Pacific White Shrimp Penaeus Vannamei Research Articles

Effect of feed restriction for Pacific white shrimp Penaeus vannamei in a semi-intensive synbiotic system: Plankton community, growth and economics

The aim of this study was to evaluate the effects of feed restriction on the plankton community, growth and economic variables of Penaeus vannamei culture in a synbiotic system. Two treatments were used: partial feed restriction (FR) and control without restriction (WR). The study was conducted in triplicate using a completely randomized design. The juveniles (1.67 g ± 0.15) were transferred to six lined ponds of 600 m2 (12 shrimp m−2 density, 20 ppt salinity) for 60 days and fed with commercial feed (35% CP). The ponds received organic (synbiotic — rice bran) and inorganic (urea) fertilization. Shrimp zootechnical performance indicated significant difference in feed conversion ratio (FCR), with values of 0.30 and 0.59 in FR and WR, respectively, which shows a reduction of 49.3%. Plankton showed no significant difference, with dominance of Chlorophyta and Protozoan. In the economic analysis, there was only different amount of feed between the treatments, it implied significant differences reducing the effective operating costs by 21.8% and total operating costs by 20.2% in the FR treatment. In addition, FR break-even point was also reduced by 18.8%, however both treatments had equally positive profitability indicators. Therefore, the feed restriction for P. vannamei in synbiotic system at low stocking density is possible, seeing that the shrimp presented total compensatory growth, reducing FCR without altering the other zootechnical performance parameters. It contributed to costs reduction, although it is important to highlight that offering feed in full cycle with low FCR can promote greater returns to the producer (∼ 40%). Hence, feed restriction is recommended, especially in shrimp farms with low working capital.

A Negative Regulatory Feedback Loop within the JAK-STAT Pathway Mediated by the Protein Tyrosine Phosphatase DUSP14 in Shrimp.

The JAK-STAT pathway is a central communication node for various biological processes. Its activation is characterized by phosphorylation and nuclear translocation of the transcription factor STAT. The regulatory balance of JAK-STAT signaling is important for maintenance of immune homeostasis. Protein tyrosine phosphatases (PTPs) induce dephosphorylation of tyrosine residues in intracellular proteins and generally function as negative regulators in cell signaling. However, the roles of PTPs in JAK-STAT signaling, especially in invertebrates, remain largely unknown. Pacific white shrimp Penaeus vannamei is currently an important model for studying invertebrate immunity. This study identified a novel member of the dual-specificity phosphatase (DUSP) subclass of the PTP superfamily in P. vannamei, named PvDUSP14. By interacting with and dephosphorylating STAT, PvDUSP14 inhibits the excessive activation of the JAK-STAT pathway, and silencing of PvDUSP14 significantly enhances humoral and cellular immunity in shrimp. The promoter of PvDUSP14 contains a STAT-binding motif and can be directly activated by STAT, suggesting that PvDUSP14 is a regulatory target gene of the JAK-STAT pathway and mediates a negative feedback regulatory loop. This feedback loop plays a role in maintaining homeostasis of JAK-STAT signaling and is involved in antibacterial and antiviral immune responses in shrimp. Therefore, the current study revealed a novel inhibitory mechanism of JAK-STAT signaling, which is of significance for studying the regulatory mechanisms of immune homeostasis in invertebrates.

Aurantiochytrium sp. and Nannochloropsis spp. meals as substitutes for fish oil in practical diets for Pacific white shrimp Penaeus vannamei

This study aimed to evaluate the use of microalgae meal (Aurantiochytrium sp. and Nannochloropsis spp.) as a substitute for fish oil in the diet of shrimp Penaeus vannamei reared in a clear water system. In the diet of these animals, the concentration of fish oil decreased as microalgae meal was inserted, and these were used in five different substitutions: 0, 25, 50, 75, and 100%. The treatments were carried out in triplicate, and after 49 days of cultivation, the zootechnical parameters and the composition of fatty acids in the animals' muscles were analyzed. In zootechnical performance, the shrimp obtained an average final weight of 16.59 ± 0.3 g, and the growth was approximately 1.89 ± 0.30 g week-1. In addition, feed conversion was, on average, 1.47 ± 0.28, and survival was greater than 97%. However, no significant difference was observed in these parameters. Regardless of the levels of fish oil replacement by microalgae meal, the composition of fatty acids in the shrimp muscle was ensured, as well as their quantity within groups, such as n-3 and n-6 polyunsaturated fatty acids. Thus, with the results obtained in the present study, it is suggested that it is possible to formulate a high-performance diet without any ingredients of marine origin (fish oil or fish meal), contributing to aquaculture's sustainability.

Metabolic and immune status of Pacific white shrimp Penaeus vannamei concerning farming conditions

Biomarkers for monitoring shrimp health have been proposed but scarcely evaluated at the farm level. We analyzed several indicators of energy status in shrimp under farming conditions concerning stocking densities (100 m-2 with biofloc, 15 and 7 m-2). The influence of the year's season (temperature) was also analyzed, and, finally, an unfortunate event of White spot syndrome virus (WSSV) infection occurred on the 7 m-2 farms, adding another condition. At shrimp sampling from ponds, the effect of acute handling stress was also analyzed for indicators typically affected by such procedure with a 3- and 10-fold increase in glucose and lactate levels in hemolymph, respectively, regardless of density. This response was partially blunted at lower temperatures and WSSV incidence. Increased levels of protein in the hepatopancreas, adenylic energy charge (AEC) in both hepatopancreas and muscle and phosphagens in muscle were observed in shrimp from the 100 m-2 farms, suggesting a better nutritional and energetic status in shrimp cultured at high density with biofloc technology. Shrimp with WSSV presented lower hemocyanin levels in hemolymph, most likely associated with its role in the immune response. In WSSV-infected shrimp, the stress response regarding glucose increase was blunted, whereas a stress-induced increase in triglycerides (TG) levels in hemolymph was observed only with WSSV. Increased TG levels in those shrimp hepatopancreas could indicate a switch from carbohydrate to lipid-based metabolism associated with the preferential use of carbohydrates (Warburg effect) for virus replication in the early infection state.

Mysid meal as a dietary replacement for fishmeal in the diets of Pacific white shrimp Penaeus vannamei (Boone, 1931) postlarvae

The current study evaluates the nutritional and feed value of mysid meal (MM) as a substitute for fishmeal (FM) in the Pacific white shrimp (Penaeus vannamei) postlarvae diet. Five experimental diets were formulated by replacing 0 (MM0), 25 (MM25), 50 (MM50), 75 (MM75), and 100 % (MM100) of dietary FM with MM. These experimental feeds were fed to P. vannamei postlarvae in a 60-day feeding trial. Results revealed that MM could entirely substitute 100 % FM in the white shrimp diet. Furthermore, results showed that 75 % FM replacement with MM elicited a growth-enhancing effect and improved feed nutrient utilization. No significant treatment effects were detected in the survival, total feed intake, and biochemical body composition of P. vannamei. The observed improvement in shrimp growth in terms of weight gain (WG), specific growth rate (SGR), and nutrient retention were positively correlated with the substitution level of FM by MM. The feed conversion ratio (FCR) was negatively correlated with the substitution of MM and with the growth indices including WG and SGR. In conclusion, 100% of the FM (40% in the control diet) can be substituted by dietary MM without affecting the survival, growth, feed utilization, and biochemical carcass composition of P. vannamei. Polynomial regression analysis of SGR indicates that 65.50% of MM is optimum to replace FM in the diet of P. vannamei to attain maximum growth.

Draft genome sequence of Bacillus velezensis strain 3TSA-3, a potential probiotic for Pacific white shrimp Penaeus vannamei postlarvae isolated from commercial hatchery tanks.

We report the draft genome of Bacillus velezensis strain 3TSA-3, isolated from Pacific white shrimp Penaeus vannamei postlarvae collected from a hatchery tank with high survival despite the presence of pathogenic Vibrio. The strain possesses genes encoding bacteriocins and lacks virulence factor genes, characteristics for a potential aquaculture probiotic.

Dinotefuran exposure alters biochemical, metabolomic, gut microbiome, and growth responses in decapoda pacific white shrimp Penaeus vannamei

Dinotefuran, a neonicotinoid insecticide, may impact nontarget organisms such as Decapoda P. vannamei shrimp with nervous systems similar to insects. Exposing shrimp to low dinotefuran concentrations (6, 60, and 600 μg/L) for 21 days affected growth, hepatosomatic index, and survival. Biomarkers erythromycin-N-demethylase, alanine aminotransferase, and catalase increased in all exposed groups, while glutathione S-transferase is the opposite; aminopyrin-N-demethylase, malondialdehyde, and aspartate aminotransferase increased at 60 and 600 μg/L. Concentration-dependent effects on gut microbiota altered the abundance of bacterial groups, increased potentially pathogenic and oxidative stress-resistant phenotypes, and decreased biofilm formation. Gram-positive/negative microbiota changed significantly. Metabolite differences between the exposed and control groups were identified using mass spectrometry and KEGG pathway enrichment. N-acetylcystathionine showed potential as a reliable dinotefuran metabolic marker. Weighted correlation network analysis (WGCNA) results indicated high connectivity of cruecdysone in the metabolite network and significant enrichment at 600 μg/L dinotefuran. The WGCNA results revealed a highly significant negative correlation between two key metabolites, caldine and indican, and the gut microbiota within co-expression modules. Overall, the risk of dinotefuran exposure to non-target organisms in aquatic environments still requires further attention.

Different Protein Hydrolysates Can Be Used in the Penaeus vannamei (Boone, 1934) Diet as a Partial Replacement for Fish Meal during the Grow-Out Phase

This study evaluated the inclusion of protein hydrolysates and a commercial product as a partial replacement for fish meals in the diet of Pacific white shrimp (Penaeus vannamei) during the grow-out phase. A recirculation system with 24 experimental units and a biological filter was used. The experimental design was completely randomized with six treatments: control; chicken protein hydrolysate (CPH); enzymatic hydrolysate of chicken feathers; Aquabite®; CPH + maltodextrin; CPH + yeast; and four replicates. After 50 days, the zootechnical performance and animal welfare parameters, centesimal carcass composition, digestive enzyme activity, and hemocyte count were evaluated. The treatments did not affect the zootechnical performance and total hemocyte count of the animals (p > 0.05). The evaluation of the antenna length indicated that all animals were in good health. The antenna length in treatment T5 was significantly greater (p > 0.05) than that in T4 and similar to that in treatments T3 and T6, demonstrating a positive influence of dietary protein hydrolysates. Concerning animal welfare, dietary protein hydrolysates influenced the length of the antenna (p < 0.05). The antenna length associated with different treatments indicated that the animals were in good welfare conditions in the production environment. With respect to body chemical composition, dry matter, ether extract, and ash were affected by the treatments (p < 0.05). Regarding the analysis of digestive enzymes, the treatments influenced the activities of amylase and trypsin (p < 0.05). The performance of the animals was satisfactory under all treatments, including enzymatic activity, demonstrating the possibility of using hydrolysates.

Effects of Cold Stress on the Hemolymph of the Pacific White Shrimp Penaeus vannamei

Temperature is an important factor in the physiological processes of aquatic organisms and can seriously affect several chemical and biological processes in their bodies, including respiratory metabolism, antioxidant capacity, immune capacity, and signal transduction. In this study, physiological, transcriptomic, and metabolomic analyses were used to investigate the response of Penaeus vannamei to cold stress. The results indicated that cold stress disrupted nucleotide metabolism and inhibited gluconeogenesis. However, shrimp exhibited response mechanisms in order to enhance cold tolerance, regulating changes in key genes and metabolites in amino acid and lipid metabolism to increase energy supply and protect cell membrane stability. In addition, the response included regulating Ca2+ pumps and ion channels to maintain intracellular ion homeostasis and osmotic balance. When the temperature dropped further, oxidative damage occurred due to overwhelming of the antioxidant defense system, and immune function was inhibited. This research provides some references regarding the molecular mechanisms involved in responding to cold stress and potential strategies to improve cold tolerance in P. vannamei; these are important references for studying the cold stress response of shrimp.

The influence of biofloc system on Vibrio composition, the growth and the gut microvilli performance of the Pacific white shrimp Penaeus vannamei

Biofloc technology has been shown to have a positive impact on shrimp culture by controlling pathogenic Vibrio. This study aimed to analyze the effect of biofloc on the Vibrio composition in water and shrimp gut, as well as the growth performance and microvilli of Pacific white shrimp (Penaeus vannamei). Shrimp post-larvae measuring 0.66 ± 0.02 g were reared in a glass aquarium (working volume 22 L) of 6 units with a density of 150 shrimp m-3 for 28 days. The treatments included rearing in the biofloc system with C/N ratio 10, and without a biofloc system as a control. The results showed that Vibrio was highly prevalent in the control gut (4.13%) and biofloc water (3.77%), but only a few were found in the control water (0.16%) and biofloc-treated gut (0.11%). V. hepatarius (1.10%) and V. nereis (1.06%) were found to dominate the Vibrio bacterial community in the biofloc system maintenance media, while Vibrio sp. Hep-1b-8 (2.26%) and V. parahaemolyticus (0.80%) known as a pathogenic bacteria dominated the control shrimp gut. The biofloc system significantly increased the digestive enzyme activity, growth performance, and microvilli length in the shrimp gut. In conclusion, the application of a biofloc system in shrimp culture can affect the composition and abundance of bacterial communities in both the culture environment and the shrimp gut, and improve growth performance with higher digestive enzyme activity and longer microvilli in the gut.
 
 Keywords: biocontrol, biofloc, microbiota, shrimp, Vibrio
 
 ABSTRAK
 
 Teknologi bioflok menunjukkan dampak positif pada kegiatan budidaya udang vaname dengan mengendalikan bakteri patogen salah satunya Vibrio. Penelitian ini bertujuan untuk menganalisis efek bioflok terhadap komposisi Vibrio pada air dan usus udang, serta kinerja pertumbuhan dan mikrovili udang vaname (Penaeus vanamei). Udang post-larva berukuran 0.66 ± 0.02 g dipelihara pada akuarium kaca (volume air 22 L) sebanyak 6 unit dengan kepadatan 150 ekor m-3 selama 28 hari. Perlakuan meliputi pemeliharaan udang pada sistem bioflok dengan rasio C/N 10, dan tanpa sistem bioflok sebagai perlakuan kontrol. Hasil pengamatan menunjukkan kelimpahan Vibrio yang cukup tinggi pada usus perlakuan kontrol (4.13%) dan air perlakuan bioflok (3.77%), tetapi sangat sedikit ditemukan pada air perlakuan kontrol dan usus perlakuan bioflok. Selanjutnya, V. hepatarius (2.26%) dan V. nereis (1.06%) terdeteksi mendominasi komunitas bakteri Vibrio di media pemeliharaan pada sistem bioflok, sedangkan Vibrio sp. Hep-1b-8 (2.26%) dan V. parahaemolyticus (0.80%) mendominasi usus udang vaname pada perlakuan kontrol. Sistem bioflok juga mampu meningkatkan aktivitas enzim pencernaan, performa pertumbuhan, dan panjang mikrovili usus secara signifikan (P < 0.05). Kesimpulan dari penelitian ini adalah penerapan sistem bioflok pada budidaya udang vaname mampu memengaruhi komposisi dan kelimpahan komunitas bakteri Vibrio pada lingkungan budidaya maupun pada usus udang, serta meningkatkan performa pertumbuhan dengan aktivitas enzim pencernaan yang lebih baik dan mikrovilli usus yang lebih panjang.
 
 Kata kunci: bioflok, biokontrol, microbiota, udang vaname, Vibrio

Preservation of Pacific white shrimp (Penaeus vannamei) by pullulan and melleolide composite preservatives

Preservation of Pacific white shrimp (Penaeus vannamei) by pullulan and melleolide composite preservatives

PvMR1, a novel C-type lectin plays a crucial role in the antibacterial immune response of Pacific white shrimp, Penaeus vannamei

C-type lectins (CTLs) are important immune molecules in innate immune, which participate in non-self recognition and clearance of pathogens. Here, a new CTL with two distinct C-type lectin domains (CTLDs) from Pacific white shrimp Penaeus vannamei, designated as PvMR1 was identified. The obtained PvMR1 coding sequence (CDS) was 1044 bp long encoding a protein with 347 amino acids. PvMR1 had two CTLD, a conserved mannose-specific EPN motif and a galactose-specific QPD motif, clustering into the same branch as the crustacean CTLs. PvMR1 was widely distributed in shrimp tissues with the highest transcription level in the hepatopancreas, with significantly induced mRNA expression on the hepatopancreas and intestines after immune challenge with Vibrio anguillarum. In vitro assays with recombinant PvMR1 (rPvMR1) protein revealed that it exhibited a wide range of antimicrobial activity, bacterial binding ability, and bacterial agglutination activity in a Ca2+-independent manner. Moreover, PvMR1 promoted bacterial phagocytosis in hemocytes. Furthermore, rPvMR1 treatment could significantly enhance the bacterial clearance in hemolymph and greatly improved the survival of shrimp under V. anguillarum infection in vivo. These results collectively suggest that PvMR1 plays an important role in antibacterial immune response of P. vannamei.

The effects of dietary black cumin (Nigella sativa) seed meal on immune response of Pacific white shrimp (Penaeus vannamei)

ABSTRACT The black cumin (Nigella sativa) seed (BCS) is known as an immunostimulant herb owing to its enhancing effects on nonspecific immune systems. However, the effectiveness of dietary BCS on shrimp immune systems has not been well known. Therefore, the present study evaluated the effects of the experimental diets containing 0 (control), 5 (BCS5), 15 (BCS15), 30 (BCS30), and 50 (BCS50) g kg−1 (BCS) on immune response of Pacific white shrimp (Penaeus vannamei). The results showed significant decrease in plasma glucose, globulin, ALP activity and hyaline cells and increase of semigranular cells in shrimp fed up to 30 g kg−1 BCS compared to the control group (p < 0.05). Moreover, significant upregulation of α2-macroglobulin (α2-M), integrin β, and peroxinectin (PX) transcripts was observed during the course of the experiment in all treatments (p < 0.05). The transcripts of PX and integrin β showed a significant decrease in BCS fed shrimp after exposure to V. harveyi (p < 0.05). In conclusion, supplementation of BCS in the diet of shrimp for 90 days and after exposure to V. harveyi could significantly affect some immunological indices and the expression of some immunity related biomarkers.

Effects of including of Japanese Pumpkin Seeds and Pomace in the Diets of Pacific White Shrimp (Penaeus vannamei).

A 60-day feeding trial was conducted to evaluate the effects of including pumpkin seeds and pomace in the diets of Pacific white shrimp Penaeus vannamei, and the effects of these supplements on growth performance, body composition, and total polyphenol, flavonoid and carotenoid contents, as well as on total antioxidant activity, and body color parameters. Five diets were evaluated: pumpkin seeds (PS) at 50 and 100 g·kg-1, pumpkin pomace (PP) at 50 and 100 g·kg-1, and a control treatment. Pacific white shrimp (P. vannamei) juveniles (0.60 ± 0.01 g) were stocked in 15 tanks (310 L), containing 30 shrimps per tank, and the treatments were randomly distributed in triplicate. At the end of the experiment, shrimps were euthanized, weighed, and dissected for further analyses. The inclusion of PS in the diets impaired growth performance, reduced the total flavonoid content and had a pro-oxidative effect on muscle. The inclusion of PP in the diets did not affect growth performance, improved the feed conversion ratio, increased the total flavonoid content in the diets and hepatopancreas, and improved the antioxidant activity of the feeds and shrimp muscle. The total carotenoid content of the feeds increased with the inclusion of PS or PP in the diets; however, the total carotenoid content of shrimp increased only in those fed PP diets. Shrimp fed with PS diets showed a yellowish color and higher saturation when fresh and a reddish color and yellow hue angle after cooking. Shrimp fed PP diets turned reddish and yellowish, both when fresh and after cooking. The inclusion of PS in P. vannamei diets is not recommended; however, PP can be included at 100 g·kg-1 without affecting the growth parameters. Further studies evaluating the inclusion of higher PP levels in shrimp diets are recommended.

Effect of different types of bacterial single cell protein on feed intake, digestibility, growth and body composition of Pacific white shrimp (Penaeus vannamei)

This study assessed the potential of four bacterial (Methylococcus capsulatus) single cell protein (SCP) products as alternative protein sources for Pacific white shrimp (Penaeus vannamei) diets. A growth trial and a digestibility trial were undertaken, during which the bacterial SCP products were compared with a high-quality fishmeal and a soy protein concentrate, regarding their impact on ingredient digestibility, growth, feed intake and whole-body composition of juvenile P. vannamei. Seven diets were formulated; one reference diet (REF) and six test diets. The test diets consisted of 85% of the REF diet and 15% of a test ingredient. Ingredients tested were four bacterial SCP products (SCP1–4), which differed in processing conditions, fishmeal (FM) and soy protein concentrate (SoyProt). Growth and feed utilization were similar for P. vannamei fed either the FM diet or one of the bacterial SCP diets, whilst lowest growth and feed utilization were observed for shrimp fed the SoyProt diet. Final whole-body protein content did not differ between shrimp fed the FM diet or one of the four bacterial SCP diets. However, shrimp fed the SCP diets had a significantly higher final phosphorus body content and a higher phosphorus retention than shrimp fed the FM or SoyProt diets. This indicates a higher phosphorus availability in the bacterial SCP products compared to FM and SoyProt. Protein digestibility of the SCP products was similar to FM, whilst amino acid (AA) digestibility was comparable to FM for three of the four SCP products (SCP1, SCP2 and SCP4). The SCP3 product showed the lowest digestibility for most AA, indicating a possible influence of processing conditions on AA availability of bacterial SCPs. Overall, this study highlights that bacterial SCP originating from M. capsulatus is a viable alternative protein source for Pacific white shrimp diets, but processing conditions should be taken into account.

PSXII-4 Genomic Improvement of Disease Resistance Using Two Breeding Strategies in a Population of Penaeus Vannamei (Pacific White shrimp): a Simulation Study

Abstract This study aimed to investigate the impact of SNP density chip and genotyping strategies on the accuracy of genomic estimated breeding values (EBV) in a simulated population mimicking a commercial Pacific white shrimp (Penaeus vannamei) breeding program. The chromosome number and length mimicked the P. vannamei genome. To create an initial linkage disequilibrium (LD), a historical population of 5,000 animals was randomly bred for 1,000 generations and included a bottleneck on generation 750. In the last generation of the historical population, animals were randomly selected to create a breeding population with an effective population size (Ne) of 40. From the breeding population, a total of 40,000 animals were simulated over 20 generations. Phenotypes for a trait with a heritability of 0.1 was simulated, and genetic variance was 100% explained by 1,000 QTLs. Phenotypes and genotypes were saved for all animals in the last 10 generations, while pedigree from all 20 generations was used. To mimic the selection of young animals, a forward-in-time prediction was implemented by masking the phenotypes from the 20th generation in the data analysis. The accuracy of prediction was the correlation between the simulated true breeding value and the EBV in the last generation. Genomic information consisted of SNP chips with 6K, 11K, 22K, 45K, and 90K markers evenly spaced across the genome. The two breeding strategies considered in this study were 1) 25 families with 40 animals each, and 2) 50 families with 20 animals each. Additionally, the number of generations with phenotypes varied from nine to one. This was done to identify the minimum number of generations to collect data, as phenotyping individuals may be challenging in aquaculture. In all scenarios, genomic selection outperformed family selection. Results indicated that genotyping more individuals within families, instead of more families with fewer individuals, improved the accuracy of predictions. Furthermore, the maximum accuracy was achieved with 45K and 90K SNPs in both scenarios, showing that SNP density will reach a plateau. Finally, maximum accuracy plateaued at five generations. Finally, having one generation with phenotypes and genotypes yielded greater accuracies than nine generations with only phenotypes. Overall, the results from the present study suggest that genomic selection using the single-step genomic best linear unbiased prediction (ssGBLUP) methodology is a feasible tool to improve P. vannamei commercial populations, even for traits with low heritability. Moreover, it is recommended to collect data on more individuals per family than increasing the number of families, and data collection should be continued for at least four generations. Tests with real data will provide further insights into the ideal number of animals and SNP density necessary for maximum accuracy.

Functional Effects of Hydrolyzable Tannins on the Growth, Health Status, and Hepatopancreas Histology of Pacific White Shrimp Penaeus vannamei Reared under Commercial Pond Conditions

In the present study, the functional effects of hydrolyzable tannins (HT) extracted from the sweet chestnut tree Castanea sativa were evaluated either by directly incorporating them into the diet or by using a top-dressing application on the growth, body composition, total hemocyte counts, lysozyme activity, and histomorphological condition of the hepatopancreas of Pacific white shrimp Penaeus vannamei. Shrimp was confined in hapa nets installed within commercial outdoor ponds for 90 days. Eight experimental diets included a basal formulated diet (BD) with varying inclusion levels of HT (BD-0%, BD-0.1%, BD-0.2%, and BD-0.3%), a low fish meal (FM) diet with reduction on the inclusion level of FM from 10% to 7.5% and labeled as LFM 0.3% HT, a top-dressing HT application (TC) on basal diet (BDTD-0.4% HT), and a commercial diet (CDTD-0% HT and CDTD-0.4% HT). The final body weight (FBW), percentage weight gain (PWG), thermal growth coefficient (TGC), average daily growth (ADG), and feed conversion ratio (FCR) were significantly better in the group of shrimp fed with BD-0.3% HT compared to BD-0% HT. The administration of CD-0.4% HT was able to enhance the growth performance of shrimp compared to BD-0% HT and CD without HT. Higher protein and fat contents were found in the body of shrimp fed with graded levels of HT compared to shrimp fed with BD or CD without HT. Numerically, the direct inclusion and top-dressing process of HT increased the total hemocyte count and lysozyme activity in shrimp. Both BDTD-0.4% HT and CDTD-0.4% HT were also able to support a better hepatopancreatic condition with reference to histomorphology and integrity. These results indicated that BD-0.3% HT inclusion could significantly improve the growth performance and prevent the alteration in health and histomorphological condition of the hepatopancreas of shrimp P. vannamei cultured in hapa nets under commercial farm conditions, but also 0.4% HT could be used as a supplementation dosage for the top-dressing process in diets.

Protection of Pacific white shrimp (Penaeus vannamei) against white spot syndrome virus infection by nitric oxide-generating compound S-nitrosoglutathione

Nitric oxide (NO), a highly reactive free radical generated endogenously by nitric oxide synthase (NOS), plays crucial roles in immune defense against a broad range of pathogens including viruses, bacteria, fungi, and protozoans. However, the regulation and effect of NO during viral infection in invertebrates remain largely unexplored. White spot syndrome virus (WSSV) is one of the most severe pathogens affecting the global shrimp farming industry. Our study shows that NO production in Pacific white shrimp Penaeus vannamei decreases during WSSV infection. Reducing NO production using the NOS inhibitor N-nitro-L-arginine methyl ester (L-NAME) significantly promotes WSSV replication in primary culture of hemocytes isolated from P. vannamei. This effect is partically reversed by L-arginine, a native substrate for NOS, indicating that L-NAME's immunity-reducing action is NO-dependent. In vitro studies also reveal inhibition of WSSV replication in the presence of three NO donors: S-nitrosoglutathione (GSNO), S-nitro-N-acetylpenicillamine (SNAP), and diethylenetriamine nitric oxide adduct (DETA/NO). The involvement of NO in anti-WSSV protection is further demonstrated by an in vivo study where dietary supplementation with GSNO at non-toxic doses increases NO levels and reduces viral load and mortality in WSSV-challenged shrimp. Our results contribute to understanding the antiviral activity of NO in invertebrates and provide a theoretical basis for developing NO-based therapeutic strategies to control WSSV infection.

Substituting dietary fishmeal with silkworm pupae meal in diets of Pacific white shrimp (Penaeus vannamei): Effects on growth performance, nutrient utilisation, whole-body composition and digestive enzyme activities

The present study evaluated the dietary substitution effect of silkworm pupae meal (SWP) forfish meal (FM) on growth performance, feed utilisation, whole-body proximate composition,amino acid profile and digestive enzyme activities of Pacific white shrimp (Penaeusvannamei). The shrimp were fed with six isonitrogenous (36% crude protein), isolipidic (8%crude lipid) and isocaloric (16 MJ kg-1) experimental diets, containing 0, 20, 40, 60, 80 and100% SWP, respectively, to replace dietary FM. A total of 360 shrimps (average initial weightof 3.86±0.20 g) were distributed into 18 tanks (20 shrimp per tank). The experimental dietswere fed to triplicate groups of P. vannamei three times a day until satiation for 45 days.Significantly (p&lt;0.05) higher growth performance and feed utilisation were found in shrimpfed diet with 60% incorporation level of SWP meal. No significant differences (p&gt;0.05) wereobserved in the survival rate, whole-body proximate composition and amino acid profile ofshrimp fed SWP meal-incorporated diets. Additionally, higher specific activities of digestiveenzymes such as amylase, trypsin and lipase were observed in shrimps fed diet with 60%incorporation level of SWP meal. The present study revealed that dietary fish meal proteinup to 60% can be substituted with SWP without compromising growth performance, feedutilisation, whole-body proximate composition, amino acid profile and digestive enzymeactivities of Pacific white shrimp fed on SWP meal based diets. Keywords:Amylase, Feed ingredient, Waste utilisation,Weight gain

WSV403 suppresses JAK/STAT signaling to impair antiviral resistance in Pacific white shrimp Penaeus vannamei

Viral immediate early (IE) genes are key regulators of host antiviral defenses. White spot syndrome virus (WSSV) IE gene WSV403 encodes an E3 ligase which regulates the latency state of WSSV. However, the role of WSV403 in host immune response remains unclear. Here, we generated a transgenic Drosophila line that overexpresses WSV403 and found that WSV403 suppresses the JAK/STAT pathway and its downstream genes, leading to increased susceptibility and viral load upon Drosophila C virus infection. We further showed that WSV403 suppresses Stat92E expression without affecting its phosphorylation or degradation, suggesting a novel mechanism of JAK/STAT inhibition. Moreover, we demonstrated that knockdown of WSV403 in the Pacific white shrimp Penaeus vannamei reduces WSSV replication and enhances transcript levels of JAK/STAT pathway components. Our results revealed the immune modulatory function of WSV403 and uncovered a new mechanism by which WSSV inhibits host JAK/STAT signaling to impair antiviral resistance against WSSV infection.