In vitro and in vivo selection of probiotic purple nonsulphur bacteria with an ability to inhibit shrimp pathogens: acute hepatopancreatic necrosis disease‐causing Vibrio parahaemolyticus and other vibrios

Shrimp cultivation has been faced with huge losses in productivity caused by infectious shrimp pathogenic vibrios, especially Vibrio parahaemolyticus that causes acute hepatopancreatic necrosis disease (AHPND). Hence, purple nonsulphur bacteria (PNSB) were isolated from shrimp ponds for investigating their abilities to control shrimp pathogenic Vibrio spp. and their use as probiotics for sustainable shrimp cultivation. Based on their probiotic properties, strains S3W10 and SS15 were selected because of their strong abilities to produce amylase, gelatinase and vitamin B12. However, only three PNSB strains (SS15, TKW17 and STW181) strongly inhibited V. harveyi_KSAAHRC and V. vulnificus_KSAAHRC including V. parahaemolyticusAHPND strains by secreting antivibrio compounds. Four selected PNSB also grew in the presence of pancreatic enzymes, and they were identified as Rhodobacter sphaeroides for strains S3W10, SS15 and TKW17 and Afifella marina for strain STW181. The effects of a mixed culture were also investigated as follows: T1 (S3W10 + SS15), T2 (S3W10 + TKW17) and T3 (S3W10 + STW181) on postlarval white shrimp (Litopenaeus vannamei) for 60 days by comparison with a control. All three probiotic PNSB sets significantly improved the digestive enzyme activities and shrimp growth with their proliferation in shrimp gastrointestinal tract although the shrimp survival was not significantly different. They also significantly reduced the cumulative mortality of shrimp exposed to a virulent AHPND strain (V. parahaemolyticusSR2). This is the first to conclude that selected probiotic PNSB strains have great potential to be used for shrimp cultivation to control vibrios including AHPND strains.     

Anti‐PirA‐like toxin immunoglobulin (IgY) in feeds passively immunizes shrimp against acute hepatopancreatic necrosis disease

Acute hepatopancreatic necrosis disease (AHPND), caused by a toxin‐producing Vibrio parahaemolyticus strain, has become a serious threat to shrimp aquaculture. The need to regulate antibiotic use prompted the development of alternative ways to treat infections in aquaculture including the use of chicken egg yolk immunoglobulin (IgY) for passive immunization. This study evaluated the protective effect of IgY against AHPND infection in Litopenaeus vannamei (Boone). IgY was isolated from eggs laid by hens immunized with recombinant PirA‐like (rPirA) and PirB‐like (rPirB) toxins. Whole‐egg powders having IgY specific to rPirA (anti‐PirA‐IgY) and rPirB (anti‐PirB‐IgY) and IgY from non‐immunized hen (control‐IgY) were mixed with basal diets at 20% concentrations and used to prefeed shrimp 3 days before the bacterial challenge test. Survival rates of the challenged shrimp fed the anti‐PirA‐IgY, anti‐PirB‐IgY and control‐IgY diets were 86%, 14% and 0%, respectively. Only the feed containing anti‐PirA‐IgY protected shrimp against AHPND. Increasing the concentration of rPirA antigen to immunize hens and lowering the amount of egg powder in feeds to 10% consistently showed higher survival rates in shrimp fed with anti‐PirA‐IgY (87%) compared with the control (12%). These results confirm that addition of anti‐PirA‐IgY in feeds could be an effective prophylactic method against AHPND infection in shrimp.     

Dietary supplementation of probiotics and influence on feed efficiency,growth parameters and reproductive performance in female rainbow trout (Oncorhynchus mykiss) broodstock

The aim of this study was to determine the effects of dietary probiotics on reproductive performance, growth, haematological and biochemical parameters of female rainbow trout broodstock. A total of 60 broodstocks with an average initial weight of 2,267.4 ± 54.9 g were divided into four groups and three replicates in raceway ponds. Fish were fed with diets containing 0 (control), 1 × 10⁹ (P1), 2 × 10⁹ (P2) and 4 × 10⁹ (P3) CFU probiotic per kg diet twice a day for 8 weeks before spawning season. Results revealed that higher levels of dietary probiotics (P3) enhanced protein efficiency ratio and decreased feed conversion ratio (p < .05). There were no significant differences in haematological and other growth parameters among different treatments. According to the results, probiotic‐fed treatments had the lowest levels of cholesterol (237.7 ± 4.3 mg/dl) and the highest levels of total protein (11.3 ± 0.3 g/dl) and albumin (6.9 ± 0.3 g/dl), so that differences were found between P3 and control groups in all cases (p < .05). Based on the observations from reproductive parameters, the highest egg diameter, working and relative fecundities, fertilization and hatching rates, eyed eggs survival and alevins survival rates up to the absorption of the yolk sac were observed in P3 treatment (p < .05). Moreover, eyeing, hatching and yolk sac absorbing stages in P3 treatment were earlier than those in other treatments (p < .05). The results of present study demonstrated that probiotic supplementation improved reproductive performance and some growth and biochemical parameters in female rainbow trout broodstock and the best performance was observed in fish fed 4 × 10⁹ CFU probiotic per kg diet. Due to an increase in egg production and egg size in probiotic‐fed treatments, this feed additive can be used as a suitable ingredient to increase high‐quality egg production in rainbow trout breeders.     

The effects of water additive Bacillus cereus and Pediococcus acidilactici on water quality,growth performances,economic benefits,immunohematology and bacterial flora of whiteleg shrimp (Penaeus vannamei Boone, 1931) reared in earthen ponds

This study was aimed to investigate the effects of two probiotics, Bacillus cereus and Pediococcus acidilactici, on the water quality, growth performance, the survival ratio, economic benefits, immunohematology and bacterial flora in the intestine of whiteleg shrimp, Litopenaeus vannamei after 110 days. Nine earthen ponds (each one 1.2 hectare) were adjusted as three treatments including control (without adding bacteria), containing P. acidilactici probiotic (10⁶ CFU/mL) and containing B. cereus probiotic (10⁶ CFU/mL). The results showed that the adding B. cereus and P. acidilactici to the water pond positively decreased nitrate, ammonia and biochemical oxygen demand when compared with the control group (p < .05). Regarding growth performance, treating shrimp with B. cereus caused significantly higher weight gain (16.72 g) and survival ratio (94.50%) in comparison with control group (p < .05). Using these probiotics could increase shrimp production (27.30%, 18.42%) and net income (92.94%, 49.20%) as well. Respect to immunity, total hemocyte count (9.00), total protein (8.92 g/dl) and lysozyme activity (21.55 U/ml) in treated whiteleg shrimp with B. cereus were significantly higher than those untreated (p < .05). In conclusion, adding B. cereus (10⁶ CFU/ml) to the earthen pond can be suggested in shrimp farm.     

Enhancement of growth performance, digestive enzyme activities and disease resistance in black tiger shrimp (Penaeus monodon) postlarvae by potential probiotics

Outbreaks of multidrug-resistant pathogens have been constraint on aquaculture production in Thailand, thereby controlling shrimp pathogens by preventive probiotics being importance to sustain the aquaculture system. In this study, the effect of potential probiotics, Bacillus subtilis and Enterococcus sp. was related to growth, digestive enzyme activities (trypsin and chymotrypsin) and pathogenic resistance by postlarval black tiger shrimp (Penaeus monodon). The experiment was divided into two treatments, in triplicate, with and without supplementation of probiotics as a food additive. Shrimp fed with probiotics for a culture period of 84 days showed a significant increase (P < 0.05) in weight (2.03 ± 0.29 g) and survival (71.91 ± 3.15 %) in comparison with non-treated shrimp (1.53 ± 0.28 g and 65.20 ± 5.68 %, respectively). Trypsin activity of treated shrimp was significantly higher (P < 0.05) than that of control shrimp whereas chymotrypsin activities of the two treatments were not significantly different (P > 0.05). After challenging P. monodon postlarvae with a shrimp pathogen, Vibrio harveyi for 10 days, percentage of mortality of P. monodon postlarvae fed with probiotics was 46.67 ± 1.44 %, significantly lower (P < 0.05) than that of non-treated shrimp (61.67 ± 6.29 %). This study showed that potential probiotics was appropriate for application in P. monodon postlarvae cultivation under laboratory condition due to improvement of shrimp weight and survival, enhancement of trypsin activity and reduced mortality causing by pathogenic V. harveyi. This is the first publication reported the effect of probiotics on trypsin and chymotrypsin activities of P. monodon postlarvae.     

Partial and total replacement of fish meal by marine microalga Spirulina platensis in the diet of Pacific white shrimp Litopenaeus vannamei: Growth,digestive enzyme activities,fatty acid composition and responses to ammonia and hypoxia stress

In the this study, we evaluated the effect of replacement of fish meal by a marine microalgae Spirulina platensis on growth, digestive enzyme activities, fatty acid composition and responses to ammonia and hypoxia stress in Pacific white shrimp Litopenaeus vannamei (2.6 ± 0.2 g). Experimental diets contained S. platensis at 0%, 25%, 50%, 75% and 100% replacement levels. After 8 weeks of feeding trial, growth parameters and proximate body composition were not significantly different among treatments (p > .05). Amylase and lipase activities did not show any significant differences between control group and other experimental diets (p > .05), while activities of trypsin and chymotrypsin were significantly higher in shrimp fed diet with 50% substitution of microalgae compared to control group. Fatty acid contents, particularly polyunsaturated fatty acids (PUFAs) including arachidonic acid (ARA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), were significantly higher in control diet compared to other experimental diets. On the contrary, the majority of fatty acids including the contents of PUFAs in the whole body of L. vannamei fed with different levels of S. platensis were significantly higher compared to those of control group. After 48‐h exposure to ammonia, survival per cent was not statistically different between all groups (p > .05), but in hypoxia challenge, the survival per cent of control group was significantly less than that of treatments fed diets contained S. platensis (p < .05). Altogether, o ur results demonstrated the effectiveness of S. platensis as a reliable protein source for substitution of fish meal in shrimp aquaculture.     

Does Biofloc Improve the Energy Distribution and Final Muscle Quality of Shrimp,Litopenaeus vannamei (Boone, 1883)?

In a 45‐d experiment, Litopenaeus vannamei was cultured in two treatments, biofloc technology or clear water recirculating aquaculture system, to evaluate the effect on growth and survival, energy balance, and texture of the marketable product. The experimental design consisted of 40 plastic tanks of 54 L (20 tanks per treatment), with a density of 140 organisms/m³ in each culture system. The final body weight, daily growth coefficient, and survival were significantly higher (P < 0.05) in biofloc technology (12.40 g, 5.0%g/d, and 87.1%, respectively) than in the clear water system (7.0 g, 1.4%g/d, and 74.2%). The retained energy and energy content of exuviae were significantly higher for shrimp in the biofloc technology (448.5 ± 36.4 and 22.4 ± 1.8 J/shrimp/d, respectively) than in clear water (246.3 ± 40.9 and 12.3 ± 2.0 J/shrimp/d, respectively). Routine metabolism was significantly higher for the clear water treatment (411.4 ± 123.8 J/shrimp/d). Shear force was higher in the biofloc technology, indicating greater muscle firmness; this matched the gel electrophoresis patterns of the proteins extracted from the muscle tissues. This suggests that biofloc technology could be used not only to improve growth and survival in L. vannamei but also to enhance the final product quality and acceptability in the market.     

Polyclonal antibody‐based farmer‐friendly flow‐through test for the detection of acute hepatopancreatic necrosis disease in shrimp

Early mortality syndrome (EMS) or acute hepatopancreatic necrosis disease (AHPND) is currently the most significant disease of shrimp in farms of Vietnam, Thailand, Malaysia, China and Mexico, and there is a great risk that it may spread to other shrimp farming countries. Although, an array of sophisticated detection tools for AHPND available, there is a need for a sensitive, simple and rapid detection method. In this study, a simple, sensitive, rapid and polyclonal antibody‐based farmer‐friendly flow‐through assay (FTA) test has been developed for the detection of AHPND pathogen. The recombinant Photorhabdus insect‐related (Pir) A toxin‐like protein of AHPND pathogen was used to immunize rabbits at 21‐day interval observed for highest antibody titre after third booster by ELISA. The raised rabbit antiserum was purified by affinity chromatography and characterized by Western blot. The antiserum showed no cross‐reactivity with AHPND‐free Vibrio parahaemolyticus, V. anguillarum, White Spot Virus (WSV), Aeromonashydrophila and Aphanomycesinvadans. This polyclonal rabbit antiserum was used to develop a farmer‐friendly FTA test for the detection of AHPND pathogen. This simple FTA testis is more sensitive and could detect PirA^VP toxin up to 0.121 µg/ml, compared with 0.242 µg/ml by immunodot assay. Furthermore, FTA test requires only 8–10 min for completion, compared with 3 hr by immunodot thus found to be more sensitive, specific and cost‐effective. Collectively, sensitive FTA test would help shrimp farmers to take real‐time management decisions, especially emergency harvest and finally be a better hope for the prevention of AHPND.     

Integrated rearing system approach in the farming of mud crab,shrimp, fish,oyster and periphyton in bracksihwater pond

Diversification of production systems has been identified as one of the major strategies for the long‐term sustainability of brackishwater aquaculture. On the context of diversification, a 180‐day culture experiment was carried out where four farming systems were tested: monoculture of mud crab, Scylla serrata (T1), polyculture of mud crab, with mullet Mugil cephalus and shrimp Penaeus indicus (T2), polyculture of mud crab with mullet, shrimp and oyster Crassostrea cuttackensis (T3), polyculture of mud crab with mullet, shrimp, oyster along with periphyton net (T4) covering 10% of the water spread area. There was no significant difference in the growth performances of mud crab, shrimp and oyster among the treatment but a significantly higher (p < .05) final average body weight (ABW) of M.cephalus was recorded in T4 (121.19 ± 2.09 g). Production considering only the fed animals (excluding oyster) was significantly (p < .05) higher in T4 (2,115 kg/ha) compared to other treatments. The overall water quality parameters do not vary significantly (p > .05) among the treatment ponds. Although there was no significant difference in total ammonia nitrogen (TAN) and nitrite‐N, highest value was recorded in T2 (56.23 ± 39.47 µg/L and 185.53 ± 110.71 µg/L) and T1 (55.78 ± 32.26 µg/L and 180.83 ± 103.65 µg/L). The results from the current experiment based on water quality and growth of animals showed that there is no negative interaction between the mud crab and other animals stocked in the polyculture pond which indicated that polyculture provides an efficient and sustainable utilization of resources.     

Growth and survival of the juvenile yellowleg shrimp Farfantepenaeus californiensis cohabiting with the green feather alga Caulerpa sertularioides at different temperatures

This study was performed to determine the growth and survival patterns of the juvenile yellowleg shrimp Farfantepenaeus californiensis cohabiting with the green feather alga Caulerpa sertularioides over a range of temperatures (18, 22, 25, 28 and 32°C) found throughout the year in the Gulf of California. From an initial weight of 46 ± 10 mg, shrimp cohabiting with green feather algae increased in weight by an average of 0.57 (±0.07), 5.44 (±0.45), 6.36 (±0.37), 7.66 (±0.26) and 5.96 (±0.59) g at 18, 22, 25, 28 and 32°C, respectively, whereas shrimp grown without seaweed increased in weight by an average of 0.28 (±0.026), 2.66 (±0.24), 3.15 (±0.49), 4.00 (±0.67), and 3.54 (±0.09) g respectively. Statistically significant differences were observed for the growth rates of juvenile yellowleg shrimp in the presence of C. sertularioides and peak growth was observed at 28°C in experiments with macroalgae. No significant differences were observed for shrimp survival except at 32°C without macroalgae, where survival was lower. These results suggest a beneficial and growth‐promoting effect of cohabitation with live C. sertularioides on F. californiensis.     

Effects of the commercial probiotic Lactobacillus casei on the growth,protein content of skin mucus and stress resistance of juveniles of the Porthole livebearer Poecilopsis gracilis (Poecilidae)

A 11‐week feeding trial was carried out to determine the effects of the probiotic bacteria Lactobacillus casei from the commercial product Yakult^® on the growth performance, proximal composition, protein content of skin mucus and stress resistance of juvenile Porthole livebearer Poeciliopsis gracilis. Triplicate groups of 15 juveniles per tank with an initial weight of 47 ± 9 mg (mean ± standard deviation) were fed with Artemia nauplii enriched with the probiotic, by using the bacteria cells plus the fermented milk (group ProN) and the other (group ProC) by using only the bacterial cells, eliminating the fermented milk by centrifugation. A control of fish was set up, by feeding non‐enriched Artemia nauplii. Growth performance and survival rates did not show significantly differences among the treatments and control group, but a slightly tendency of higher values for body weight, weight gain and specific growth rate was observed in the juveniles of ProC treatment. Whole body proximate composition did not show significant differences among the groups, but higher values of protein and lipid contents were observed in the groups fed with the probiotic. Content of protein in the skin mucus were significantly higher in the ProC treatment than control group. Recovery rates after an air‐dive test were significantly higher on the fish fed with the probiotic cells than the control group. These results show that L. casei might be used as a probiotic for fish and would help during the culture of juvenile of the Porthole livebearer P. gracilis.     

Effects of different carbon sources and dietary protein levels in a biofloc system on growth performance,immune response against white spot syndrome virus infection and cathepsin L gene expression of Litopenaeus vannamei

A 5‐week study was performed to evaluate the effect of spoilage date extract (SDE) as the biofloc carbon source on Litopenaeus vannamei (5.4 ± 0.3 g) performance. The two levels of dietary protein (15% and 25% crude protein) and two carbohydrate sources (molasses‐M and SDE‐P) were tested including: M15, M25, P15 and P25. The minimum (0.2 ± 0.0 mg/L) and the maximum (0.5 ± 0.0 mg/L) of total ammonia nitrogen were observed in the P15 and M25 groups respectively. The highest protein efficiency ratio (6.1 ± 0.3) and protein productive value (112.3 ± 5.8%) were found in the P15 group (p < 0.05). No significant difference was found between biofloc treatments in the expression of cathepsin L gene in hepatopancreas (p > 0.05). The number of total haemocyte count (THC), semigranular cells (SGC) and granular cells (GC) of shrimp in SDE‐based biofloc treatments was relatively higher than those in molasses‐based biofloc treatments. Following the white spot syndrome virus (WSSV) challenge, a significant decrease in THC, SGC, GC and hyaline cell values was observed in all treatments (p = 0.001). Plasma biochemical parameters were significantly influenced by dietary protein levels, biofloc carbon sources as well as WSSV challenge test. In conclusion, SDE successfully could be used as an alternative carbon source for establishing a biofloc system in L. vannamei production.     

Successful rearing of whiteleg shrimp Litopenaeus vannamei larvae fed a desiccation‐tolerant nematode to replace Artemia

The nematode Panagrolaimus sp. was tested as live feed to replace Artemia nauplii during first larval stages of whiteleg shrimp Litopenaeus vannamei. In Trial 1, shrimp larvae were fed one of four diets from Zoea 2 to Postlarva 1 (PL1): (A) Artemia nauplii, control treatment; (NC) nematodes enriched in docosahexaenoic acid (DHA) provided by the dinoflagellate Crypthecodinium cohnii; (N) non‐enriched nematodes; and (Algae) a mixture of microalgae supplemented in C. cohnii cells. In Trial 2, shrimp were fed (A), (NC) and a different treatment (NS) with nematodes enriched in polyunsaturated fatty acids (PUFAs) provided by the commercial product S.presso^®, until Postlarva 6 (PL6). Mysis 1 larvae fed nematodes of the three dietary treatments were 300 μm longer (3.2 ± 0.3 mm) than control larvae. At PL1, control shrimp were 300 μm longer (4.5 ± 0.3 mm) than those fed DHA‐enriched or PUFAs‐enriched nematodes. No differences were observed in length and survival at PL6 between control larvae and those fed DHA‐enriched nematodes (5.1 ± 0.5 mm; 33.1%–44.4%). Shrimp fed microalgae showed a delay in development at PL1. This work is the first demonstration of Panagrolaimus sp. suitability as a complete substitute for Artemia in rearing shrimp from Zoea 2 to PL6.     

Effect of biofloc technology (BFT) on the early postlarval stage of pink shrimp <Emphasis Type="Italic">Farfantepenaeus paulensis</Emphasis>: growth performance,floc composition and salinity stress tolerance

Biofloc rearing media provides a potential food source for shrimp reared in limited or zero water exchange systems. This culture system is environmentally friendly as it is based on limited water use and minimal effluent is released into the surrounding environment. In this study, we evaluated the survival, growth performance and salinity stress tolerance of pink shrimp Farfantepenaeus paulensis postlarvae reared from PL₁₀ to PL₂₅ in a biofloc technology limited water exchange system. PL (mean ± SD weight and length of 14 ± 10 mg and 8.10 ± 0.7 mm, respectively) were reared in nine 40-L plastic tanks with a stocking density of 10PL/L. Three culture treatments were applied (1) culture in the presence of bioflocs and commercial feed supply (FLOC + CF); (2) culture in the presence of biofloc without feed supply (FLOC) and (3) culture in clear water with feed supply (control). Final biomass and survival were significantly higher in FLOC + CF treatment than the control (P < 0.05), but did not differ from FLOC. PL reared in the FLOC + CF treatment achieved a significantly higher final weight, weight gain and length in comparison with the other two treatments (P < 0.05). No significant difference (P > 0.05) between treatments was found for salinity tolerance over 24 and 48 h durations. The proximate analysis of floc shown high levels of crude protein (30.4%), but low levels of crude lipids (0.5%). The continuous availability of bioflocs had a significant effect on growth and survival of F. paulensis postlarvae cultured in BFT nursery systems.     

Identification of potential general markers of disease resistance in Exopalaemon carinicauda via three‐round challenge selection with an acute hepatopancreatic necrosis disease‐causing strain of Vibrio parahaemolyticus

Sixteen candidate disease‐resistant parameters were selected through which to evaluate the acute hepatopancreatic necrosis disease (AHPND)‐resistant capability of Exopalaemon carinicauda after three generations of selection for AHPND‐causing strain of Vibrio parahaemolyticus (VP_AHPND) resistance in our previous study. However, these parameters required further verification. In this study, another AHPND‐resistant E. carinicauda series was obtained through a short‐term selection procedure, consisting of three virulent challenge rounds of selection (about three‐week interval for each challenge) with VP_AHPND infection. After this selection, the survival rate at 144 hr post infection (hpi) increased from 23.33% to 37.78% and the observed 48‐hr LD₅₀ of VP_AHPND to shrimp increased from 10^5.5 cfu/ml to 10^6.5 cfu/ml. Then, the immune response of this AHPND‐resistant E. carinicauda was studied using the 16 candidate AHPND‐resistant parameters selected for in our previous study. The improved VP_AHPND clearance rate in hpi, increased total haemocyte counts, haemocyanin concentration, alkaline phosphatase activity and expressions of six immune‐related genes (Tollip and ALF in haemocytes and hepatopancreas; lysozyme, crustin and cathepsin B in hepatopancreas; and LGBP in haemocytes) at 24 hpi after the three‐round challenge selection suggest that these immune parameters may be reliable markers for the evaluation of the physiological status and potential AHPND‐resistant phenotypes in E. carinicauda.     

Growth parameters of whiteleg shrimp Litopenaeus vannamei and red seaweed Gracilaria corticata in integrated culturing method under zero water exchange system

Growth parameters of whiteleg shrimp Litopenaeus vannamei and red seaweed Gracilaria corticata were measured using integrated culturing method under zero‐water exchange system in a 45‐day period. A 2 × 3 factorial design was used with two levels of shrimp stocking densities and three levels of seaweed weight densities. G. corticata was cultured on a net tied to a round polyethylene frame. Culture tanks were filled with 750‐L filtered seawater. A 40‐W compact fluorescent lamp was hung over each tank to provide adequate and sufficient light for seaweed growth. Growth parameters of shrimp and seaweed such as specific growth rate (SGR), weight gained (WG) and average daily growth (ADG) were computed based on the initial and final weight of shrimp and seaweed. The maximum and minimum SGR of L. vannamei (1.97 and 1.69%/day) were observed in treatment S₁A₃ (25 shrimp/m² and 400 g seaweed/m²) and S₂A₁ (50 shrimp/m² without seaweed) respectively. The best survival rate (94.67 ± 1.33%), WG (129.9 ± 2.9%) and feed conversion ratio (1.67 ± 0.04) were also observed in treatment S₁A₃. The SGR of G.corticata in the treatment S₁A₃ (1.97 ± 0.00%/day) was significantly higher, compared to others. Strong positive correlations were obtained between the density of G. corticata and the growth parameters of L. vannamei. The red seaweed G. corticata could boost the growth parameters, survival rate and total production of L. vannamei under zero‐water exchange system.     

Effects of dietary medicinal herbs and Bacillus on survival, growth, body composition, and digestive enzyme activity of the white shrimp Litopenaeus vannamei

The basal diet (C), with 0.20% medicinal herbs (M) and 0.30% Bacillus (BM1), with 0.10% medicinal herbs and 0.15% Bacillus (BM2), and with 0.30% Bacillus (B), was used to feed white shrimps (Litopenaeus vannamei) (1.91 ± 0.03 g) in order to assess survival, growth, body composition, and digestive enzyme activity. At the end of the feeding trial, survival ranged from 95.83 to 98.33% with no significant difference (P > 0.05) among all groups. Growth measured as weight gain was significantly (P < 0.05) higher in shrimp fed with BM2, BM1, and M compared to that of C. However, no significant differences were found among B, BM1, and M. In the case of specific growth rate, the shrimp fed with BM1 and BM2 exhibited significantly (P < 0.05) higher values than that of C. The contents of body moisture, crude protein, and ash seemed to be unaffected by the feed supplements, though lipid content was found to be significantly (P < 0.05) different among the treatments. The shrimp fed with BM1 and BM2 had the lowest and highest lipid contents, respectively. The digestive enzyme activity assessed using shrimp hepatopancreas revealed that the activities of amylase and protease in shrimp fed with BM2 were significantly (P < 0.05) higher than those of C at the end of the 2nd and 6th weeks. However, better performance of the specific amylase activity was shown by the shrimp fed with B at the end of the 8th week.     

Effects of stocking density on the survival,growth and physical injury of Marsupenaeus japonicus juveniles in a flowing water aquaculture system

Stocking density is a biotic factor affecting the production of cultivated animals in aquaculture. Herein, a rearing trial was conducted to investigate the impact of stocking density on the survival, growth performance and physical injury of Marsupenaeus japonicus juveniles in a flowing water aquaculture system. Five stocking densities were examined in this study, that is, 10, 20, 40, 80 and 160 individuals/m². Throughout the experiment, ammonia nitrogen and nitrite concentrations ranged from 0.02 ± 0.006 mg/L to 0.08 ± 0.035 mg/L and 0.002 ± 0.001 mg/L to 0.076 ± 0.021 mg/L respectively. The survival rate, specific growth rate (SGR), weight gain (WG), absolute growth rate (AGR) and coefficient of variation for weight (CV) across the stocking densities ranged from 90.38 ± 3.20% to 94.33 ± 4.73%, 1.42 ± 0.16%/day to 1.53 ± 0.05%/day, 1.09 ± 0.19 g to 1.15 ± 0.16 g, 0.018 ± 0.003 g/day to 0.019 ± 0.004 g/day and 16.21 ± 5.78% to 35.09 ± 10.68% respectively. Within the investigated densities, the survival rate and the abovementioned growth parameters were not significantly (p > .05) affected by the stocking density, consequently, a higher stocking density resulted in a significantly (p < .05) greater final biomass. The results regarding physical injury showed that the antennal breakage rate displayed a tendency of a positive correlation with the stocking density. Overall, the current study provides basic data for establishing a viable intensive farming system for M. japonicus and a promising indicator for easily assessing the crowding stress status of M. japonicus.