basis of digestible crude protein,lysine and methionine for Litopenaeus vannamei

A feeding trial was conducted to evaluate the efficacy of replacing fish meal (FM) with blood meal (BM), poultry by‐product meal (PBM), meat and bone meal (MBM) and shrimp head meal (SHM), rapeseed meal (RM) and peanut meal (PM) on a digestible basis of crude protein and lysine and methionine in five practical diets for the Pacific white shrimp at the FM levels of 300, 250, 200, 150 and 100 g kg^?1 under laboratory conditions. Each of the five experimental diets was hand‐fed to four replicate tanks of shrimp with an average weight of 0.33 ± 0.03 g to satiation at each meal. The shrimp were fed three times a day over a six‐week period. The per cent weight gain of initial body weight (WG%) was significantly lower in shrimp fed 100 g kg^?1 FM diet, but the value for hepatosomatic index (HSI) and the level of blood urea nitrogen (BUN) tended to be higher in shrimp fed 100 g kg^?1 FM diet than those in shrimp fed other diets. The lowest value for feeding rate (FR) occurred for shrimp fed the basal diet and was significantly lower than that in shrimp fed the FM diets at 100–150 g kg^?1. Shrimp fed diets containing 200 g kg^?1 or lower FM had significantly lower feed utilization than those fed the 250 g kg^?1 FM diet and the basal diet. The protein efficiency ratio (PER) in the shrimp fed the basal diet was significantly higher than in the other FM diets. Decreasing the FM replacement level significantly reduced nutrient digestibility except in the cases of ash and gross energy, but it did not affect the survival, condition factor (CF), body composition, digestive enzyme activity or plasma transaminase activity. The results of the study indicate that feeding a diet formulated on a digestible basis and involving FM replacement with other protein sources at a greater replacement proportion will not produce a level of shrimp growth equal to that achieved by feeding the basal diet.     

Protein‐sparing effect of carbohydrate in the diet of white shrimp Litopenaeus vannamei at low salinity

Juvenile Litopenaeus vannamei were fed for 8 weeks with diets containing four ratios of protein to carbohydrate (CBH) at P26 : C30, P30 : C25, P34 : C19 and P38 : C14, respectively, at 3.0 g L^?1 salinity. Shrimp weight gain of P34 : C19 group was the highest and differed from the shrimp fed the P26 : C30 or P30 : C25 diet. Shrimp fed the P26 : C30 diet obtained higher survival than those fed other diets. Shrimp fed the P34 : C19 diet contained the highest body protein and lipid, which were significantly higher than those fed the P38 : C14 diet. Shrimp fed the P30 : C25 diet had the highest haemolymph glucose content, which was significantly higher than those fed the P26 : C30 or P38 : C14 diet. Shrimp muscle glycogen of the P26 : C30 group was the highest. Hepatopancreas B‐cell number of shrimp fed the P26 : C30 diet was lower than those fed other diets, and the R cell number was the highest in the shrimp fed the P30 : C25 diet. This study indicates that the protein‐sparing effect by CBH occurred in the P30 : C25 and P34 : C19 groups because these proteins to CBH ratios can support normal growth. Within the range of basic energy demand, the high dietary CBH to protein ratio can improve L. vannamei survival at low salinity.     

Immunostimulatory effect of mangrove‐derived marine yeasts in Penaeus monodon

This study attempted to assess the efficacy of mangrove‐derived marine yeasts as a source of immuno‐stimulant in the tiger shrimp, Penaeus monodon. The shrimp was fed on the diets in supplementation with yeast biomass at 10% for a period of 15 days and then challenged with the pathogenic Vibrio cholerae. The animals were assessed for immune responses in terms of total haemocyte counts, phenol oxidase and endobiotics. Among the yeasts tested, Rhodotorula minuta was found to have high immunostimulatory effect in the shrimps especially after challenge with the pathogenic vibrio.     

Evaluation of flash dried yeast as a nutritional supplement in plant‐based practical diets for Pacific white shrimp Litopenaeus vannamei

Growth and digestibility trials were conducted to evaluate the use of flash dried yeast (FDY) as a supplement in practical shrimp feeds. The six‐week growth trial evaluated the effects of FDY supplementation (0, 10, 20, 40 and 60 g kg^–1) in the plant‐based practical diet on the performances and proximate compositions of juvenile Pacific white shrimp, Litopenaeus vannamei. Final biomass, final mean weight, per cent weight gain (WG), feed conversion (FCR) and protein retention efficiency (PRE) of Pacific white shrimp were not significantly influenced when FDY was added up to 40 g kg^–1 of the diet. However, 60 g kg^–1 FDY supplementation significantly reduced growth, feed utilization and protein retention. Supplementation of FDY in the practical diets of Pacific white shrimp did not affect protein, moisture, lipid, crude fibre, and ash content of whole shrimp body. Apparent digestibility coefficients of energy, protein, and amino acid (AA) for FDY were determined using chromic oxide as an inert marker and the 70:30 replacement technique. The energy and protein digestibility of FDY were 38.20% and 53.47%, respectively, which were significantly lower than fishmeal (FM) and soybean meal (SBM) that were run at the same time. Most amino acid digestibility of FDY was lowest among the three ingredients tested. Results of this work indicated that energy, protein and amino acid digestibility of FDY are lower compared to SBM and FM, and high levels supplementation (≥60 g kg^–1) of FDY can cause negative effects to the growth response of Pacific white shrimp. Based on these results, further research regarding the effects of the low level inclusion of FDY in practical diets on immune responses of Pacific white shrimp is warranted.     

Growth performance,haematological parameters,antioxidant status and salinity stress tolerance of juvenile Pacific white shrimp (Litopenaeus vannamei) fed different levels of dietary myo‐inositol

A 10‐week growth trial was run to evaluate effects of myo‐inositol (MI) on growth performance, haematological parameters, antioxidative capacity and salinity stress tolerance of Litopenaeus vannamei. Six practical diets supplemented with graded levels of MI (designated as MI0, MI600, MI1200, MI2400, MI 3600 and MI4800 for 448.8, 974.2, 1568.0, 2810.6, 3835.5 and 4893.6 mg/kg diet, respectively) were fed to six replicate groups of L. vannamei (mean initial body weight 0.63 ± 0.00 g). The results showed that significant increment of growth performance was observed in shrimp fed MI600 diet than those fed MI1200 diet. Lipid concentration in whole body of the shrimp fed MI600 diet was significantly increased. Shrimp fed MI0 diet had lower total protein (TP) as compared to shrimp fed the MI‐supplemented diets (except MI4800 diet). In general, lower activities of antioxidant enzymes and higher malondialdehyde (MDA) content in haemolymph and hepatopancreas were recorded in shrimp fed MI0 diet, compared to those fed the MI‐supplemented diets. Reduced survival after 7‐h salinity stress was present in shrimp fed MI0 diet as compared to those fed MI4800 diet. Dietary MI requirement for glutathione peroxidase activity of L. vannamei was 2705 mg/kg diet.     

Effects of various dietary levels of copper hydroxychloride on growth performance and tissue response in Pacific white shrimp Litopenaeus vannamei fed practical diets

Two trials were conducted to evaluate the performance of Pacific white shrimp Litopenaeus vannamei offered diets containing various copper (Cu) levels from Cu hydroxychloride (Cu₂(OH)₃Cl) containing 58.81% copper in the clear water recirculating system. In both trials, the basal diet (360 g kg^?1 protein, 80 g kg^?1 lipid) containing approximately 10 mg Cu kg^?1 was primarily comprised of fishmeal, soybean meal, corn protein concentrate and whole wheat. In trial 1, test diets were produced supplementing the basal diet with 5, 10, 20, 40 and 60 mg Cu kg^?1 from Cu hydroxychloride. Four replicate groups of 15 shrimp per tank (initial weight 0.28 g) were offered diets in slight excess over 8 weeks. In trial 2, the basal diet was supplemented with 30, 90, 150, 210 and 270 mg Cu kg^?1 from Cu hydroxychloride. Seven replicate groups of 15 shrimp per tank (initial weight 0.22 g) were offered feed in slight excess over 7 weeks. At the end of the two growth trials, no significant differences were observed in final biomass, final mean weight, percentage weight gain, feed conversion ratio (FCR) and survival. In trial 1, the Cu concentrations of the carapace, hepatopancreas and whole shrimp linearly increased with increasing dietary Cu supplements. In trial 2, polynomial regression of Cu concentrations of the carapace, hepatopancreas and whole shrimp against analysed dietary Cu content indicated that a plateau was reached at 215 mg analysed Cu kg^?1. Results of this study indicate that there was no negative effect of high levels of Cu supplement with regard to growth and survival. Tissue levels generally increased up to around 200 mg Cu kg^?1 diet and then decreased, possibly indicating a shift in physiology.     

Suitable dietary chitosan improves the growth performance,survival and immune function of tiger shrimp,Penaeus monodon

Different levels of dietary chitosan on growth performance, survival and stress tolerance to air exposure was studied in tiger shrimp, Penaeus monodon. Shrimp (mean initial wet weight about 1.16 g) were fed with six different diets (C0, C0.05, C0.1, C0.2, C0.3 and C0.4) containing six level of chitosan (0%, 0.05%, 0.1%, 0.2%, 0.3% and 0.4% respectively) in triplicate for 60 days. Growth performance [final body wet weight (FBW); weight gain (WG); biomass gain (BG)] of shrimp fed chitosan‐containing diets were higher (P < 0.05) than that of shrimp fed the basal diet, shrimp fed C0.1 diet showed the highest value of growth performance. Survival of shrimp in C0.1 and C0.2 diet groups were higher (P < 0.05) than that of shrimp in C0, C0.05 and C0.4 diet groups but without statistical difference (P > 0.05) in shrimp fed C0.3 diet group. Whole body and muscle lipid contents decreased with increasing dietary chitosan levels. Plasma total cholesterol and triglyceride contents of shrimp fed C0 diet was significantly higher (P < 0.05) than that of shrimp fed chitosan‐containing diets. Plasma alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities of shrimp fed C0 diet were higher than those of shrimp fed chitosan‐containing diets. Digestive gland malondialdehyde (MDA) and carbonyl protein contents of shrimp fed chitosan‐containing diets were lower (P < 0.05) than that of shrimp fed C0 diet. Total haemocyte count of shrimp fed C0 diet was lower (P < 0.05) than that of shrimp fed chitosan‐containing diets. On the contrary, the haemolymph clotting time of shrimp fed C0 diet was higher (P < 0.05) than that of shrimp fed chitosan‐containing diets. In conclusion, all results suggested that dietary intake containing 0.1% and 0.2% chitosan enhanced the growth of shrimp, whereas a higher level than 0.3% and 0.4% decreased growth of shrimp. Second‐degree polynomial regression analysis of WG and BG indicated that the optimum supplement of dietary chitosan level should be 0.19–0.21%.     

Use of plant‐based protein concentrates as replacement for fishmeal in practical diets for the Pacific white shrimp (Litopenaeus vannamei) reared under high stocking density and low salinity conditions

Two feeding trials were conducted to investigate the effect of replacing fishmeal with a combination of soy and corn protein concentrate (1:1 ratio) on growth performance of the Pacific white shrimp (Litopenaeus vannamei). A basal diet containing 200 g/kg fishmeal was systematically reduced (200, 150, 100, 50 and 0 g/kg) with protein concentrate on an isonitrogenous basis. Additionally, two diets containing 0 or 50 g/kg fishmeal were supplemented with lysine and methionine to evaluate possible limitations in EAAs. Each diet was randomly fed to five replicate tanks (15 shrimp per 75 L aquaria) reared in an indoor clear water system (Trial 1), or four replicate circular tanks (100 shrimp per 800 L) reared in outdoor green water system (Trial 2). In trial 1, results indicated a slight decrease in shrimp performance as fishmeal was replaced at the highest levels. Meanwhile, the supplementation of lysine and methionine to the diets did not result in shifts in survival, growth or FCR. In trial 2, there were no significant differences in growth performance across the tested diets. This study demonstrated that plant‐based protein concentrates can be used to replace fishmeal in practical shrimp diet in clear and green water under high stocking density.     

Effects of replacing fish meal with soybean meal and peanut meal on growth,feed utilization and haemolymph indexes for juvenile white shrimp Litopenaeus vannamei,Boone

An 8‐week feeding trial was conducted to evaluate the effects of replacing fish meal (FM) with soybean meal (SBM) and peanut meal (PM) on growth, feed utilization, body composition and haemolymph indexes of juvenile white shrimp Litopenaeus vannamei, Boone. Five diets were formulated: a control diet (FM30) containing 30% fish meal and four other diets (FM20, FM15, FM10 and FM5) in which protein from fish meal was substituted by protein from SBM and PM. The dietary amino acids of diets FM20, FM15, FM10 and FM5 were equal to those of the diet FM30 by adding crystalline amino acids (lysine and methionine). Each diet was randomly assigned to triplicate groups of 30 shrimps (initial weight = 0.48 g), each three times daily. The results indicated that shrimp fed the diets FM15, FM10 and FM5 had poor growth performance and feed utilization compared with shrimp fed the control diet. No difference was observed in feed intake, survival and body composition among dietary treatments. The plasma total cholesterol level of shrimp and the digestibility of dry matter, protein and energy contained in the diets decreased significantly with increasing PM and SBM inclusion levels. Results of this study suggested that fish meal can be reduced from 300 to 200 g kg^?1 when replaced by a mixture of SBM and PM.     

Effects of diets supplemented with either individual or combined probiotics,Bacillus subtilis E20 and Lactobacillus plantarum 7‐40, on the immune response and disease resistance of the mud crab,Scylla paramamosain (Estampador)

Two trials, including firstly, diets incorporating individual or combined species of probiotics, Bacillus subtilis E20 and Lactobacillus plantarum 7‐40, were fed to the mud crab, Scylla paramamosian, for 28 days to evaluate the growth, immunity and disease resistance, and secondly, the optimal level of B. subtilis E20 in the diet by tracking the growth, immunity and disease resistance after 28 days of feeding were analysed. No significant differences in growth, total haemocyte counts, respiratory bursts, superoxide dismutase, or glutathione peroxidase were found in the two trials. Crabs fed the B. subtilis E20‐containing diet (D20) had significantly increased phenoloxidase (PO) activity, phagocytic activity (PA) and disease resistance compared with crabs fed the control and the mixed probiotics diet (MD). The mortality of crabs fed the D20 was significantly lower than that of crabs fed the L. plantarum 7‐40‐containing diet. L. plantarum 7‐40 had a great inhibitory effect on the growth of B. subtilis E20, which may have led to the decreased probiotic effect of the MD. An analysis of the optimal level of B. subtilis E20 in the diet showed that crabs fed the B. subtilis E20‐containing diet at a level of 10^9–10 cfu kg^?1 had better immune response of PO and PA, and disease resistance in the second trial.     

Use of high‐protein brewer’s yeast products in practical diets for the Pacific white shrimp Litopenaeus vannamei

Two 6‐week growth trials and a digestibility trial were conducted to evaluate the effects of brewer's yeast in practical shrimp feeds. In the first growth trial, graded levels (0, 60, 120, 180 and 240 g/kg) of a brewer's yeast (BY50) were used to replace fishmeal and soybean meal, referred to as Diet DBY0, DBY6, DBY12, DBY18, DBY24 and Diet LFM0, LFM6, LFM12, DBY18 and LFM24, respectively. The results showed that there were no significant differences in final biomass, survival, protein retention efficiency and feed conversion ratio; however, limited differences in final weight and weight gain were shown in the FM replacement series. There was no significant difference on the growth performance in the SBM replacement series. The second growth trial was conducted with Diet DBY0, DBY12, DBY18, DBY24, LFM0 and a low‐FM diet containing 20 g/kg of BY with 700g/kg (?) protein (Diet DBY70). Shrimp fed with Diet DBY0 exhibited significantly higher final mean weight and weight gain than those offered the Diet DBY24. Nutrient availability of BY50 and BY70 was similar to SBM and significantly higher than FM. Results indicated that 180–240 g/kg BY50 can be effectively used in shrimp diets as a replacement for FM, or up to 240 g/kg when replacing SBM.     

Effects of dietary nucleotides on growth,survival and metabolic response in whiteleg shrimp,Litopenaeus vannamei against ammonia stress condition

This trial was conducted to evaluate the effects of nucleotides on growth of whiteleg shrimp, Litopenaeus vannamei, and the survival and metabolic responses to ammonia stress test. Experimental diets were as follows: low fish meal diet (LFMD), and four LFMD test diets, each supplemented with 0.1% guanosine monophosphate (GMP), 0.1% inosine monophosphate (IMP), 0.1% mixture of GMP and IMP and 0.1% mixture of GMP, IMP, uridine monophosphate (UMP) and cytidine monophosphate (CMP). The shrimp specimens (initial body weight: 0.99 ± 0.01 g) were randomly allocated into five groups and fed four times daily for 8‐weeks. After the trial, final body weight was recorded and haemolymph was withdrawn for haematological analysis. The shrimp was then challenged with 70 mg/L ammonia (LC50) for 10 days. Survival and haemolymph of the shrimp were taken after exposure to ammonia. The highest growth performance was observed in the shrimp fed diet supplemented with GMP (p < .05), while survival was not influenced by the test diets in the feeding trial. In the ammonia challenge test, the highest survival was observed in the shrimp fed GMP supplemented diet compared to others. The plasma protein, glucose and cholesterol levels increased in all the treatments while triglycerides level decreased post challenge. Cortisol level recovered at day 10th after the challenge. Shrimps fed with nucleotides diets showed higher protein and glucose level compared to control groups post challenge. In general, nucleotides supplemented in the diet enhanced growth, improved stress resistance while modulating the haemolymph metabolites in L. vannamei under ammonia stress.     

Evaluation of some haemolymph biochemical properties and F‐cell prevalence in hepatopancreas of white leg shrimp (Litopenaeus vanammei) after fed diets containing apple cider vinegar and propionic acid

The present study aimed to evaluate the effect of dietary ACV (apple cider vinegar) and PA (propionic acid) supplementation on some biochemical properties of haemolymph and fibrillar cell (F‐cell) number in the hepatopancreas of shrimp. Five different diets supplemented with 0%, 1%, 2%, 4% ACV and 0.5% PA diets were fed to Litopenaeus vanammei. Some biochemical parameters of haemolymph (cortisol, alkaline phosphatase, albumin, urea, uric acid, creatinine, phosphorus, total hemocyte count) and prevalence of F‐cell in hepatopancreas were examined after 60 days feeding trial. The albumin concentration and total hemocyte count in 2% and 4% ACV and PA groups were significantly higher than those of other groups (p < .05). Moreover, the highest phosphorus concentration was detected in shrimp fed 4% ACV and PA experimental diets (p < .05). No significant differences in haemolymph cortisol, urea, uric acid, creatinine, alkaline phosphatase and tubule area were observed among the experimental groups (p > .05). 2% ACV group showed more F‐cell number in hepatopancreas than other groups while the reduction in F‐cell number was observed in the PA group. Based on these observations, the tested ACV and PA diets remarkably exhibited positive impacts on nutritional value and they may be a potential for adding to shrimp diet.