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1.
The present study assessed the effects of different types of feeds and salinity levels on water quality, growth performance, survival rate and body composition of the Pacific white shrimp, Litopenaeus vannamei, juveniles in a biofloc system. Shrimp juveniles (2.56 ± 0.33 g) were cultured for 35 days in 300 L fibreglass tanks (water volume of 180 L) with a density of 1 g/L in six treatments. Three sources of feed (100% formulated feed, mixture of 66.6% formulated diet and 33.3% wet biofloc, and 100% wet biofloc) and two levels of salinity (10 and 32 ppt) were considered in two control groups and four biofloc treatments. Water quality parameters in the biofloc treatments were significantly better than control groups (p < .05). The highest increase in growth performance and survival rate were obtained in salinity of 32 ppt and mixed feed sources. Analysing the proximate composition of body shrimp indicates an increase in lipid and ash levels in biofloc treatments, which was more evident in the salinity of 32 ppt. In addition, the proximate analysis of shrimp body showed significant differences between biofloc treatments and control groups (p < .05). The highest FCR was found in the treatment with salinity level of 10 ppt and fed only with floc. Overall, it was found that the artificial diet supplemented with biofloc at the salinity of 32 showed better performance in the juvenile stage of Pacific white shrimp.  相似文献   

2.
A 35‐day feeding experiment was conducted to investigate the effects of different carbon sources addition on nutritional composition and extracellular enzymes activity of bioflocs, and digestive enzymes activity and growth performance of Litopenaeus vannamei juveniles (average 5.52 ± 0.21 g) in zero‐water exchange culture tanks. Molasses, corn flour and wheat bran were used as carbon sources and added into the tanks to promote the development of bioflocs during the experiment. During the entire experiment, good water quality and biofloc development were achieved under the addition of different carbon sources. At the end of the experiment, the proximate composition and extracellular enzymes activities of the collected bioflocs from seven biofloc groups were influenced by the addition of the different carbon sources. Meanwhile, the specific activities of protease, amylase, lipase and cellulase in the hepatopancreas, stomach and intestine of the shrimp showed differences among the seven biofloc groups, and most of them were significantly higher than those obtained in the control group (P < 0.05). There were differences in the performance (growth and FCR) of the shrimp among the seven biofloc groups, and all of them were significantly better than those obtained in the control group (P < 0.05). Based on the results of this study, 60% molasses + 20% corn flour + 20% wheat bran could be an appropriate formula of the addition of carbon sources for intensive culture of L. vannamei (mainly in terms of growth and FCR) in zero‐water exchange culture tanks.  相似文献   

3.
This study aimed to investigate the development and bioactive compounds of biofloc promoted by adding molasses and wheat bran to zero‐water exchange culture tanks and their effects on physiological parameters and growth performance of juvenile Litopenaeus vannamei (initial weight: 6.8 ± 0.4 g). Different combinations of molasses and wheat bran were added as carbon sources: T1, 100% molasses; T2, 50% molasses + 50% wheat bran; T3, 25% molasses + 75% wheat bran. Clear water tanks with water exchange served as the control group (control). After the 30‐d experiment, the development of biofloc in terms of total suspended solids (TSS) and biofloc volume (BFV) showed significant differences in the three biofloc treatments, especially the highest levels of TSS and BFV observed in T3. The levels of poly‐beta‐hydroxybutyrate or polysaccharide in the biofloc of T1 and T2 were significantly higher than those in T3. Meanwhile, compared with the control group, most of the immune and antioxidant parameters and growth performance of shrimp were significantly enhanced in biofloc treatments, especially in T1 or T2. In conclusion, different carbon sources could effectively affect the development and bioactive compounds of biofloc, which could improve physiological health status and growth performance of shrimp in zero‐water exchange systems.  相似文献   

4.
Closed recirculating aquaculture systems (RAS) offer advantages over traditional culture methods including enhanced biosecurity, the possibility of indoor, inland culture of marine species year‐round and potential marketing opportunities for fresh, never‐frozen seafood. Questions still remain regarding what type of aquaculture system may be best suited for the closed‐system culture of marine shrimp. In this study, shrimp (Litopenaeus vannamei) were grown in clear‐water RAS and in biofloc‐based systems. Comparisons were made between the system types with respect to water quality, shrimp production and stable isotope dynamics used to determine the biofloc contribution to shrimp nutrition. Ammonia and nitrite concentrations were higher, and shrimp survival was lower in the biofloc systems. Although stable isotope levels indicated that biofloc material may have contributed 28% of the carbon and 59% of the nitrogen in shrimp tissues, this did not correspond with improved shrimp production. Overall, the water column microbial communities in biofloc systems may be more difficult to manage than clear‐water RAS which have external filters to control water quality. Biofloc does seem to offer some nutritional contributions, but exactly how to take advantage of that and ensure improved production remains unclear.  相似文献   

5.
Superintensive shrimp culture in zero‐exchange, biofloc‐dominated production systems is more biosecure and sustainable than traditional shrimp farming practices. However, successful application of this technology depends upon optimizing dietary formulations, controlling Vibrio outbreaks, and managing accumulative changes in water quality and composition. A 49‐d study investigated the effect of two commercial feeds of differing protein content and an indoor limited‐exchange, biofloc‐dominated culture environment on Litopenaeus vannamei performance and tissue composition, water quality and ionic composition, and Vibrio dynamics. Juveniles (5.3 g) were stocked at 457/m3 into four 40 m3 shallow raceways containing biofloc‐dominated water and fed one of two commercial feeds with differing protein content, 35 or 40%. Shrimp performance, Vibrio populations, and changes in shrimp and culture water composition were monitored. There were no significant differences (P > 0.05) in shrimp performance (survival, weight, growth, specific growth rate, total biomass, yield, feed conversion ratio, and protein efficiency ratio) or proximate composition between feed types. The 40% protein feed resulted in higher culture water nitrate and phosphate concentrations, alkalinity consumption and bicarbonate use, and higher phytoplankton density. The presence of Vibrio, specifically Vibrio parahaemolyticus, reduced shrimp survival. This survival decrease corresponded with increased culture water Vibrio concentrations. Culture water K+ and Mg2+ increased significantly (P < 0.05), and Sr2+, Br?, and Cl? decreased significantly (P < 0.05) over time. While Cu2+ and Zn2+ did increase in shrimp tissue, no heavy metals accumulated to problematic levels in culture water or shrimp tissue. These results demonstrate the importance of monitoring Vibrio populations and ionic composition in limited‐exchange shrimp culture systems.  相似文献   

6.
Litopenaeus vannamei (Boone) grown in ponds are exposed to salinities of less than 5 g L?1 during inland shrimp culture or to more than 40 g L?1 from evaporation and reduced water exchange in dry, hot climates. However, dietary requirements for shrimp grown in low or high salinities are not well defined, particularly for fatty acids. Feeding shrimp postlarvae with highly unsaturated fatty acids (HUFA) enhances tolerance to acute exposure to low salinity, as a result of better nutritional status, or/and specific effects of HUFA on membrane function and osmoregulation mechanisms. This study analysed the effect of HUFA supplementation (3% vs. 34%) on L. vannamei juveniles reared for 21 days at low (5 g L?1), medium (30 g L?1) and high salinities (50 g L?1). Juveniles grown at 5 g L?1 had lower survival compared with controls (30 g L?1) or shrimp grown at 50 g L?1, but no significant effect on survival was observed as a result of HUFA enrichment. In contrast, growth was significantly lower for shrimp grown at 50 g L?1, but this effect was compensated by the HUFA‐enriched diet. Osmotic pressure in haemolymph was affected by salinity, but not by HUFA enrichment. Shrimp fed HUFA‐enriched diets had significantly higher levels of eicosapentaenoic acid and docosahexaenoic acid in hepatopancreas and gills. These results demonstrate that growth at high salinities is enhanced with diets containing high HUFA levels, but that HUFA‐enriched diets have no effect on shrimp reared at low salinities.  相似文献   

7.
This experiment was carried out to investigate the effect of feeding low protein diets (~20BFd20.13; ~22BFd22.20; ~24BFd24.32, and ~26BFd26.44) in the presence of the biofloc on the growth performance and feed utilization of (Fenneropenaeus indicus) in comparison with commercial feed of 35% CP as control. The present study was based on application of genetic, nutritional and pathological tools. The biofloc was developed in the low protein diet using molasses as a carbon source. Fifty juveniles F. indicus with an average body weight of 0.52?±?0.03 g were stocked in 50 L plastic tanks. Low protein diets and the control were tested in three replicates over a 112 days feeding trial. There were significant differences in protein, amino acids profile, lipids and fatty acids profile between the control and low diets group in the presence of the biofloc. However, less variation was noticed in the whole body composition (protein, amino acid profile, lipids and fatty acid profiles) of the shrimp between the control and low diets groups in the presence of the biofloc. There were no significant differences in final weight between control and low diets groups. Same trend was noted in the SGR, which did not vary significantly between low protein diets and control. However, the utilization of the biofloc by shrimp as a feed source was evident by the significant differences (P<?0.05) in FCR between low protein diets and control. There was a significant difference in the shrimp survival (%) (P<?0.05) between the low protein diets and the control which ranged between 86.66 % and 66.66 %, respectively. The development of biofloc significantly reduced the TAN, nitrate NO3-N and nitrite NO2-N levels in the low protein diets tanks. Diagnostic of mortality cases revealed that biofloc can serve as a biosecurity system for shrimp farmimg. RAPD-PCR were used to study the epidemiology of Vibrio parahaemolyticus responsible for early mortality syndrome (EMS) isolated from the water of culture system. The OPC5 (GATGACCGCC) primer produced bands ranged from 1 to 8 with sizes from 0.2–5.0 kb.  相似文献   

8.
The effects of four different ionic composition low salinity water (T1, T2, T3, and T4), on growth and survival of Litopenaeus vannamei marine shrimp juveniles were investigated. Shrimp culture in seawater (Tm) was used as control treatment. The results indicated that there were no significant difference (P < 0.05) in growth, survival, production, and feed conversion ratio (FCR) of L. vannamei juveniles reared in the different treatments, but significant differences (P < 0.05) were observed between each of them when compared with seawater (Tm). After 84 days, culture shrimp grew from 0.02 to 7.58 g in T1. The lowest growth rate was attained in T3 (0.57 g/week), in which potassium and calcium ions concentrations were the lowest (0.58 and 28.00 mg/L, respectively). The recorded survival rate (76.35% to 79.55%) is considered well for the 84 days growout period, although it was 7.6% lower than that recorded in the control treatment. Although there were no significant differences (P < 0.05) in growth with respect to the ionic composition of the four treatments, there was a trend of increasing growth in relation with the ionic ratio found in the seawater (Tm). This aspect should be evaluated more closely in future research.  相似文献   

9.
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.  相似文献   

10.
The use of non‐marine arachidonic acid (ArA) and docosahexaenoic acid (DHA) as highly unsaturated fatty acid (HUFA) enrichments was evaluated as complete replacements for marine fish oil in practical diets formulated with solvent‐extracted soybean meal (SESM). Litopenaeus vannamei juveniles (0.59 g) were reared over 84 days in an outdoor tank system with no water discharge. Fishmeal was replaced with SESM, while fish oil was replaced with HUFA‐rich algal cells, alternative oil and/or fermentation products. Spray‐dried Schizochytrium algal cells (Schizomeal‐Hi DHA) served as the DHA enrichment source. Oil extracted from Mortierella sp. was used as the ArA enrichment (AquaGrow® ArA). DHA and ArA sources (Advanced BioNutrition Corp., Columbia, MD, USA) were non‐marine products obtained from a commercial supplier. Five diets were formulated with ArA inclusion levels of 0, 0.65, 1.3, 2.6 and 5.2 g kg?1. In addition, one diet was formulated to be DHA deficient and another was formulated with menhaden fish oil (control). Different inclusion levels of non‐marine ArA had no effect on survival or growth. Shrimp fed the non‐marine HUFA‐supplemented diets had lower average weight compared to shrimp offered the diet containing fish oil. No differences were detected in average weights of shrimp offered the ArA‐deficient and ArA‐supplemented diets.  相似文献   

11.
In a Biofloc Technology System (BFT), there is constant biofloc formation and suspended solids accumulation, leading to effects on water quality parameters that may affect the growth performance of cultured shrimp. This study aimed to analyse during biofloc formation the effect of different total suspended solids (TSS) levels on water quality and the growth performance of Litopenaeus vannamei shrimp in a BFT system. A 42‐day trial was conducted with treatments of three ranges of TSS: 100–300 mg L?1 as low (TL), 300–600 as medium (TM) and 600–1000 as high (TH). The initial concentrations of 100 (TL), 300 (TM) and 600 mg L?1 (TH) were achieved by fertilization before starting the experiment. Litopenaeus  vannamei juveniles with an average weight of 4.54 ± 1.19 g were stocked at a density of 372 shrimp m?3. Physical and chemical water parameters and shrimp growth performance were analysed. After 6 weeks, TSS mean concentrations were 306.37, 532.43 and 745.2 mg L?1 for, respectively, TL, TM and TH treatments. Significant differences (P < 0.05) were observed in TSS, settleable solids, pH, alkalinity and nitrite, especially between the TL and TH treatments. Similarly, differences (P < 0.05) were observed in the growth performance parameters, specifically final weight, survival, feed conversion and productivity. The water quality parameters at lower range of total suspended solids concentration (TL) treatment resulted in a better performance of L. vannamei in the BFT system. The maintenance at range of 100–300 mg L?1 TSS is thus important to the success of shrimp culture.  相似文献   

12.
To evaluate effect of substrate integration in biofloc based system, a 52‐day growth experiment was conducted using black tiger shrimp, Penaeus monodon juveniles (3.32 ± 0.07 g). The factorial design consisted of floc, F (with or without) as first factor and substrate (bamboo mat, B; nylon mesh, N; and without substrate) as second factor. This resulted six treatments; F + B, F + N, F, B, N and a control without biofloc and substrate. Shrimps were stocked at 110 nos. m–3 in Fibre Reinforced Plastic (FRP) tanks and, rice flour was used as carbon source in biofloc based treatments. Incorporation of nylon mesh and bamboo mat in biofloc system trapped 31.3%–38.6% and 8.5%–13.5% total suspended solids respectively and reduced bottom solid deposition. Among the substrate based groups, significantly better development of biofilm with higher microbial population noticed in F + B compared with nylon mesh. Similarly, significantly higher final growth (p < 0.01) was recorded in F + B system followed by F + N while no significant difference in body weight recorded among floc, F or substrate based groups (B, N). Biofloc and substrate integration (F + B and F + N) resulted significantly (p < 0.01) lower feed conversion ratio compared to control and floc. Incoporation of bamboo substrate in biofloc, (F + B) improved shrimp immune responses through higher hemocyte counts and prophenoloxidase activity compared to other treatments. The study revealed that integration of substrate in the biofloc system improved growth performance, FCR and immune parameters in shrimp by trapping the suspended biofloc particles, better water quality parameters, enhanced biofilm growth and provision of quality natural food.  相似文献   

13.
The co‐culture of juvenile sea cucumber Holothuria scabra (Jaeger), or ‘sandfish’, with juvenile blue shrimp Litopenaeus stylirostris (Stimpson) was tested by growing groups in co‐culture and monoculture for 3 weeks in tanks with enriched sand substratum. Feed was supplied on trays, accessible only to shrimp. Survival of shrimp and sandfish was high in all treatments (73–100%). Growth of shrimp did not differ between monoculture and co‐culture, but sandfish grew significantly slower in co‐culture (P=0.03), although their sand burying and surface foraging were apparently unaffected by shrimp (P=0.76). However, shrimp increased the levels of total ammonia‐N in tanks, which related inversely with sandfish growth (P=0.04). Conversely, sandfish did not appear to lower the water quality for shrimp culture. While sandfish bioturbate sediments and eat organic deposits, the juveniles did not significantly reduce the organic content of sand in tanks. Co‐culturing juveniles of the two species in earthen ponds appears feasible, with no detriment to shrimp production, presenting a cost‐effective method for growing sandfish to larger sizes for restocking. These findings underpin further studies to test the viability of commercial co‐culture of sandfish with blue shrimp at later stages in the production cycle of shrimp.  相似文献   

14.
Despite the shrimp ability to obtain additional nutrients from food organisms endogenously produced within the ‘green water’ system has been suggested as one of the causes for the better performance of Pacific white shrimp reared in ‘green water’ in comparison with ‘clear water’, the nutritional components responsible for these effects have yet to be determined. The present study aims to understand the importance of natural food organisms in zero‐water exchange systems as source of essential fatty acids for the Pacific white shrimp Litopenaeus vannamei. Five treatments were tested: two conducted in mesocosms systems with shrimp‐fed diets containing either fish oil (FO) or olive oil, and another three conducted in clear water with shrimp‐fed diets containing either olive oil, a docosahexaenoic acid (DHA)‐rich oil or an arachidonic acid (ARA)‐rich oil. The presence of higher levels of fatty acids 16:1n‐7, 17:1, 20:4n‐6, 20:3n‐3 and 22:5n‐6, characteristic of floc lipids, in shrimp reared in mesocosms denoted their assimilation from the floc. Substitution of FO by olive oil in diets for shrimp reared in mesocosms did not affect growth or survival. Survival and growth of shrimp reared in mesocosms was better than those reared in clear water and fed an olive oil diet, whereas DHA or ARA enrichment of non‐fish oil (NFO) diet improved survival of shrimp reared in clear water. Higher survival rate, triglyceride and DHA content in whole body and eyes of shrimp fed a DHA‐rich diet suggests that under these conditions, in clear water, it is necessary to include at least 4.8 g kg?1 DHA in diet dry weight. ARA enrichment seemed to negatively affect growth. The nutritional contribution of the floc to shrimp in mesocosm culture reduces or eliminates the need for a dietary source of FO and illustrates the importance of DHA and ARA to enhance shrimp survival in clear water conditions.  相似文献   

15.
The objective of the study was to examine the effects of biofloc technology on the muscle proteome of Litopenaeus vannamei. Two biofloc treatments and one control were compared: biofloc‐based tanks under zero‐water exchange fed with 150 g/kg crude protein (BF15), or with 250 g/kg crude protein (BF25) diets, and clear water tanks with 50% of daily water exchange stocked with shrimp fed with similar amount of a 250 g/kg crude protein diet, referred to as control. The shrimp (5.28 ± 0.42 g) were divided into the 300‐L fibreglass tanks (water volume of 200 L) at a density of 35 shrimp per tank and were cultured for 35 days. The biofloc groups displayed better growth and survival compared to the control. The muscle tissue from the control and BF25 groups was subjected to proteomic analysis. Lactate dehydrogenase, enolase, arginine kinase, mitochondrial ATP synthase subunit alpha, mitochondrial ATPase inhibitor factor 1 precursor, serpin 3 and myeloid differentiation factor 88 had an increased abundance in the BF25 group, while myosin heavy chain type 1 and myosin heavy chain type 2 showed a decreased abundance. The results indicate that biofloc technology could alter the expression of proteins involved in structure, metabolism and immune status of cultured shrimp.  相似文献   

16.
Pacific white shrimp, Litopenaeus vannamei, exhibit a remarkable ability to tolerate low‐salinity environments, facilitating its culture far from coastal areas using various production systems at salinities less than 15 g/L. Recirculating aquaculture systems (RAS) and biofloc systems are usually operated using reconstituted sea salt (RSS), which is a considerable financial burden to commercial producers due to its higher price. Current study was carried out with the objective of testing the efficacy of a low‐cost salt solution to replace expensive RSS to grow shrimp under laboratory conditions. Low‐cost salt mixture (LCSM) was formulated to yield sodium, potassium, calcium and magnesium concentrations closely comparable to that of diluted seawater using agriculture grade sodium chloride, magnesium chloride, magnesium sulphate, potassium oxide, calcium chloride and sodium bicarbonate. Growth trials were conducted at three different salinities of 3, 6 and 15 g/L, incrementally replacing RSS with LCSM (0, 2.5, 25, 50, 75 and 100%) at four replicates per treatment. Twenty juvenile shrimp were reared for 42 days in 150 L polyethylene tanks. Ionic profile of water, ionic profile and osmolality of shrimp haemolymph were determined to justify growth and survival data through analysing ionic variations and osmoregulatory capacity of shrimp. At the conclusion, no significant differences were observed in survival, growth, osmoregulation and levels of cations in shrimp haemolymph between RSS and LCSM treatments at all salinities examined. Results reflect the potential use of LCSM to replace RSS which could be an excellent solution to bring down the cost of production in inland shrimp aquaculture.  相似文献   

17.
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18.
An eight‐week feeding trial was conducted to evaluate the contribution of biofloc on dietary lipid requirement in whiteleg shrimp Litopenaeus vannamei. Five diets with graded levels of dietary lipid (45, 60, 90, 120 and 150 g/kg) were fed to juvenile shrimp. Final weight, weight gain and specific growth rate of shrimp fed diets with 60, 90 and 120 g/kg lipid levels were significantly higher than those of shrimp fed diets with lipid levels 45 and 150 g/kg (p < .05). Feed efficiency and protein efficiency ratio of shrimp fed 60, 90 and 120 g/kg were higher than those fed 150 g/kg diet. Plasma total cholesterol and triglyceride levels were lower in shrimp fed 45 g/kg compared with those fed the 90 g/kg (p < .05). Also, lysozyme activity for 90 g/kg group was higher than the 15 g/kg group. Hepatopancreas lipase and amylase activities of shrimp fed 90 and 120 g/kg diets were significantly higher than those of shrimp fed 45 and 150 g/kg diets. Broken‐line regression analysis for weight gain indicated that the dietary lipid requirement of whiteleg shrimp juveniles reared in a biofloc system was estimated to be higher than 56 g/kg but <60 g/kg.  相似文献   

19.
The experiment was conducted with three biofloc treatments and one control in triplicate in 500 L capacity indoor tanks. Biofloc tanks, filled with 350 L of water, were fed with sugarcane molasses (BFTS), tapioca flour (BFTT), wheat flour (BFTW) and clean water as control without biofloc and allowed to stand for 30 days. The postlarvae of Litopenaeus vannamei (Boone, 1931) with an Average body weight of 0.15 ± 0.02 g were stocked at the rate of 130 PL m?2 and cultured for a period of 60 days fed with pelleted feed at the rate of 1.5% of biomass. The total suspended solids (TSS) level was maintained at around 500 mg L?1 in BFT tanks. The addition of carbohydrate significantly reduced the total ammonia‐N (TAN), nitrite‐N and nitrate‐N in water and it significantly increased the total heterotrophic bacteria (THB) population in the biofloc treatments. There was a significant difference in the final average body weight (8.49 ± 0.09 g) in the wheat flour treatment (BFTW) than those treatment and control group of the shrimp. Survival of the shrimps was not affected by the treatments and ranged between 82.02% and 90.3%. The proximate and chemical composition of biofloc and proximate composition of the shrimp was significantly different between the biofloc treatments and control. Tintinids, ciliates, copepods, cyanobacteria and nematodes were identified in all the biofloc treatments, nematodes being the most dominant group of organisms in the biofloc. It could be concluded that the use of wheat flour (BFTW) effectively enhanced the biofloc production and contributed towards better water quality which resulted in higher production of shrimp.  相似文献   

20.
The bioflocs technology (BFT) for shrimp production has been proposed as a sustainable practice capable of reducing environmental impacts and preventing pathogen introduction. The microbial community associated with BFT not only detoxifies nutrients, but also can improve feed utilization and animal growth. Biofloc system contains abundant number of bacteria of which cell wall consists of various components such as bacterial lipopolysaccharide, peptidoglycan and β‐1, 3‐glucans, and is known as stimulating nonspecific immune activity of shrimp. Bioflocs, therefore, are assumed to enhance shrimp immunity because they consume the bioflocs as additional food source. Although there are benefits for having an in situ microbial community in BFT systems, better understanding on these microorganisms, in particular molecular level, is needed. A fourteen‐day culture trial was conducted with postlarvae of Litopenaeus vannamei in the presence and absence of bioflocs. To determine mRNA expression levels of shrimp, we selected six genes (prophenoloxidase1, prophenoloxidase2, prophenoloxidase activation enzyme, serine proteinase1, masquerade‐like proteinase, and ras‐related nuclear protein) which are involved in a series of responses known as the prophenoloxidase (proPO) cascade, one of the major innate immune responses in crustaceans. Significant differences in shrimp survival and final body weights were found between the clear water and in the biofloc treatments. mRNA expression levels were significantly higher in the biofloc treatment than the clear water control. These results suggest that the presence of bioflocs in the culture medium gives positive effect on growth and immune‐related genes expression in L.vannamei postlarvae.  相似文献   

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