Juvenile Litopenaeus Vannamei Research Articles

Use of passive acoustic monitoring to evaluate the effects of a feed effector on feeding behavior, growth performance, and salinity stress tolerance of Litopenaeus vannamei

Pacific whiteleg shrimp is the topmost aquacultured species produced in the world. However, shrimp feeding behavior results in unnecessary expenditures, as some of the feed offered is not entirely consumed. Nowadays, aquaculture has become more accepting of using animal by-products such as poultry meal as a protein source to replace fishmeal. Unfortunately, such by-products might affect shrimp acceptance of the offered feed. The present work evaluates the use of a chemosensory feed effector with attractive properties on the feeding behavior, growth performance, and salinity stress tolerance in juvenile Litopenaeus vannamei. Nine diets were formulated to contain either poultry meal (6%), or fishmeal (6% or 12%) as animal protein source, with feed effector supplemented at 0, 0.1, and 0.2%. The various diets were offered to naïve and non-naïve shrimp to evaluate feed consumption. Concurrently, shrimp feeding behavior was monitored using passive acoustic monitoring. Afterwards, a 42-days growth trial was performed followed by a salinity stress trial were performed to evaluate the effect of the feed effector in shrimp diets on animal growth, survival, and stress tolerance. Results of the present study indicate significant positive relationships between the number of clicks and feed consumed after 30 min (p < 0.001, r = 0.46 to 0.69). Additionally, shrimp offered the poultry meal-based diets produced significantly more “clicks” when the diets were supplemented with the feed effector, compared with the rest of the diets. However, the shrimp consumed poultry meal-based diets similarly to the fishmeal-based diets, only when supplemented with the feed effector. Interestingly, no significant differences were observed in terms of final biomass, final average individual weight, weight gain, FCR, or survival. However, salinity stress trial results indicate significantly better survival when offered diets supplemented with the feed effector, regardless of the level of inclusion. Results of the present work suggest that supplementing the feed effector to shrimp diets improves palatability and shrimp acceptance of diets formulated with poultry meal as sole animal protein source, as well as improves shrimp tolerance to salinity fluctuations. In an era of limited resources, supplementation of poultry meal-based shrimp diets with feed effector improves overall profitability by obtaining good shrimp growth with less expensive diets, and despite of stressors.

Effect of using a fat mixture to replace partial to total fish oil in diets for Litopenaeus vannamei

The present work aimed at evaluating if a mixture of different fat sources could replace fish oil in diets. Consequently, a mixture of poultry, palm kernel, and microalgae fat sources was blended (25, 71 and 4%) to replace fish oil at four different levels; 0 (Control), 25 (L-Mix), 50 (M-Mix), and 100% (H-Mix). Then, four different diets with defatted poultry by-product meal (PBM) and fish meal (FM), were used to formulate isoproteic and isolipidic diets. Juveniles of Litopenaeus vannamei (2.2 ± 0.3 g) were aleatorily distributed into 12 experimental units (500 L) in a recirculation system (RAS) with temperature controlled (28 °C) and constant aeration. After seven weeks of the experimental procedure, differences were found only in the survival rate and hepatosomatic index. The survival rate was 92% for M-Mix and H-Mix, while 70% was registered in the Control group. The hepatosomatic index was higher in the H-Mix (5.5) than in the rest of the dietary groups, with a minimum amount in the Control group (3.7). Even if no significant differences were found in the feed conversion ratio using an ANOVA (P = 0.5), a significant linear correlation revealed that a lower FCR (1.08) was registered in H-Mix compared to the Control (1.8). The fatty acid analysis demonstrated that those shorter than 14 carbons were efficiently utilized, as lauric acid (12:0) was observed lower in the hepatopancreas than in the supplied diets. In general, the rest of the fatty acids were used as reflected by their content of diets. On the contrary, the arachidonic acid (ARA) was efficiently accumulated in shrimps fed the three experimental diets despite its low concentration in the experimental treatments. In contrast, EPA and DHA were slightly lower than in the corresponding dietary treatments. It is concluded that the fat mixture containing poultry and palm kernel fats, with a DHA source from microalgae, resulted in a better survival rate and equal growth rate to shrimp reared with diets containing fish oil. Notwithstanding study results, it is recommended to research with higher amounts of medium-length fatty acids in diets together with attractants to increase feed ingestion.

Dietary sodium benzoate improves growth, morphology, antioxidant capacity and resistance against Aeromonas hydrophila of Pacific white shrimp (Litopenaeus vannamei)

Acidifier has become one of the most important substitutes for antibiotics, and its beneficial effects on growth performance and digestive ability have been evidenced. Sodium benzoate is a commonly used acidifier. A 56-day feeding test was carried out to elucidate the effects of dietary sodium benzoate on growth performance, morphology, antioxidant activity and intestinal microflora of juvenile Litopenaeus vannamei with an average initial body weight of 0.55 ± 0.01 g. Six experimental diets were prepared by adding 0, 750, 1000, 1250, 1500 and 1750 mg/kg sodium benzoate to the control diet. The results showed that: The final body weight (FBW) and weight gain (WG) of juvenile shrimp were significantly improved by diet supplemented with 1750 mg/kg sodium benzoate. Dietary 1750 mg/kg sodium benzoate significantly increased the trypsin activity. The activities of catalase (CAT), superoxide dismutase (SOD) and glutathione S-transferase (GST) in the intestine and hepatopancreas of the 1750 mg/kg sodium benzoate group were markedly higher than those of the control group. Furthermore, the expression levels of trypsin (TRY), amylase (AMS), lysozyme (LZM), interleukin-8 (IL8) and interleukin-10 (IL10) genes in the intestine significantly increased when the content of sodium benzoate in the diet was greater than or equal to 1000 mg/kg. The addition of 1500 and 1750 mg/kg sodium benzoate to the feed improved the intestinal and hepatopancreatic tissue structures of juvenile shrimp and enriched the diversity of intestinal microbiota. Sodium benzoate residues were not detected in each sodium benzoate supplemented group. At the end of the Aeromonas hydrophila challenge test, juvenile shrimp in the 1500 and 1750 mg/kg group exhibited significantly higher cumulative survival rates than that in the control group. Conclusively, dietary 1750 mg/kg sodium benzoate could improve the growth performance, antioxidant capacity, morphology, intestinal microflora and disease resistance of juvenile shrimp.

Evaluating the Antioxidant Properties of the Leaves and Stems of Alpinia oxyphylla In Vitro and Its Growth-Promoting, Muscle Composition Change, and Antioxidative Stress Function on Juvenile Litopenaeus vannamei.

Alpinia oxyphylla is a homology of medicine and food. This study aims to investigate the dominant chemical composition and explore the antioxidant properties of the ethanol extract of the leaves and stems of A. oxyphylla (AOE) on juvenile shrimp, Litopenaeus vannamei. An in vitro test showed that AOE and its dominant chemical composition procyanidin B-2 (1) and epicatechin (2) presented DPPH and ABTS radical scavenging activities. A shrimp feeding supplement experiment revealed that shrimp growth parameters and muscle composition were improved significantly when fed with a 200 mg/Kg AOE additive. Meanwhile, the activities of antioxidant enzymes (CAT, GSH-Px, SOD, and T-AOC) in serum and the liver and the expression of related genes (LvMn-SOD, LvCAT, LvproPo, and LvGSH-Px) were enhanced with various degrees in different AOE additive groups while the content of MDA was significantly decreased. Moreover, the antioxidative effect of AOE additive groups on shrimp was also observed in an acute ammonia nitrogen stress test.

Comparative study on the valorization of Sargassum from the Mexican Caribbean coast and Gulf of California as an ingredient on healthy diets for shrimp farming

Sargassum biomass is a potential ingredient for aquaculture formulations due to its high nutritional value and availability, as it contains a variety of essential nutrients including proteins, carbohydrates, lipids, vitamins, antioxidants, fiber, and minerals, which are essential for aquatic growing, development and health parameters including digestibility and immune response against diseases. Therefore, in this work, five experimental diets were formulated considering 2.5 % and 5 % levels of inclusion of Sargassum spp. from the Mexican Caribbean coasts (SC), and from the Gulf of California (SG), and one reference diet as a control. The characterization of the raw material and the proximal analysis of the five diets were evaluated according to standard reference methods. A 35-day feeding trial was conducted using juvenile Litopenaeus vannamei showed a shrimp survival rate of 97 ± 6 % (p > 0.05) on SC. Excellent weight gain (WG) performance of SC and SG diets at 2.5 % of inclusion resulted in >10 % WG compared to the control. The specific activity of amylase, lipase, trypsin, and chymotrypsin showed a significant increase by including Sargassum in diets, compared with the reference diet. Incorporating Sargassum at 2.5 % in feed formulations for shrimps showed a great opportunity to use it as an ingredient and improved production yields. The digestion and absorption parameters were represented by the enzymatic activity in which the diets based on Sargassum spp. from the Mexican Caribbean coast (SC) have resulted in the best performance.

Effects of Bacillus strain added as initial indigenous species into the biofloc system rearing Litopenaeus vannamei juveniles on biofloc preformation, water quality and shrimp growth

The effects of Bacillus strains added as initial indigenous species into the biofloc system rearing Litopenaeus vannamei juveniles on biofloc preformation, water quality and shrimp growth under low salinity conditions were investigated. Three biofloc systems were designed (control, NT9 treatment with the addition of Bacillus subtilis NT9, and YB3 treatment with the addition of B. cereus YB3) for a 7-day biofloc preformation experiment and a 63-day shrimp culture experiment. The results showed that at the end of the biofloc-preformation stage, the biofloc volume in the YB3 treatment (13.6 ± 6.1 mL L−1) and control (7.1 ± 3.6 mL L−1) were 8.0 and 4.2 times that in the NT9 treatment (1.7 ± 0.7 mL L−1), respectively. During the culture experiment, the effects of strain YB3 on dissolved oxygen and total bacterial counts were significant (P < 0.05). The specific growth rates of shrimp in the NT9 treatment (4.25 ± 0.06% d−1) and YB3 treatment (4.03 ± 0.32% d−1) were increased by 22.8% and 16.5%, respectively, compared with that in the control (3.46 ± 0.69% d−1). No shrimp mortality was observed in the NT9 treatment. In the YB3 treatment, the survival rate of shrimp was 66.7 ± 21.1%, which was lower than that in the control (81.5 ± 16.4%, P > 0.05). The highest and lowest productivity were found in the NT9 treatment (3.14 ± 0.10 kg m−3) and YB3 treatment (1.85 ± 0.62 kg m−3), respectively. The addition of different Bacillus strains as initial indigenous species to the biofloc system had different effects. B. cereus YB3 promoted biofloc formation, and B. subtilis NT9 elevated shrimp growth performance.

Toxic effects of glyphosate on histopathology and intestinal microflora of juvenile Litopenaeus vannamei

Glyphosate is a widely used broad-spectrum herbicide, its pollution to the surrounding conditions can't be ignored. It has been reported that glyphosate has poisonous impacts on aquatic animals. In this study, juvenile Litopenaeus vannamei (L. vannamei) was exposed to glyphosate, and the lethal concentration 50 (LC50) of glyphosate to juvenile L. vannamei for 48 h was 47.6 mg/L. The histological analysis for intestine and hepatopancreas and the intestinal microorganisms of L. vannamei were evaluated after 48 h of exposure to glyphosate with LC50. The histological analysis results showed that the lumen of hepatic tubules was diffused and deformed, the hepatic tubules were ruptured and intestinal villi were fallen off seriously after exposure to glyphosate for 48 h Moreover, the intestinal microbial composition and structure of L. vannamei were changed, with the abundance of Alphaproteobacteria increased significantly. The abundance of Rhodobacteraceae, Vibrio and Legionella increased, but there was no significant difference. The abundance of Bacillus, Paraburkholderia, Enhydrobacter, Comamonas and Alkanindiges decreased significantly. However, the homeostasis of intestinal microorganisms was destroyed. Phenotypic prediction of the two groups of microorganisms revealed a significant increase in the abundance of Facultatively Anaerobic in the glyphosate challenged group. This study suggested that hepatopancreas and intestinal tissue of L. vannamei were seriously damaged after 48 h of exposure to glyphosate with LC50, and intestinal microbial homeostasis was disrupted.

Dietary inclusion of roselle improves body colouration and survival of the whiteleg shrimp (Litopenaeus vannamei) juveniles challenged against Vibrio harveyi

This study was conducted to investigate the use of fresh and heat-treated roselle meals on growth, body colouration, and survival against Vibrio harveyi infection of whiteleg shrimp, Litopenaeus vannamei. Fresh (FR) or heat-treated roselle (HR) meals were added at 10% in isoproteic (38%) and isolipidic (7%) diets. A control diet was prepared without any addition of roselle meal. These diets were fed to shrimp (initial body weight 1.26g±0.02g) in triplicate groups for 8 weeks then challenged with V. harveyi. The growth, feed efficiency, total carotenoid content, and survival of shrimp and total Vibrio spp. counts in the hepatopancreas post-challenge test were estimated. No significant differences were recorded in the growth, survival, and feed utilization of the shrimp fed the roselle-added diets (FR or HR) compared to the control group. A significantly higher total carotenoid concentration was detected in shrimp fed with the FR and HR diets compared to the control (P&lt;0.05). The challenge test with V. harveyi showed that the shrimp specimens fed with FR and HR diets gained higher survival and a lower total number of Vibrio spp. count in the hepatopancreas compared to the control group. The present finding suggests that fresh or heat-treated roselle meals provide a good source of carotenoid and increase the resistance of shrimp against vibriosis without affecting the growth and feed utilization.

Dietary Use of Methionine Sources and Bacillus amyloliquefaciens CECT 5940 Influences Growth Performance, Hepatopancreatic Histology, Digestion, Immunity, and Digestive Microbiota of Litopenaeus vannamei Fed Reduced Fishmeal Diets.

An 8-week feeding trial investigated the effect of Fishmeal (FM) replacement by soybean meal (SBM) and poultry by-product meal (PBM) in diets supplemented with DL-Met, MET-MET (AQUAVI®), Bacillus amyloliquefaciens CECT 5940 (ECOBIOL®) and their combinations on growth performance and health of juvenile Litopenaeus vannamei. A total of six experimental diets were formulated according to L. vannamei nutritional requirements. A total of 480 shrimp (0.30 ± 0.04 g) were randomly distributed into 24 tanks (4 repetitions/each diet, 20 shrimp/tank). Shrimp were fed with control diet (CD; 200 g/Kg fishmeal) and five diets with 50% FM replacement supplemented with different methionine sources, probiotic (B. amyloliquefaciens CECT 5940) and their combinations: D1 (0.13% DL-MET), D2 (0.06% MET-MET), D3 (0.19% MET-MET), D4 (0.13% DL-MET plus 0.10% B. amyloliquefaciens CECT 5940 and D5 (0.06% MET-MET plus 0.10% B. amyloliquefaciens CECT 5940). Shrimp fed D3 and D5 had significantly higher final, weekly weight gain, and final biomass compared to shrimp fed CD (p < 0.05). Shrimp fed D2 to D5 increased the hepatopancreas epithelial cell height (p < 0.05). Digestive enzymatic activities were significantly increased in shrimp hepatopancreas’ fed D3 (p < 0.05). Meanwhile, shrimp fed D1 had significant downregulation of immune-related genes (p < 0.05). Moreover, shrimp fed D3 and D5 increased the abundance of beneficial prokaryotic microorganisms such as Pseudoalteromonas and Demequina related to carbohydrate metabolism and immune stimulation. Also, shrimp fed D3 and D5 increased the abundance of beneficial eukaryotic microorganism as Aurantiochytrium and Aplanochytrium were related to eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) production which plays a role in growth promoting or boosting the immunity of aquatic organisms. Therefore, fishmeal could be partially substituted up to 50% by SBM and PBM in diets supplemented with 0.19% MET-MET (AQUAVI®) or 0.06% MET-MET (AQUAVI®) plus 0.10% B. amyloliquefaciens CECT 5940 (ECOBIOL®) and improve the productive performance, health, and immunity of white shrimp. Further research is necessary to investigate synergistic effects of amino acids and probiotics in farmed shrimp diets, as well as to evaluate how SBM and PBM influence the fatty acid composition of reduced fishmeal diets and shrimp muscle quality. Nevertheless, this information could be interesting to develop low fishmeal feeds for aquaculture without affecting the growth and welfare of aquatic organisms.

Optimal Levels of Fish Meal and Methionine in Diets for Juvenile Litopenaeus vannamei to Support Maximum Growth Performance with Economic Efficiency.

This work investigated the optimal levels of fish meal (FML) and dietary methionine (Met) required for maximum growth performance of juvenile Litopenaeus vannamei with economic efficiency. Four sets of diets were prepared to contain 0.00, 6.00, 12.00 and 18.00% FML. Each set was supplemented with DL-methionyl-DL-methionine (DL-Met-Met) to result in a total dietary Met (Met + Cys) content of 0.58 (1.05), 0.69 (1.16), and 0.82% (1.29%), on a fed basis. Shrimp of 1.00 ± 0.08 g were stocked in 60 outdoor tanks of 1 m3 with 100 shrimp/m2, allowing five replications per dietary group. Shrimp in all the groups were fed 10 times daily for 70 days. In a subsequent trial, dietary protein and amino acid digestibility of four FML groups, but only at high dietary Met levels (~0.82%), were evaluated in 40 60 L indoor tanks (11 replicates per diet) for 93 days with 70 shrimp/m2. Final shrimp survival (92.85 ± 4.82%, mean ± standard deviation), weekly weight gain (1.17 ± 0.08 g), apparent feed intake (13.3 ± 0.5 g of feed per stocked shrimp), and feed conversion ratio (1.18 ± 0.06) were unaffected by dietary FML level and Met content. Gained yield was adversely affected when FML was reduced from 18 and 12% (1156 and 1167 g/m2, respectively) to 0 (1090 g/m2), but no change was observed at 6% (1121 g/m2). A significant interaction was detected between FML level and dietary Met. Under 0 and 6% FML conditions, higher levels of total dietary Met, 0.69 and 0.82%, respectively, were required to maximize shrimp BW. In comparison, at 12 and 18% FML, a dietary Met content of only 0.58% was sufficient. Overall, results indicated the use of FML can be minimized or completely eliminated without major detrimental effects on feed digestibility or shrimp growth performance, as long as proper supplementation of Met is carried out. Diets with 0 FML or with only 6% delivered the highest profit and return on investment compared to diets with higher levels.

Silver nano/microparticle toxicity in the shrimp Litopenaeus vannamei (Boone, 1931)

The effects of silver nano/microparticles (AgP) on juvenile Litopenaeus vannamei shrimp were evaluated through several responses, aiming to use it as a prophylactic and therapeutic method. Shrimps (3.19 ± 0.13 g) were exposed to clear water for 3 h with increasing concentrations of nanosilver (0; 25; 100; and 400 μg/l). After 3 h of exposure, they were transferred to water without nanosilver for 30 days (recovery). The weight gain and weekly growth were not affected by AgNP. Total antioxidant capacity (ACAP) increased in the hepatopancreas (exposure period) and gills (recovery) in shrimp exposed to AgNP. In muscle, ACAP was induced in shrimp exposed to 100 μg/l AgNP (exposure). In the gills, there was an increase in TBARS in shrimp exposed to 100 μg/l AgNP (recovery). In the concentration of protein-associated sulfhydryl groups (P-SH), a decrease was observed in the hepatopancreas (recovery) in the 100 μg/l AgNP treatment. In chromaticity parameters, an increase in reddish tones was observed in shrimp exposed to 100 μg/l AgNP (recovery). An increase in granular hemocytes was verified in shrimp exposed to 25 and 400 μg/l AgNP during exposure. Tissues analyzed histologically showed normal patterns without apoptosis or necrosis processes, and after 30 d of recovery, only in one muscle sample of shrimp exposed to μg/l of AgNP was silver detected. It is concluded that a prophylactic action of short duration (3 h) mostly did not affected the welfare of shrimp L. vannamei and can be considered its use as a therapeutic strategy.

Dietary contribution of fermented grain pellets to the growth of juvenile Litopenaeus vannamei raised in an intensive biofloc-based rearing system

Dietary contribution of fermented grain pellets to the growth of juvenile Litopenaeus vannamei raised in an intensive biofloc-based rearing system

Effects of Bacillus subtilis DSM 32315 (Gutcare®) on the growth performance, antioxidant status, immune ability and intestinal function for juvenile Litopenaeus vannamei fed with high/low-fishmeal diets

This study was conducted to investigate the effects of dietary Bacillus subtilis DSM 32315 (Gutcare®) supplementation on the growth performance, antioxidant status, immune ability and intestinal function in juvenile Litopenaeus vannamei fed with high/low-fishmeal diets. A 4 × 2 two-factor design was formulated with graded dietary Gutcare® and fishmeal levels. Specifically, four Gutcare® supplemental levels (0, 0.05%, 0.15% and 0.3%) were added under two fishmeal diets (20% and 5% fishmeal levels). Each diet was randomly assigned to five replicate groups of 30 juvenile Pacific white shrimp that were stocked in fiberglass tanks. The results indicated no significant inhabitation on the growth performance, hepatopancreas antioxidant capacity, immune response and intestinal function at 5% fishmeal compared with 20% fishmeal. Shrimp fed with Gutcare® supplementation regardless of high/low-fishmeal diets exhibited higher growth performance, antioxidant- and immune-related enzyme activities (P < 0.05) compared with that 0% Gutcare® supplementation. However, none of the treatments found significant differences in feed efficiency and survival. The mRNA expression levels of Cu/Zn superoxide dismutase, heat shock protein 70, glutathione peroxidase, prophenoloxidase and lysozyme were significantly up-regulated (P < 0.05) at shrimp fed with Gutcare®. Moreover, the results of mid-intestine morphology showed a significant increase with the addition of Gutcare®, and the highest height and thickness of intestinal epithelium occurred at shrimp fed 0.15% Gutcare®. Bacterial community composition showed that shrimp fed with the graded Gutcare® significantly increased the abundance of Firmicute and reduced the relative abundance of Vibrio (P < 0.05). In conclusion, 5% fishmeal supplementation with well-balanced amino acid composition had no adverse effect on the growth performance of L. vannamei when compared with the 20% fishmeal. Dietary Gutcare® significantly enhanced immunity and antioxidant capacity, and improved intestinal function of L. vannamei. The positive effect of Gutcare® at 5% fishmeal diet provided a possibility for reducing fish meal in the commercial diets of Pacific white shrimp.

Dietary lysine requirement of juvenile Pacific white shrimp, Litopenaeus vannamei (Boone, 1931) reared in inland saline water of 10 ppt salinity

A feeding trial of 60 days was conducted to assess the dietary lysine requirement of juvenile Litopenaeus vannamei reared in inland saline water. Seven isonitrogenous (~ 360 g crude protein/kg feed), isolipidic (~ 60 g crude lipid/kg feed) and isocaloric (~ 18 MJ gross energy/kg feed) semi-purified test diets with graded lysine levels viz., 13.7 (L1), 16.3 (L2), 18.7 (L3), 21.4 (L4), 23.8 (L5), 26.3 (L6) and 28.9 g/kg (L7) were formulated and prepared. Three hundred and seventy-eight L. vannamei juveniles (2.75 ± 0.01 g) were randomly distributed (60 no/m3 or 33 no/m2) into seven test groups in triplicates following a completely randomized design. L. vannamei juveniles were fed to the apparent satiation level four times daily. At the end of the feeding trial, the results indicated that dietary lysine levels have significantly (P < 0.05) affected the growth and nutrient utilization parameters in juvenile L. vannamei. An increase (P < 0.05) in final body weight, weight gain percentage (WG%), thermal growth coefficient (TGC), protein efficiency ratio and protein productive value were observed with the increasing dietary lysine levels from 13.7 to 23.8 g/kg after which a decreasing trend was observed. The relative feed intake and feed conversion ratio showed a decreasing trend from lower dietary lysine levels to higher levels. Survival rates of experimented shrimp were not significantly different (P > 0.05) among the treatment groups. The whole body crude protein and crude lipid content of L. vannamei showed significantly (P < 0.05) increasing and decreasing trends, respectively towards the increasing dietary lysine levels. The hepatopancreatic and muscle protein metabolic enzyme activities, haemocyanin and serum total protein content of L. vannamei varied significantly among the treatment groups. The broken-line linear and second-order polynomial regression analysis of WG% and TGC against the dietary lysine levels indicated that the optimal dietary lysine level with confidence interval (CI) for juvenile L. vannamei reared in inland saline water of 10 ppt salinity is 23.46 (22.59–24.88 g/kg, 95% CI) to 25.24 g/kg (24.27–26.53 g/kg, 95% CI) and 23.26 (22.70–24.15 g/kg, 95% CI) to 25.25 g/kg (24.27–26.53 g/kg, 95% CI) of the diet, respectively.

Evaluation of short-term toxicity of ammonia and nitrite on the survival of whiteleg shrimp, Litopenaeus vannamei juveniles

The effects of short-term toxicity of total ammonia nitrogen (TAN) and nitrite were estimated in juveniles of Litopenaeus vannamei under laboratory conditions. In the first experiment, L. vannamei juveniles were exposed to different concentrations of ammonia (0, 5, 10, 15, 20, 30, and 40 mg of TAN L-1) or nitrite (0, 5, 10, 20, 30, 40, and 50 mg of NO2–N L-1), using the static renewal method at a salinity of 20 ppt and pH 8.2. The survival rates of juveniles significantly decreased when exposed to increased concentrations of ammonia or nitrite during the 96 h bioassays. The 24, 48, 72, and 96 h LC50 values of TAN in juveniles were 45.5, 30.1, 13.8, and 6.3 mg L-1, respectively, while the LC50 values of NO2–N at 24, 48, 72, and 96 h were 37.6, 16.7, 8.8, and 4.8 mg L-1, respectively. Experiment 2 evaluated the tolerance of L. vannamei juveniles at various salinities (5, 10, 15, and 20 ppt) under a high concentration of ammonia or nitrite (5 mg L-1). Results showed that the survival rates of L. vannamei at 5 ppt and 10 ppt were significantly lower than those at 20 ppt after 72 h and 96 h of exposure.

The Optimization of Dietary Protein Level and Carbon Sources on Biofloc Nutritive Values, Bacterial Abundance, and Growth Performances of Whiteleg Shrimp (Litopenaeusvannamei) Juveniles.

A biofloc technology-based 75-day indoor growth trial in an 80 L glass aquaria was conducted to evaluate the effects of two different carbon sources (sugarcane bagasse, SB, and wheat flour, WF) on the biofloc composition, bacterial abundance, and growth of whiteleg shrimp (Litopenaeus vannamei) juveniles (0.23 ± 0.04 g). Three different levels of dietary protein content (250, 300, and 350 g protein kg−1 diet) and two carbon sources (SB and WF) were applied (SB250, WF250, SB300, WF300, SB350, and WF350, respectively), comparing to a controlled diet without biofloc and fed on a 450 g protein kg−1 diet (C450). With the addition of SB and WF, water quality was in the ideal recommended ranges for L. vannamei culture. At the end of the experiment, the biofloc volume increased with increasing dietary protein levels. The nutritional value of biofloc in different treatments was influenced by dietary protein and added SB and WF. Increasing dietary protein significantly increased the protein and lipid contents of the produced biofloc. The use of WF as a carbon source significantly increased lipids and nitrogen-free extract in the biofloc. The total heterotrophic bacterial (THB) count was significantly higher (p < 0.05) in WF300 and WF350 than in the other treatments. The mean effect of the protein levels and carbon source was significantly reported, whereas the highest significant THB count was recorded with 300 dietary protein and using WF as a carbon source. The growth performances of L. vannamei fed with biofloc treatments were significantly (p < 0.05) higher than the C450 group. The highest final weight and weight gain were recorded in SB350 treatment. The feed conversion ratio was not affected by reducing dietary protein levels; meanwhile, the protein efficiency ratio increased significantly in biofloc treatments than in the control. Overall, the results demonstrate that, compared to the control treatment of 450 dietary protein, the biofloc treatments using WF as a carbon source could compensate for the reduction in the dietary protein levels in the diet of L. vannamei and maintain higher zootechnical performance.

Pseudomonas oligotrophica sp. nov., a Novel Denitrifying Bacterium Possessing Nitrogen Removal Capability Under Low Carbon-Nitrogen Ratio Condition.

Pseudomonas is a large and diverse genus within the Gammaproteobacteria known for its important ecological role in the environment. These bacteria exhibit versatile features of which the ability of heterotrophic nitrification and aerobic denitrification can be applied for nitrogen removal from the wastewater. A novel denitrifying bacterium, designated JM10B5aT, was isolated from the pond water for juvenile Litopenaeus vannamei. The phylogenetic, genomic, physiological, and biochemical analyses illustrated that strain JM10B5aT represented a novel species of the genus Pseudomonas, for which the name Pseudomonas oligotrophica sp. nov. was proposed. The effects of carbon sources and C/N ratios on denitrification performance of strain JM10B5aT were investigated. In addition, the results revealed that sodium acetate was selected as the optimum carbon source for denitrification of this strain. Besides, strain JM10B5aT could exhibit complete nitrate removal at the low C/N ratio of 3. Genomic analyses revealed that JM10B5aT possessed the functional genes including napA, narG, nirS, norB, and nosZ, which might participate in the complete denitrification process. Comparative genomic analyses indicated that many genes related to aggregation, utilization of alkylphosphonate and tricarballylate, biosynthesis of cofactors, and vitamins were contained in the genome of strain JM10B5aT. These genomic features were indicative of its adaption to various niches. Moreover, strain JM10B5aT harbored the complete operons required for the biosynthesis of vibrioferrin, a siderophore, which might be conducive to the high denitrification efficiency of denitrifying bacterium at low C/N ratio. Our findings demonstrated that the strain JM10B5aT could be a promising candidate for treating wastewater with a low C/N ratio.

Dietary surface-modified zirconium silicate nanoparticles enhance immune response, antioxidant activity and cytokine genes expression of the white shrimp Litopenaeus vannamei against Vibrio harveyi

This experiment was conducted to evaluate the effects of surface-modified ZrSiO4 nanoparticles on non-specific immunity, antioxidant activity, cytokines gene expression and mortality of the shrimp Litopenaeus vannamei juveniles challenged with Vibrio harveyi. Four diets were prepared to be supplemented with ZrSiO4 NPs-SDS as follows: 0, 20, 40 or 60 mg Kg‐−1 diet. These ZrSiO4 NPs-SDS supplemented diets were fed to L. vannamei juveniles (2.5 ± 0.5 g) for 50 days. The results revealed that ZrSiO4 NPs-SDS significantly increased phagocytosis, respiratory burst, lysozyme activity and alternative complement activity of L. vannamei compared with the control. The results also indicated that dietary ZrSiO4 NPs-SDS significantly improved superoxide dismutase, phenoloxidase, glutathione peroxidase activities and reduced malondialdehyde of L. vannamei compared with the control. All shrimp groups fed ZrSiO4 NPs-SDS exhibited significant up-regulation in the immune related genes (IL-1β, IL-8, IL-10, TNF-α and IFN-γ). Moreover, the supplementation of dietary ZrSiO4 NPs-SDS significantly reduced alanine aminotransferase, aspartate aminotransferase and mortality of L. vannamei. Thus, the inclusion of ZrSiO4 NPs-SDS in the diet improved non-specific immunity, antioxidant activity and hepatic functions of L. vannamei juveniles and enhanced their resistance to V. harveyi. The recommended level of ZrSiO4 NPs-SDS is 40 mg Kg−1 diet.

A Newly Isolated Strain of Haematococcus pluvialis GXU-A23 Improves the Growth Performance, Antioxidant and Anti-Inflammatory Status, Metabolic Capacity and Mid-intestine Morphology of Juvenile Litopenaeus vannamei.

Haematococcus pluvialis can be used as a green additive in aquafeeds due to it contains rich astaxanthin and polyunsaturated fatty acid. In the present study, a newly strain of H. pluvialis GXU-A23 with high concentration of astaxanthin was firstly isolated by a newly culture strategy in our laboratory. In addition, H. pluvialis GXU-A23 was applied in the Litopenaeus vannamei feed for determining whether it has positive effects on the growth performance, antioxidant and anti-inflammatory status, metabolic capacity and mid-intestine morphology of juvenile L. vannamei. Shrimp with 0.63 g approximately initial body weight were fed diets supplemented with/without 50 g/kg H. pluvialis GXU-A23. After 8 weeks feeding intervention, significantly higher growth performance of L. vannamei was obtained in the H. pluvialis GXU-A23 treatment group compared to the control group (p < 0.05). At the same time, L. vannamei fed with H. pluvialis GXU-A23 acquired significantly better antioxidant and anti-inflammatory status than the control group (p < 0.05). In addition, higher RNA expression level of hepatopancreas digestive enzyme, hepatopancreas lipid and glucose metabolic enzymes as well as better mid-intestine morphology were found in the H. pluvialis GXU-A23 treatment group than the control group (p < 0.05). These results indicated that 50 g/kg H. pluvialis GXU-A23 was suitable for the L. vannamei feed, which could improve the growth performance, antioxidant and anti-inflammatory status, metabolic capacity and mid-intestine morphology of juvenile L. vannamei.

Data Mining Techniques: New Method to Identify the Effects of Aquaculture Binder with Sardine on Diets of Juvenile Litopenaeus vannamei

In this research, a dataset of growth performances and nutritional composition of juvenile Litopenaeus vannamei after being fed two diets that include aquaculture binder with sardine for 7 weeks was analyzed using data mining techniques: the K-Means Clustering Algorithm and PCA Biplot, to have a visualization of each parameter (vector) measured. The parameters evaluated were: weight gain, specific growth rate, feed efficiency, protein efficiency ratio, survival percent, moisture content, crude protein, crude lipid, and ash content. Data mining tools showed the juvenile Litopenaeus vannamei fed with mixture 2 (pellets mixed with the binder of sardine subproducts) presented the highest growth performances and nutritional composition, 23 juvenile L. vannamei shrimps showed higher relation with crude protein and crude lipid, 30 L. vannamei shrimps presented higher relation with ash, and 37 juvenile L. vannamei shrimps showed higher relation with ash and moisture. The results obtained in experimental procedures indicate that the use of a binder of sardine subproducts in shrimp diets improves the commercial parameters, improving the aquaculture field.