White Shrimp Litopenaeus Vannamei Research Articles

Effect of supersaturated dissolved oxygen on growth-, survival-, and immune-related gene expression of Pacific white shrimp (Litopenaeus vannamei).

Oxygen concentration is an essential water quality parameter for aquaculture systems. Recently, supersaturated dissolved oxygen (DO) has been widely used in aquaculture systems to prevent oxygen depletion; however, the long-term effects of supersaturated DO exposure on aquatic animals have not been studied. In this study, we examined the effects of supersaturated DO on the growth, survival, and gene expression of Pacific white shrimp (Litopenaeus vannamei). Specific pathogen-free shrimp with a body weight of 8.22 ± 0.03 g were randomly assigned to two groups with four replicates at a density of 15 shrimps per tank. Shrimp were cultivated in recirculating tanks containing 50 L of 15 ppt seawater in each replicate. Oxygen was supplied at 5 mg/L to the control tanks using an air microbubble generator and at 15 mg/L to the treatment tanks using a pure oxygen microbubble generator. Shrimp were fed commercial feed pellets containing 39% protein at 4% of their body weight per day for 30 days. Average daily growth (ADG) and feed conversion ratio (FCR) were determined on days 15 and 30. Shrimp molting was measured every day. Individual hemolymph samples were obtained and analyzed for total hemocyte count, differential hemocyte count, and expression of growth- and immune-related genes at the end of the experiment. Long-term exposure to supersaturated DO significantly affected shrimp growth. After 30 days of supersaturated DO treatment, the final weight and ADG were 14.73 ± 0.16 g and 0.22 ± 0.04, respectively. Shrimp treated with normal aeration showed significantly lower weight (12.13 ± 0.13 g) and ADG (0.13 ± 0.00) compared with the control group. FCR was 1.55 ± 0.04 in the treatment group and 2.51 ± 0.09 in the control group. Notably, the shrimp molting count was 1.55-fold higher in the supersaturated DO treatment than in the supersaturated DO treatment. The expression of growth-related genes, such as alpha-amylase, cathepsin L, and chitotriosidase, was 1.40-, 1.48-, and 1.35-fold higher, respectively, after supersaturated DO treatment. Moreover, the treatment increased the expression of anti-lipopolysaccharide factor, crustin, penaeidin3, and heat shock protein 70 genes by 1.23-, 2.07-, 4.20-, and 679.04-fold, respectively, compared to the controls. Supersaturated DO increased growth and ADG production and decreased FCR. Furthermore, enhanced immune-related gene expression by supersaturated DO may improve shrimp health and reduce disease risk during cultivation.

Effects of Difference C/N Ratio on Water Quality of White Leg Shrimp (Litopenaeus vannamei) Cultivation

Biotechnology is used to apply technology to the C/N ratio by stimulating the activities of heterotrophic microorganisms, which derive food from carbon and nitrogen substrates in a certain ratio. The goal of this research was to see how the optimal carbon-nitrogen ratio affected water quality and floc volume in white leg shrimp (Litopenaeus vannamei) farming. This study took place in the UPT Integrated Laboratory Unkhair in Ternate City in July and August 2021. A fully randomized design (CRD) with four treatments and three replications was used in this investigation. Different C/N ratios had an effect on ammonia, nitrite, nitrate, floc volume, and feed conversion ratio, according to the research. The water quality parameters are still suitable for white leg shrimp cultivation. In white leg shrimp culture, the addition of C-organic molasses (different C/N ratios) was able to reduce the concentrations of (NH3), (NO2), and (NO3), and also greatly increase the flock volume and streamline the feed conversion ratio.

RNA sequencing and LncRNA identification in muscle of the Pacific white shrimp Litopenaeus vannamei at different growth rates

As a typical crustacean species, the growth of the Pacific white shrimp Litopenaeus vannamei has important economic and scientific value. Muscle growth in L. vannamei is regulated by a complex network of transcriptional and post-transcriptional processes. Although many genes have been found to be involved in shrimp muscle growth, their regulatory mechanisms remain largely unexplored. In this study, we compared gene expression differences in L. vannamei muscle with different growth rates, and identified a total of 2419 differentially expressed genes (DEGs). These DEGs were found to be associated with muscle growth, molting, epidermal structure, and immune and stress response. Furthermore, we discovered 9673 candidate lncRNAs in muscle, which showed distinct transcript characteristics compared to mRNAs. Among these, 1324 differentially expressed lncRNAs may affect muscle growth by regulating gene expression in cis- or trans-mode at the transcriptional level. For example, the lncRNA MSTRG.15718.1 was found to potentially affect muscle growth by regulating nearby genes. Our analyses enabled the discovery of novel genes and lncRNA regulatory networks that affect shrimp growth. These results not only provide new insights into the mechanism of shrimp muscle growth but also offer valuable clues for molecular breeding of shrimp growth traits.

Dietary β-Glucan Alleviates Antibiotic-Associated Side Effects by Increasing the Levels of Antioxidant Enzyme Activities and Modifying Intestinal Microbiota in Pacific White Shrimp (Litopenaeus vannamei).

Antibiotics and their secondary metabolites are commonly found in aquatic ecosystems, leading to the passive exposure of many aquatic animals to low doses of antibiotics, which can affect their health. However, there is limited information available on how to mitigate the side effects of antibiotics on normal aquatic animals. This study aimed to investigate the potential of dietary β-glucan to alleviate the side effects induced by antibiotics in Pacific white shrimp (Litopenaeus vannamei) (0.37 ± 0.02 g). A six-week feeding trial was conducted with four dietary treatments including a control, 1 g/kg β-glucan (β-glucan), 50 mg/kg oxytetracycline (OTC), and a combination of 50 mg/kg OTC and 1 g/kg β-glucan (Mix) groups. At the end of the trial, the growth performance, intestinal microbial composition, antioxidant capacity, and immune response of the shrimp were assessed. There were no significant differences in growth performance among the groups, but the condition factor of the shrimp in the Mix group was significantly decreased when compared to the control and β-glucan groups. The activities of hepatopancreas catalase (CAT) and serum phenol oxidase in the OTC group were significantly lower than those in the control group. On the other hand, the activities of hepatopancreas superoxide dismutase and CAT enzymes in the β-glucan group were significantly higher than those in the OTC group. The supplementation of β-glucan in combination with antibiotics significantly increased the CAT activity and bacteriolytic activity compared to the OTC and control groups, respectively. Moreover, an analysis of the intestinal microbiota revealed that the Observed_species estimator in the Mix group was significantly higher than that in the control group. Dietary antibiotics significantly increased the abundance of Actinobacteria at the phylum level, but the Mix group showed no significant difference. The supplementation of β-glucan in combination with antibiotics also significantly increased the relative abundance of Meridianimaribacter compared to the control group. Additionally, the synergistic influence of β-glucan with antibiotics increased the beta diversity of intestinal microbiotas. These findings suggest that the supplementation of β-glucan in combination with antibiotics on Pacific white shrimp can alleviate the low antioxidant capacity and immune response caused by antibiotics while enhancing the intestinal microbial composition. This provides a potential solution to mitigate the negative impacts of antibiotics in aquaculture.

Dietary administration of yeast (Saccharomyces cerevisiae) hydrolysate from sugar byproducts promotes the growth, survival, immunity, microbial community and disease resistance to VP (AHPND) in Pacific white shrimp (Litopenaeus vannamei)

This study investigated the effects of yeast hydrolysate (YH) from sugar byproducts on various parameters in Pacific white shrimp (Litopenaeus vannamei). The study found no significant differences in water quality parameters across all treatment tanks, ensuring that the observed effects were not due to environmental variations. There were no significant differences in growth parameters between the control group and groups receiving YH at different dosages. However, the group given YH at 10.0 g/kg feed exhibited a notably higher survival rate and higher expression of growth-related genes (IGF-2 and RAP-2A) in various shrimp tissues. YH was associated with enhanced immune responses, including lysozyme activity, NBT dye reduction, bactericidal activity, and phagocytic activity. Notably, the 10.0 g/kg feed group displayed the highest phagocytic index, indicating a dose-dependent immune response. Expression of immune-related genes (ALF, LYZ, ProPO, and SOD) was upregulated in various shrimp tissues. This upregulation was particularly significant in the gills, hepatopancreas, intestine, and hemocytes. While total Vibrio counts remained consistent, a reduction in green Vibrio colonies was observed in the intestine of shrimp treated with YH. YH, especially at 5.0 and 10.0 g/kg feed dosages, significantly increased survival rates and RPS values in response to AHPND infection. The findings of this study suggest that incorporating additives derived from yeast byproducts with possible prebiotic properties obtained from sugar byproducts can lead to positive results in terms of enhancing growth performance, immunity, histological improvements, and resistance to V. parahaemolyticus, the causative agent of acute hepatopancreatic necrosis disease (AHPND).

Different protein levels in a super-intensive culture of juvenile Pacific white shrimp (Litopenaeus vannamei) in biofloc systems during the early rearing phase

The determination of crude protein level in diets of aquatic organisms allows maximizing growth, decreasing feed costs and improving water quality. A nursery culture of Litopenaeus vannamei was carried out in superintensive biofloc systems using five diets with different protein levels (320 g kg-1 CP, 360 g kg-1 CP, 400 g kg-1 CP, 440 g kg-1 CP and 480 g kg-1 CP); each diet was used in quadruplicates. The experimental period lasted 35 days, and the shrimps (0.59± 0.001 g) were stocked at a density of 600 PL m-³, using 20 experimental units (50 L of useful volume). There were no significant differences in animal survival between treatments (p>0.05). The animals fed with 480 g kg-1 presented higher final weight, SGR when compared to the treatments fed with 320 g kg-1 (p<0.05). Furthermore, feeding shrimp with 32% CP diets results in a reduction in feed utilization and nutrient retention, thus increasing feed costs. Overall, the results show that it is possible to reduce the protein content of L. vannamei diets to up to 360 without affecting the zootechnical performance, survival and antioxidant capacity of the animals.

Effect of Liquid Nitrogen Freezing Temperature on the Muscle Quality of Litopenaeus vannamei.

The implications of different liquid nitrogen freezing (LNF) temperatures (-35 °C, -65 °C, -95 °C, and -125 °C) on the ice crystal and muscle quality of white shrimp (Litopenaeus vannamei) were investigated in this essay. The results showed that better muscle quality was maintained after LNF treatment compared to that after air blast freezing (AF) treatment. As the freezing temperature of liquid nitrogen decrease, the freezing speed accelerated, with the freezing speed of LNF at -125 °C being the fastest. However, an excessively fast freezing speed was not conducive to maintaining the quality of shrimp. Among all the freezing treatments, LNF at -95 °C led to the lowest thawing losses and cooking losses, and the highest L* values, indicating that LNF at -95 °C could keep the water holding capacity of frozen shrimp better than that with other freezing methods. At the same time, LNF at -95 °C resulted in higher water holding capacity, and hardness values for shrimps than those with other frozen treatments (p < 0.05). In addition, the results of the water distribution of shrimps showed that treatment with a -95 °C LNF reduced the migration rate of bound and free water. Meanwhile, the microstructural pores of shrimps in the -95 °C LNF group were smaller, indicating that the ice crystals generated during -95 °C LNF were relatively smaller than those generated via other frozen treatments. In conclusion, an appropriate LNF temperature (-95 °C) was beneficial for improving the quality of frozen shrimp, and avoiding freezing breakage.

Differential Toxicity Responses between Hepatopancreas and Gills in Litopenaeus vannamei under Chronic Ammonia-N Exposure.

Ammonia nitrogen is one of the main toxic substances in aquatic cultivation environments. Chronic exposure to excessive amounts of ammonia-N creates toxic consequences, retarding the growth of aquatic organisms. This study investigated the growth performance, morphological and physiological alterations, and transcriptome changes in the hepatopancreas and gills of white shrimp Litopenaeus vannamei. The results showed that there was no significant difference in the survival rate (p > 0.05), whereas growth performance was reduced significantly in the treated groups compared to the control groups (p < 0.05). Significant structural damage and vacuolation occurred in hepatopancreas and gill tissues in the treated groups. Superoxide dismutase (SOD) activity and Na+/K+-ATPase content were significantly increased by chronic ammonia-N exposure in the two tissue groups. In addition, catalase (CAT) activity and malondialdehyde (MDA) levels were significantly altered in the hepatopancreas groups (p < 0.05), whereas no differences were observed in the gill groups (p > 0.05). There were 890 and 1572 differentially expressed genes identified in the hepatopancreas (treated versus control groups) and gills (treated versus control groups), respectively, of L. vannamei under chronic ammonia-N exposure. Functional enrichment analysis revealed associations with oxidative stress, protein synthesis, lipid metabolism, and different serine proteases. The gills maintained cellular homeostasis mainly through high expression of cytoskeleton and transcription genes, whereas the hepatopancreas down-regulated related genes in the ribosome, proteasome, and spliceosome pathways. These genes and pathways are important in the biosynthesis and transformation of living organisms. In addition, both tissues maintained organismal growth primarily through lipid metabolism, which may serve as an effective strategy for ammonia-N resistance in L. vannamei. These results provided a new perspective in understanding the mechanisms of ammonia-N resistance in crustaceans.

Effects of Dietary β-Glucan Feeding Strategy on the Growth, Physiological Response, and Gut Microbiota of Pacific White Shrimp, Litopenaeus vannamei, under Low Salinity.

An eight-week feeding trial was conducted to investigate the effects of a dietary β-glucan application strategy on the growth performance, physiological response, and gut microbiota of Pacific white shrimp (Litopenaeus vannamei) (0.49 ± 0.17 g) under low salinity. Six feeding strategies were established, including a continuous β-glucan-free diet group (control), a continuously fed group with a 0.1% β-glucan diet (T1), and groups with the following intermittent feeding patterns: 1 day of β-glucan diet and 6 days of β-glucan-free diet (T2), 2 days of β-glucan diet and 5 days of β-glucan-free diet (T3), 3 days of β-glucan diet and 4 days of β-glucan-free diet (T4), and 4 days of β-glucan diet and 3 days of β-glucan-free diet (T5) each week. No significant differences in growth performance among all the groups were found, although the condition factor was significantly higher in the T3 group than in the T1 and T5 groups (p < 0.05). The T-AOC and GPX activities were significantly lower in the T3 group than in the control group (p < 0.05). The MDA content was also significantly lower in the T2 group than in the T3 and T4 groups (p < 0.05). Additionally, the mRNA expression of the Pen3a gene was significantly upregulated in the hepatopancreas of the T4 group compared to the control and T5 groups (p < 0.05), and the Toll gene was also significantly upregulated in the T3 group compared to the T1 and T2 groups (p < 0.05). Dietary β-glucan induced changes in the alpha diversity and composition of the gut microbiota in different feeding strategies. The beta diversity of the gut microbiota in the T2 group was significantly different from that in the control group. The results of a KEGG analysis showed that gut function in the carbohydrate metabolism, immune system, and environmental adaptation pathways was significantly enhanced in the T3 group. These findings provide evidence that the intermittent feeding strategy of β-glucan could alleviate immune fatigue, impact antioxidant ability, and change gut microbiota composition of L. vannamei under low salinity.

A high-quality genome assembly of the Pacific white shrimp (Litopenaeus vannamei) provides insights into its evolution and adaptation

The Pacific white shrimp (Litopenaeus vannamei) is the most commercially-farmed shrimp species globally and is of significant ecological and economic importance. Here we report a high-quality genome assembly of L. vannamei using PacBio reads and Hi-C data. The assembly spans 1.87 Gb with scaffold N50 of 39.7 Mb and 87% of estimated genome size is assigned to 44 pseudochromosomes. The genome contains 24,861 protein-coding genes and a high proportion of transposable elements (64.33%). Significant expansion of gene families was observed in the genome related to locomotion, vision, and neural transmission, including via expansion of actin, myosin, rhodopsin, and neurotransmitter-gated ion-channel ligand binding domain genes, potentially revealing mechanisms underlying their evolved benthic adaptations. The genome assembly of L. vannamei provides valuable resources for future genetic research, breeding, and improvement of aquaculture traits, and will facilitate the research of genetic changes during evolution.

Water profile of white shrimp (Litopenaeus vannamei) infected with white feces disease (WFD)

In mid-2021, shrimp farmer reported case of mass deaths in white shrimp (Litopenaeus vannamei) in Pasuruan Regency, reaching 2.6-3 kg/day in Kalianyar Village, Bangil District. To determine the main pathogenic bacteria that cause mass mortality and the composition of microbes on rearing media infected with certain diseases and healthy ones, this study observed the water profile of ponds which include microbial composition in it using next-generation sequencing (NGS) technology. The research was conducted by taking healthy shrimp pond water samples and infected shrimp pond water samples. These results generally indicate that the disease is similar to white feces syndrome (WFS). The results of the NGS test showed that the main causative pathogen is Vibrio vulnificus because its presence in infected pond water is quite dominant.

Xenogeneic transplantation of spermatogonia from banana shrimp (Fenneropenaeus merguiensis) into white shrimp (Litopenaeus vannamei)

Banana shrimp (Fenneropenaeus merguiensis) is one of the famous shrimps for the consumer, while larvae of F. merguiensis for farming depend on wild-caught broodstock. On the other hand, white shrimp (Litopenaeus vannamei) is propagated from a culture broodstock and has a high growth rate. Currently, spermatogonia transplantation is one of the alternative methods to preserve and propagate the offspring of several vertebrates. Transplantation technology has not been reported in shrimp. This study provided information on the transplantation technique in shrimp using F. merguiensis as a donor and L. vannamei as a recipient. Spermatogonia were prepared from wild-caught F. merguiensis, 11–12 cm in length, and the cells were 8–10 µm in diameter. The spermatogonia were injected into postlarvae days 4, 9, and 16 of L. vannamei. The PKH-26 fluorescent signal was between the heart and hepatopancreas of the recipient 4 wk post-injection. In addition, the gonad of the recipient contained the proliferated donor germ cells in the gonad of the recipient after 4.5 month post-transplantation, determined by in situ hybridization with a VASA probe. The mature transplanted shrimps had dark spots on the gonad, similar to F. merguiensis's gonad. Then, the donor-derived offspring were achieved after the natural mating of transplanted shrimp. The donor-like morphology of F1 offspring was approximately 70.5%. When the genetics of F1 offspring were clarified and revealed, 2% of F. merguiensis, 28% of L. vannamei, and 70% of the hybrid between F. merguiensis and L. vannamei. The overall results indicated the successful establishment of spermatogonia transplantation in shrimp. The benefit of this work could apply to conserve or produce this shrimp in the future.

Monitoring of microbial, water quality, and production performance of Litopenaeus vannamei on intensive pond in Bulukumba, South Sulawesi, Indonesia

The aim of the research is to monitor the dynamics of microbial number, water quality, and production performance in Pacific white shrimp (Litopenaeus vannamei) cultivation in Bulukumba, South Sulawesi Province, Indonesia, utilizing an intensive system. This research was carried out on seven Pacific white shrimp ponds over the duration of one maintenance cycle (84 days), from November 2019 to February 2020. Interestingly, the results showed that the highest total bacterial counts (TBC) were obtained in pond P3, namely in the range of 0.12-98.0×105 CFU/mL, the highest total Vibrio counts (TVC) were obtained in pond P5, namely in the range of 0.09-2.8×105 CFU/mL, luminous bacterial counts (LBC) were only found in ponds P1, P4, and P5 with the same range values, namely 0-100×103 CFU. The best performance of Pacific white shrimp production was found in pond P2, with a percentage of survival rate (SR) and productivity of 65 percent and 4074.5kg/ha, respectively, and the worst was found in pond P5, with a percentage of survival rate (SR) and productivity of 35 percent and 2583.66 kg/ha, respectively. Finally, the intense culture system used for Pacific white shrimp accumulates dynamics that may alter microbiology, water quality, and production performance.

Identification of an Ortholog of MALT1 from Shrimp That Induces NF-κB-Mediated Antiviral Immunity.

MALT1 (mucosa-associated lymphoid tissue lymphoma translocation protein 1) serves as a pivotal mediator for NF-κB activation in response to a wide spectrum of transmembrane receptor stimuli. In the present study, a homolog of MALT1, named LvMALT1, is cloned from the Pacific white shrimp (Litopenaeus vannamei) and its potential function in shrimp innate immunity is explored. The open reading frame of LvMALT1 is 2364 bp that encodes 787 amino acids. The predicted LvMALT1 protein structure comprises a death domain, three immunoglobulin domains, and a caspase-like domain, exhibiting remarkable similarity to other homologs. LvMALT1 is a cytoplasmic-localized protein and could interact with LvTRAF6. Overexpression of LvMALT1 induces the activation of promoter elements governing the expression of several key antimicrobial peptides (AMPs), including penaeidins (PENs) and crustins (CRUs). Conversely, silencing of LvMALT1 leads to a reduction in the phosphorylation levels of Dorsal and Relish, along with a concomitant decline in the in vivo expression levels of multiple AMPs. Furthermore, LvMALT1 is prominently upregulated in response to a challenge by the white spot syndrome virus (WSSV), facilitating the NF-κB-mediated expression of AMPs as a defense against viral infection. Taken together, we identified a MALT1 homolog from the shrimp L. vannamei, which plays a positive role in the TRAF6/NF-κB/AMPs axis-mediated innate immunity.

Identifying genes involved in the secretory physiological response to feeding in Pacific White Shrimp (Litopenaeus vannamei) using transcriptomics

The physiological response to feeding is important for production aspects that include feed utilization and growth, and the responses require the action of numerous secretory factors. However, as an important aquaculture animal, the secretory response of Pacific White Shrimp (Litopenaeus vannamei) after feeding has not been comprehensively characterized. In this study, transcriptome analysis showed that 3172 differentially expressed genes were involved in the post-feeding response, including 289 new genes not annotated in the L. vannamei reference genome. Subsequently, 715 differentially expressed secretory reference genes and 18 new differentially expressed secretory genes were obtained through the identification of signal peptides in secreted proteins. Functional classification revealed that differentially expressed secretory genes were enriched in pathways pertaining to lipid metabolism (20 genes), carbohydrate metabolism (21 genes), glycan biosynthesis and metabolism (27 genes), digestive system (40 genes), and transport and metabolism (43 genes). The 14 pathways most enriched by differentially expressed secretory genes involved 83 genes, 71 of which encoded enzymes involved in food digestion and metabolism. Specific enzymes such as lipase 3-like and NPC intracellular cholesterol transporter 1-like in lipid metabolism, alpha-amylase-like and glucosylceramidase-like in carbohydrate metabolism, and cysteine proteinase 4-like and trypsin-1-like in the digestive system were found to be differentially expressed. Furthermore, we discovered a new gene, MSTRG.2504, that participates in the digestive system and carbohydrate metabolism. The study provides valuable insights into the secretory response (especially metabolism-related enzymes) to feeding in L. vannamei, uncovering the significant roles of both known and new genes. Furthermore, this study will improve our understanding of the feeding physiology of L. vannamei and provide a reference basis for further feeding endocrine research in the future.

Effect of static magnetic field-assisted freezing at different temperatures on muscle quality of pacific white shrimp (Litopenaeus vannamei)

The effect of static magnetic field-assisted freezing (MF) at different temperatures (−35, −30, −25, and −20 °C) on the muscle quality of pacific white shrimp (Litopenaeus vannamei) was evaluated to investigate the possibility of energy saving by MF. The results showed that the −35 °C MF treatment increased the water-holding capacity of shrimp muscle, and maintained the wholeness of the microstructure compared to −35 °C immersion freezing (control group, IF). With the increase in freezing temperature in the MF treatments, the size of ice crystals gradually increased, and the sensory properties of shrimp decreased. The water-holding capacity, sensory properties, and water distribution of shrimp muscle subjected to MF at −25 °C were still no significantly different from those of the IF at −35 °C (P > 0.05). In summary, the utilization of MF enhanced the quality of frozen pacific white shrimp, which has the potential to provide energy saving benefits.

Evaluation of High Stocking Densities on the Water Quality and Growth Performance of Pacific White Shrimp Litopenaeus vannamei Reared in a Mixotrophic Biofloc Nursery System

The present study aimed to explore the effects of intensive culture densities on the water quality and growth performance of the Pacific white shrimp Litopenaeus vannamei reared in a mixotrophic biofloc system (heterotrophic/chemoautotrophic) at three stocking rates of 5,000, 4,000, and 3,000 PL/m3 (namely G5000, G4000, and G3000, respectively) for 21 days. At the end of the study, the mean values of water temperature, dissolved oxygen, dissolved oxygen saturation level, pH, oxidation-reduction potential, free carbon dioxide, alkalinity, total ammonia nitrogen (TAN), nitrite-nitrogen (NO2-N), nitrate-nitrogen, and settleable solids did not substantially differ among study groups ( p &gt; 0.05 ). In addition, the highest mean levels of TAN and NO2-N recorded were 1.27 mg/l (G4000) and 9.23 mg/l (G3000), respectively. The results of growth performance revealed that final body weight, weight gain, weekly growth rate, and specific growth rate were not affected by the studied densities ( p &gt; 0.05 ). Although no significant differences were observed ( p &gt; 0.05 ), the G3000 treatment exhibited the highest survival rate (80.66% ± 8.56%), followed by G4000 (75.05% ± 0.31%) and G5000 (71.63% ± 2.11%). However, the shrimp yield was meaningfully higher for G5000 treatment (1.72 ± 0.0.09 kg/m3, 0.69 ± 0.03 kg/m2) compared with G3000 group (1.27 ± 0.0.12 kg/m3, 0.48 ± 0.04 kg/m2) ( p &lt; 0.05 ). Our results indicate L. vannamei can be reared at intensive nursery densities of up to 5,000 PL/m3 (2,000 PL/m2) until reaching 0.5 g without significant retardation in water quality, growth, and survival.

Effect of Fly Maggot Protein as Dietary on Growth and Intestinal Microbial Community of Pacific White Shrimp Litopenaeus vannamei.

As the intensive development of aquaculture persists, the demand for fishmeal continues to grow; however, since fishery resources are limited, the price of fishmeal remains high. Therefore, there is an urgent need to develop new sources of protein. They are rich in proteins, fatty acids, amino acids, chitin, vitamins, minerals, and antibacterial substances. Maggot meal-based diet is an ideal source of high-quality animal protein and a new type of protein-based immune enhancer with good application prospects in animal husbandry and aquaculture. In the present study, we investigated the effects of three different diets containing maggot protein on the growth and intestinal microflora of Litopenaeus vannamei. The shrimp were fed either a control feed (no fly maggot protein added), FM feed (compound feed with 30% fresh fly maggot protein added), FF feed (fermented fly maggot protein), or HT feed (high-temperature pelleted fly maggot protein) for eight weeks. The results showed that fresh fly maggot protein in the feed was detrimental to shrimp growth, whereas fermented and high-temperature-pelleted fly maggot protein improved shrimp growth and survival. The effects of different fly maggot protein treatments on the intestinal microbiota of L. vannamei also varied. Fermented fly maggot protein feed and high-temperature-pelleted fly maggot protein feed increased the relative abundance of Ruegeria and Pseudomonas, which increased the abundance of beneficial bacteria and thus inhibited the growth of harmful bacteria. In contrast, fresh fly maggot proteins alter the intestinal microbiome, disrupting symbiotic relationships between bacteria, and causing invasion by Vibrio and antibiotic-resistant bacteria. These results suggest that fresh fly maggot proteins affect the composition of intestinal microorganisms, which is detrimental to the intestinal tract of L. vannamei, whereas fermented fly maggot protein feed affected the growth of L. vannamei positively by improving the composition of intestinal microorganisms.

Glutathione-rich yeast hydrolysate makes the contributions to growth performance, healthy of Pacific white shrimp (Litopenaeus vannamei), and helps shrimp resist nitrite stress

Seven diets were formulated to investigate the effects of glutathione-rich yeast hydrolysate (GYH) on growth performance, antioxidant capacity, and innate immunity of Litopenaeus vannamei. Based on the control diet (28% fishmeal content, CON), six diets supplement with GYH 0% (G0), 0.3% (G0.3), 0.5% (G0.5), 0.7% (G0.7), 0.9% (G0.9) and 1.1% (G1.1) were prepared after cottonseed protein concentrate replacing fishmeal 28.5% of the CON. After the 8 weeks feeding experiment, the shrimp fed diet containing 0.5%− 0.9% GYH obtained better growth performance compared to the CON and G0 groups, as well as the significantly lower feed conversion rate (P < 0.05). The intestinal villus height of shrimp fed diet with 0.3–0.9% GYH was significantly higher than the G0 group (P < 0.05). Decreased serum malondialdehyde content and significantly increased total antioxidant capacity, reduced glutathione content, activity of glutathione peroxidase and phenoloxidase in the hepatopancreas were found in shrimp fed diet with 0.7–0.9% GYH (P < 0.05). In addition, supplement 0.5–0.9% GYH significantly upregulated the expression levels of genes igf-1, pi3k, akt, tor, s6k1, and 4ebp1 in muscle and increased the crude protein content of the whole shrimp (P < 0.05). The expression levels of genes lgbp, proPO and lzm in the hepatopancreas were significantly upregulated in shrimp fed 0.7% GYH supplement (P < 0.05). Serum CAT activity in the G0.9 group was significantly higher than that of the G0 group before and after nitrite stress (P < 0.05). The shrimp fed diet supplemented with 0.5–1.1% GYH exhibited better intestinal tissue structure compared to groups CON and G0 after nitrite stress. In conclusion, the optimum level of dietary GYH was 0.67% based on the analysis of the quadratic term fitting results of weight gain rate. The diets supplemented with appropriate GYH could contribute to the growth and health of shrimp.

Different lipid levels in the Pacific white shrimp (Litopenaeus vannamei) nursery in systems grown in super-intensive biofloc systems

High stocking densities can decrease growth, feed conversion, and depletion of the shrimp immune system, therefore lipids can serve as a highly energetic source capable of meeting the metabolic demands of cultured organisms. This work aimed to evaluate the influence of different lipid levels (50 g kg−1, 70 g kg−1, 90 g kg−1, 110 g kg−1, and 130 g kg−1 extract ether-EE) in diets of Litopenaeus vannamei post-larvae raised in super-intensive biofloc systems, on growth, antioxidant capacity, and feeding costs. The experimental period lasted 30 days and the shrimp of 0.018 ± 0.001 g (PL 20) were stored (5000 PL m-³) in 20 tanks (50 L) in quadruplicates. Significant differences in water quality were not recorded (P > 0.05). The final weight and weight gain were not affected by the different treatments; however, the lowest survival rates were found in the 110 EE and 130 EE treatments and the 50 and 70 EE treatments had the highest productivity and lowest feeding cost (P < 0.05). Furthermore, no significant differences were found in the antioxidant capacity against peroxide radicals (ACAP) and thiobarbituric acid reactive species (TBARS) results (P > 0.05), which might be related to a protective effect proportionated by the biofloc consumption. The quadratic regression for productivity indicated that dietary lipid requirements for L. vannamei nursery is 67.8 g kg−1.