Pacific White Shrimp Litopenaeus Vannamei Research Articles

Growth Performance, Feed Utilisation, Endogenous Digestive Enzymes, Intestinal Morphology, and Antimicrobial Effect of Pacific White Shrimp (Litopenaeus vannamei) Fed with Feed Supplemented with Pineapple Waste Crude Extract as a Functional Feed Additive.

This study used pineapple waste crude extract (PWCE) to increase the potential of Pacific white shrimp (Litopenaeus vannamei) production for food sustainability and stability. The objective was to investigate the appropriate technique to increase the yield production and quality of shrimp and decrease waste from shrimp culture. Pacific white shrimp (average body size: 0.51 g) were fed with commercial feed supplemented with PWCE at various concentrations of 0 (control), 90, 170, and 250 ppt. Shrimp were fed five times per day for 80 days. At the end of the trial, the results showed that shrimp fed with the PWCE 250 ppt supplementation provided the highest growth rate and the best feed utilisation and yield (P < 0.05). The protein content of whole shrimp in all shrimp fed with the PWCE supplementation diet was higher than that in the control group (P < 0.05). On the contrary, the variation of endogenous digestive enzymes, including protease, trypsin, and the T/C ratio, was significantly lower in shrimp fed a diet supplemented with PWCE 250 ppt (P < 0.05). While in this group, the number of microorganisms on thiosulfate-citrate-bile salt-sucrose (TCBS), blood agar, and trypticase soy agar (TSA) was lowest (P < 0.05). Furthermore, the dietary PWCE at 250 ppt increased the volume of microvilli in the hindgut of shrimp, but the supplementation at 170 ppt improved the number of F-cells in the epithelial cells of the hepatopancreas. Nevertheless, the supplementation of PWCE in the diet did not affect the water quality (P > 0.05). Therefore, pineapple waste crude extract supplementation improves both quantitative and qualitative yields and tends to reduce waste.

The effects of replacing fishmeal by mealworm (Tenebrio molitor) on digestive enzymes activity and hepatopancreatic biochemical indices of Litopenaeus vannamei

Abstract Reducing the use of fishmeal (FM) in aquafeed means a significant saving in the amount of FM at the global level and reducing environmental impacts. One of the potential protein sources to replace FM in shrimp diet is the use of insects’ meal. Therefore, the present study aimed to examine the effects of replacing FM with mealworm (MW; Tenebrio molitor) on the growth, digestive enzymes activity and hepatopancreatic biochemical indices of Pacific white shrimp (Litopenaeus vannamei). Shrimp were fed for 60 days with a control diet (T0) and 4 practical diets (T15, T30, T60 and T100) where 15, 30, 60 and 100% of the FM was substituted by MW, respectively. Results showed that there were significant differences in weight gain (WG) and hepatopancreatic index (HPI) among treatments and the lowest and highest values were observed in T0 and T30, respectively. Our findings indicated a significant increase (P&lt;0.05) in activity of glutathione peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), total nitric oxide (TNO) and total antioxidant capacity (TAC) and a meaningful decrease (P&lt;0.05) of malondialdehyde (MDA) in hepatopancreas of L. vannamei juveniles fed diets containing MW. The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the T0 did not show a significant difference (P&gt;0.05) with other experimental treatments. Protease and lipase indicated an increasing trend with increasing the amount of MW up to 60%. The protease activity showed a significant difference (P&lt;0.05) between the treatments containing MW and the control treatment. These findings indicated that MW could be a feasible candidate for replacing FM in diets of the Pacific white shrimp without any detrimental effects.

Impacts of acute cold-stress in Pacific white shrimp Litopenaeus vannamei: investigating the tissue-specific stress resistance response

Impacts of acute cold-stress in Pacific white shrimp Litopenaeus vannamei: investigating the tissue-specific stress resistance response

Maribacter litopenaei sp. nov., isolated from the intestinal tract of the Pacific white shrimp Litopenaeus vannamei.

A Gram-stain-negative, aerobic, rod-shaped bacterial strain, designated HL-LV01T, was isolated from the intestinal tract content of the Pacific white shrimp Litopenaeus vannamei. The 16S rRNA gene sequence of strain HL-LV01T showed that the strain was clearly a member of the genus Maribacter. According to the phylogenetic analyses, strain HL-LV01T was most closely related to the species Maribacter flavus KCTC 42508T with 98.2 % sequence similarity. The average nucleotide identity and digital DNA-DNA hybridization values between strain HL-LV01T and M. flavus KCTC 42508T were 80.6 % and 23.0 %, respectively, indicating different genomic species in the genus Maribacter. Strain HL-LV01T showed optimal growth at 35 °C, pH 7.0, and 2.5 % (w/v) sea salts. The major cellular fatty acids were iso-C15 : 0 (32.5 %), iso-C17 : 0 3-OH (22.3 %), and iso-C15 : 1 G (15.5 %). The major respiratory quinone was menaquinone-6. The polar lipids consisted of phosphatidylethanolamine, three unidentified aminolipids, and seven unidentified lipids. The genomic DNA G+C content of the strain was 39.8 mol%. The comprehensive phylogenetic, genomic, phenotypic, and chemotaxonomic results indicate that strain HL-LV01T is distinct from validly published species of the genus Maribacter. Hence, we propose strain HL-LV01T as a novel species belonging to the genus Maribacter, for which the name Maribacter litopenaei sp. nov. is proposed. The type strain is HL-LV01T (= KCCM 90498T = JCM 35709T).

Gene Structure, Expression and Function Analysis of MEF2 in the Pacific White Shrimp Litopenaeus vannamei

The Pacific white shrimp Litopenaeus vannamei is the most economically important crustacean in the world. The growth and development of shrimp muscle has always been the focus of attention. Myocyte Enhancer Factor 2 (MEF2), a member of MADS transcription factor, has an essential influence on various growth and development programs, including myogenesis. In this study, based on the genome and transcriptome data of L. vannamei, the gene structure and expression profiles of MEF2 were characterized. We found that the LvMEF2 was widely expressed in various tissues, mainly in the Oka organ, brain, intestine, heart, and muscle. Moreover, LvMEF2 has a large number of splice variants, and the main forms are the mutually exclusive exon and alternative 5' splice site. The expression profiles of the LvMEF2 splice variants varied under different conditions. Interestingly, some splice variants have tissue or developmental expression specificity. After RNA interference into LvMEF2, the increment in the body length and weight decreased significantly and even caused death, suggesting that LvMEF2 can affect the growth and survival of L. vannamei. Transcriptome analysis showed that after LvMEF2 was knocked down, the protein synthesis and immune-related pathways were affected, and the associated muscle protein synthesis decreased, indicating that LvMEF2 affected muscle formation and the immune system. The results provide an important basis for future studies of the MEF2 gene and the mechanism of muscle growth and development in shrimp.

Influence of Total Suspended Solids on the Growth of the Sea Lettuce Ulva lactuca Integrated with the Pacific White Shrimp Litopenaeus vannamei in a Biofloc System

A biofloc system is rich in nutrients, which favors the cultivation of macroalgae, but the influence of the system on the performance of macroalgae is unknown. The objective of this study was to analyze the feasibility of introducing the macroalgae Ulva lactuca into the culture of Litopenaeus vannamei in a biofloc system. The first experiment evaluated the influence of 400 mg L−1 and 30 mg L−1 solids concentration of the system in biofloc and von Stosch culture medium on macroalgae growth. In the second experiment, the densities of 1, 2, and 3 g L−1 of U. lactuca were cultivated in an integrated system with shrimp and monoculture treatment. Both experiments had 35 days of cultivation. There was no significant difference in macroalgae growth between the treatments with biofloc and von Stosch culture medium. In the integrated culture, the density of 1 g L−1 showed better nutrient absorption. Shrimp performance was not affected by macroalgae cultivation. In conclusion, the solids did not affect the growth of the macroalgae, and it could be cultivated in a biofloc system for nitrate uptake in integrated culture with shrimp.

Effects of Sulfamethoxazole and Florfenicol on Growth, Antioxidant Capacity, Immune Responses and Intestinal Microbiota in Pacific White Shrimp Litopenaeus vannamei at Low Salinity.

Antibiotic residue may pose a serious risk to aquaculture, and the culture of Litopenaeus vannamei in a low-salinity environment is a growing trend over the world. Here, we aimed to understand the combined effect of low salinity and sulfamethoxazole (SMZ) and florfenicol (FLO) antibiotics on L. vannamei. The growth performance, immune functions, antioxidant capacity and intestinal microbiota were investigated. Compared with the control group, the weight gain and survival rate significantly decreased (p < 0.05) in shrimp after they were exposed to low-salinity (salinity 3) water and the mixture of antibiotics and low-salt conditions for 28 days. The antioxidant activities of SOD and T-AOC, shown at low salinity and in the higher concentration of the SMZ treatment group (SMZH), were significantly decreased, while the GST activity was significantly increased in each treatment group in comparison with the control group. The expression of immune-related genes, including TOLL, LvIMD, PPO and HSP, in the low concentration of the SMZ treatment group (SMZL) was higher than that in the other groups. The diversity of intestine microbiota was disturbed with a lower Shannon index in the low-salinity and SMZH groups, and a higher Simpson index in the SMZH group. Proteobacteria, Actinobacteria and Bacteroidetes were the dominant phyla in the gut of L. vannamei. At the genus level, Microbacterium, Shewanella, Aeromonas, Acinetobacter, Gemmobacter, Paracoccus and Lysobacter were significantly decreased in the low-salinity group. However, the abundance of opportunistic pathogens belonging to the genus Aeromonas in the FLO group was increased. The predicted microbe-mediated functions showed that the pathway for "amino acid metabolism" and "replication and repair" was significantly inhibited in both the low-salinity and antibiotic-exposed groups. All the findings in this study indicate that the combined effect of antibiotics and low salinity on L. vannamei negatively impacted the physiological and intestinal microbiota functions.

Cyclin-dependent Kinase 1 (CDK1) in Pacific white shrimp (Litopenaeus vannamei): Molecular characterization and its role in response to cold stress

Cyclin-dependent kinases (CDKs) are a large family of proteins exerting different regulatory functions in eukaryotic cells, including control over the cell cycle and gene transcription. CDK1 controls the cell cycle and promotes cell proliferation by regulating the initiation and transition of the G2/M phase. Similar to mammals, CDK1 has also been characterized in arthropods; however, its functions and physiological importance in crustaceans remain unknown. Our pervious transcriptomic data indicated that CDK1 was a candidate cold-stress response gene in the Pacific white shrimp (Litopenaeus vannamei). Therefore, in the present study, the full-length sequence of CDK1 (LvCDK1) was obtained from L. vannamei containing a conserved PSTAIRE sequence and ATP-binding region. The expression of LvCDK1 is tissue-specific, with relatively higher in the hepatopancreas. The in situ hybridization (ISH) signals for LvCDK1 were present in the distal zone of hepatopancreas and mainly located in the cytoplasm and nucleus. The expression of LvCDK1 in hepatopancreatic was sensitive to environmental temperature. Furthermore, under cold stress, knockdown of LvCDK1 led to increased mortality in shrimp. Our study provides the first evidence of LvCDK1 responding to cold stress in shrimps. This mechanism for modifying the transcriptional roles of LvCDK1 may show new light on the molecular regulation of crustaceans in response to cold stress.

Investigating active packaging based on cellulose nanofibers oxidized by TEMPO method containing hydrolyzed protein obtained from pine tree fruit on the quality of pacific white shrimp (Litopenaeus vannamei) during the storage period

Investigating active packaging based on cellulose nanofibers oxidized by TEMPO method containing hydrolyzed protein obtained from pine tree fruit on the quality of pacific white shrimp (Litopenaeus vannamei) during the storage period

The effects of replacing fishmeal by mealworm (Tenebrio molitor) on digestive enzymes activity and hepatopancreatic biochemical indices of Litopenaeus vannamei

Abstract Reducing the use of fishmeal (FM) in aquafeed means a significant saving in the amount of FM at the global level and reducing environmental impacts. One of the potential protein sources to replace FM in shrimp diet is the use of insects’ meal. Therefore, the present study aimed to examine the effects of replacing FM with mealworm (MW; Tenebrio molitor) on the growth, digestive enzymes activity and hepatopancreatic biochemical indices of Pacific white shrimp (Litopenaeus vannamei). Shrimp were fed for 60 days with a control diet (T0) and 4 practical diets (T15, T30, T60 and T100) where 15, 30, 60 and 100% of the FM was substituted by MW, respectively. Results showed that there were significant differences in weight gain (WG) and hepatopancreatic index (HPI) among treatments and the lowest and highest values for were observed in T0 and T30, respectively. Our findings indicated a significant increase (P&lt;0.05) in activity of glutathione peroxidase (GPX), catalase (CAT), superoxide dismutase (SOD), total nitric oxide (TNO) and total antioxidant capacity (TAC) and a meaningful decrease (P&lt;0.05) of malondialdehyde (MDA) in hepatopancreas of L. vannamei juveniles fed diets containing MW. The alanine aminotransferase (ALT) and aspartate aminotransferase (AST) in the T0 did not show a significant difference (P&gt;0.05) with other experimental treatments. Protease and lipase indicated an increasing trend with increasing the amount of MW up to 60%. The protease activity showed a significant difference (P&lt;0.05) between the treatments containing MW and the control treatment. These findings indicated that MW could be a feasible candidate for replacing FM in diets of the Pacific white shrimp without any detrimental effects.

Relationship between aerobic scope and upper thermal limits of Pacific white shrimp (Litopenaeus vannamei) in low-salinity culture systems

Aquaculture of the Pacific white shrimp Litopenaeus vannamei in low-salinity water is a viable industry and production strategy in the southeastern United States. A major challenge facing this industry is a phenomenon called late-term mortality which is thought to be driven by thermal stress at the end of the growing season when water temperatures can reach or exceed 36 °C in shrimp production ponds. To investigate the physiological mechanisms behind upper lethal limits in shrimp, we evaluated linkages between empirically measured thermal limits and absolute aerobic scope (AAS), or ability to provide energy above that needed for basic maintenance. In this study, we tested whether thermal tolerance decreases with increasing shrimp age/size and whether AAS is a useful concept for understanding the physiological basis of thermal tolerance in shrimp. We exposed two size classes (small: 2.07 ± 0.86 and large: 24.64 ± 2.55 g) of shrimp to increasing temperature at a rate of 1 °C/h from 28 to 42 °C. At each temperature, we used intermittent respirometry to estimate resting metabolic rate and we directly measured lethal thermal tolerance by evaluating critical thermal maximum (CTmax). Additionally, we used the electron transport system assay to estimate maximum metabolic rate (RMR) at temperatures from 9 to 45 °C. Small shrimp had a higher CTmax than large shrimp, with upper lethal limits of 40.6 and 39.0 °C, respectively. For both size-classes, AAS reached its minimum (AASmin) at temperatures near the peak RMR (RMRpeak) and within 2 °C of CTmax. Large shrimp exhibited a lower temperature at AASmin than that of the smaller shrimp. Reductions in AAS appear to be one of the underlying physiological drivers of thermal tolerance in L. vannamei and an indicator of increasing thermal stress. Changes in the temperature at which AAS reaches its minimum may be a useful predictor of shifts in thermal tolerance among shrimp size-classes.

Metabolic turnover rate, digestive enzyme activities, and bacterial communities in the white shrimp Litopenaeus vannamei under compensatory growth.

The present work aimed to evaluate the effects promoted by a phase of compensatory growth on metabolic turnover rate, digestive enzyme activity, and bacterial biota of the Pacific white shrimp Litopenaeus vannamei kept under different feeding regimes. Three treatments were evaluated as follows: 70% feed restriction during 3 (T3) and 6 (T6) days, followed by a period of feeding to satiety, and a control treatment without restriction periods. The results showed a full compensatory growth in treatments T3 and T6 by day 35 of the bioassay. A significant increase in trypsin and lipase (T6) activities was observed during compensatory growth, whereas specific amylase activity was significantly lower in treatment T6 compared to T3 but not significantly different from the control group. To determine the metabolic turnover rate of nitrogen in muscle tissue, an analysis of nitrogen isotope values (δ15N) at natural abundance levels was performed. At the end of the experimental period, shrimp under feed restriction had lower metabolic turnover rates and longer nitrogen residence times (t 50) in muscle tissue, as compared to individuals in the control treatment. Regarding the changes in the bacterial communities in shrimp gut, no significant differences were observed at the phylum level, with Proteobacteria being the most abundant bacteria, followed by Actinobacteria. At family taxa level, Rhodobacteraceae presented the highest relative abundance in all treatments, whereas a decrease in Vibrionaceae was observed in treatments T3 and T6 when compared to control shrimps during compensatory growth. At the genus level, a decrease in Celeribacter, Catenococcus, and Epibacterium, and an increase in Ruegeria and Shimia, were identified in shrimp subjected to feed restriction when compared to control organisms during compensatory growth (day 14). At the end of the experimental period, the evaluated parameters showed similar results as those observed in the control treatment, suggesting a normalization of the metabolism and the physiological state. The present findings contribute to a better understanding on the physiological effects produced during compensatory growth in shrimp, which in turn could assist in the development of improved feeding strategies in benefit of the aquaculture industry.

Effects of feed, carbohydrate addition and stocking density on Pacific white shrimp (Litopenaeus vannamei) production

Shrimp culture rearing systems are dynamic with numerous processes influencing system performance. This research investigated the effects of stocking density, feeding level and C:N ratio on shrimp production, water quality and microbial community composition in a biofloc shrimp rearing system, using a 3 × 3 factorial design. Pacific white shrimp (Litopenaeus vannamei) were stocked at 27, 120, or 300 individual m−3 and fed 100, 80 or 60% of the recommended daily feed ration. For each combination of stocking density and feeding level, C:N ratios of 7.4, 12 or 16 were created by feeding a mixture of casava and rice bran besides the daily pelleted feed input to culture tanks. After 12 weeks of culture, the harvested shrimp biomass was the highest in the rearing tanks with the highest stocking density, feeding level and C:N ratio (P < 0.05), while the individual shrimp size at harvest decreased with increasing stocking density (P < 0.05). Biofloc biomass (e.g. total suspended solids TSS, volatile suspended solids VSS) and, to a lesser degree, water quality (total ammonia nitrogen TAN, NO2-N) were affected by 2 and 3-way interactions of the main tested factors. The ash, protein, fat and nitrogen free extract (NFE) content in biofloc were affected by stocking density (P < 0.05), and ash and NFE content by C:N ratio (P < 0.05). Regarding the microbial community composition in the biofloc at the highest stocking density, increasing feeding level and C:N ratio led to an increasing microbial richness and diversity (P < 0.05) as a result of nutrient input. Overall, the shrimp production and biofloc biomass were influenced in a similar way by the stocking density, feeding level and C:N ratio applied in the biofloc system. Future research should focus on how the type of carbohydrates and methods of administration affect shrimp growth and biofloc formation, and how this may promote health benefits through the microbial community manipulation.

Potential Symbiotic Effects of β-1,3 Glucan, and Fructooligosaccharides on the Growth Performance, Immune Response, Redox Status, and Resistance of Pacific White Shrimp, Litopenaeus vannamei to Fusarium solani Infection

The potential effects of dietary supplementation with β-1,3 glucan and fructooligosaccharides (β-1,3 GF) on antioxidant activities, immunological response, and growth performance of Pacific white shrimp (Litopenaeus vannamei) was investigated. Four diets (iso-energetic and iso-nitrogenous) with different levels of β-1,3 GF (0, 0.5, 1.0, and 1.5 g kg−1) were fed to healthy shrimp juveniles weighing 3 ± 0.5 g for 75 days. Shrimps were randomly distributed into 12 net enclosures at a density of 30 shrimp/net, and the experiment was performed in triplicate. The results revealed that long-term supplementation with 1.5 g kg−1 β-1,3 GF significantly improved shrimp weight gain, feed conversion ratio, and digestive enzyme profiles compared to the control diet group. However, there were no substantial variations in the contents of moisture, crude protein, total lipids, and ash in the muscles of shrimp fed on different diets. Surprisingly, all antioxidants (superoxide dismutase, catalase, glutathione peroxidase) and immune biomarkers (lysozyme, total hemocyte count, phenol oxidase, and respiratory burst) activities were significantly elevated with increasing levels of β-1,3 GF in the shrimp diet, and the highest values were recorded in the 1.5 g kg−1 diet groups. Challenge test results revealed that F. solani could cause a high mortality rate (86.7%) in a group fed a normal basal diet within 14 days at a dose of 5 × 104 conidia mL−1. Surprisingly, all dietary treated groups with different doses of β-1,3 GF showed high resistance against F. solani, represented by lower cumulative mortality rates (20–43.3%) compared to the control group. Moreover, most of the infected shrimp showed a typical black to brown gill lesion similar to that observed in the natural infection, where an identical fungus was successfully re-isolated from infected gills and muscles. Overall, this study recommends an appropriate incorporation level of β-1,3 GF that could enhance growth performance and improve the antioxidant activities, non-specific immunity, and disease resistance of L. vannamei, with an optimal level of 1.5 g kg−1.

The effects of dietary myo-inositol on growth and physiological, biochemical, and molecular responses in the Pacific white shrimp Litopenaeus vannamei

Myo-inositol serves as an essential nutrient in many animal species. However, the optimal requirements of myo-inositol and the mechanisms by which myo-inositol is involved in nutritional regulation in crustaceans are unclear. An 8-week trial was conducted to comparatively evaluate the effects of 6 levels of dietary myo-inositol (20, 528, 1030, 2060, 3180 and 4235 mg/kg diet) on growth performance, body composition, serum metabolite composition, hepatopancreatic metabolite content, and digestive enzyme activity in juvenile Pacific white shrimp Litopenaeus vannamei (0.78 ± 0.039 g). The weight gain and conditioning factors of shrimp fed myo-inositol were significantly higher than those of the 20 mg/kg myo-inositol group. The maximal hepatosomatic index was found in the 1030 mg/kg myo-inositol group. On the other hand, serum triglyceride, total cholesterol, and low-density lipoprotein contents in the control group were significantly lower than those in the other groups, and glucose content in the hepatopancreas in the control group was significantly lower than that in the 2060 and 3180 mg/kg myo-inositol groups. Metabolome and transcriptome analyses revealed that myo-inositol significantly affected glycerophospholipid metabolism, transport and catabolism in lysosomes, pancreatic secretion, and bile secretion pathways. The highest growth was achieved with the inclusion of 528 mg/kg dietary myo-inositol. This study has suggested that myo-inositol may promote growth in L. vannamei by improving lipid utilization.

5-Aminolaevulinic acid reduced the mortality of the Pacific white shrimp Litopenaeus vannamei infected with Enterocytozoon hepatopenaei

Hepatopancreatic microsporidiosis, the shrimp disease caused by Enterocytozoon hepatopenaei (EHP) infection, has been widely spread in farmed Litopenaeus vannamei in Thailand. The symptoms include decreased feeding, muscle waste, slow growth, and chronic mortality. Since 5-aminolaevulinic acid (5-ALA), a non-protein amino acid, has been known to enhance ATP production in the cell through the increased formation of hemoproteins in the electron transport complex of mitochondria, it was hypothesized that providing 5-ALA to EHP-infected shrimp might reduce the mortality caused by the infection. Naturally EHP-infected L. vannamei were randomly sampled from a commercial shrimp pond that showed signs of hepatopancreatic microsporidiosis. The shrimp samples were reared under 30-ppt seawater in 40-L plastic tanks, divided into four groups; each receiving commercial pellets supplemented with different doses of 5-ALA: 0 (control), 15, 30, and 60 ppm. After 21 days of the experiment, it was found that the shrimp receiving 5-ALA at 60 ppm survived at a rate significantly (p < 0.05) higher than that of other groups, and had a significant increase in biomass, compared with that of the control group. Histology of the hepatopancreas of the 60-ppm group revealed significantly (p < 0.01) less percentage of atrophic tubules and larger areas of the vacuoles of the B-cells, suggesting improved hepatopancreatic functions. The levels of the EHP load in the hepatopancreas as revealed by semi-quantitative PCR were increasing in a dose-related manner of 5-ALA supplement. Histology of the hepatopancreas also revealed the presence of EHP. The ATP levels in the hepatopancreas of the 30- and 60-ppm groups were significantly (p < 0.01) higher than that of the control group. Further tests are required in commercial farms to find out if the 5-ALA supplement is beneficial to tackle the problem of hepatopancreatic microsporidiosis at the industrial level.

Production of pacific white shrimp in biofloc system with different food management strategies

In the present work, different models for adjustments in feeding rates to produce Pacific white shrimp (Litopenaeus vannamei) in a biofloc system were analyzed. Shrimps were stocked with an initial weight of 4.21 ± 0.09 g at a density of 250 shrimp m-3 and fed following different methodologies for 60 days. The first method was according to the Van-Wyk table, considering the minimum (MIN) and maximum (MAX) feed rates. The second was according to two estimated values from the feed conversion ratio (FCR; FCR of 1.1 and 1.5), based on the methodology determined by Garzade Yta. A completely randomized experimental design was adopted, consisting of four treatments (MAX, MIN, FCR 1.1, and FCR 1.5) with 4 independent replicates. Zootechnical performance, the physical and chemical water quality parameters, and the production of solids in the system were evaluated. The treatment that used minimum amounts of feed determined by the table showed a better feed conversion, survival, using a lower amount of feed and, thus, generating less waste. Although the feeding strategy using the minimum values in the table has shown better results, it is still necessary to improve these strategies, as the Biofloc system is a system that has variations and their adjustments must be made according to the interactions of the system.

The effects of stocking density and artifical substrate on production of pacific white shrimp Litopenaeus vannamei and water quality dynamics in greenhouse-based biofloc systems

Inland shrimp aquaculture has increased in popularity in recent years as a means of providing fresh seafood to consumers away from the coasts. With adequate marketing,fresh shrimp fetch relatively high prices and can give farmers a means of diversifying, production. In temperate regions such as Kentucky, low-cost high tunnel greenhouses may be used to extend the growing season of warm-weather crops, including tropical animals such as penaeid shrimp. To optimize investments, inland producers are constantly exploring methods to increase overall production. A 100 day-long study examined the effects of stocking density and artificial substrates on water quality, stable isotope dynamics, and production of Litopenaeus vannamei using biofloc-based aquaculture systems in greenhouses. Four treatments were compared: High Density Substrate (HD/S), High Density No-Substrate (HD/NS), Low, Density Substrate (LD/S), and Low Density No-Substrate (LD/NS). Four high tunnel greenhouses each contained four 10.9 m3 tanks. The experiment was blocked by location such that one replicate from each treatment was randomly assigned within each greenhouse to account for potential environmental variation. Each tank was outfitted with a settling chamber for solids filtration, and 13.1 m2 of polypropylene, construction safety fencing was used as substrate in the substrate-containing tanks. Shrimp were stocked into the experimental systems at 2.71 g mean weight; high density treatments were stocked with 300 shrimp/m3, while low density treatments were stocked with 200 shrimp/m3. Water temperatures were significantly lower over the course of the entire study within substrate treatments. pH throughout the study was significantly lower within substrate treatments and high density treatments. Stable isotope data indicated that very little of the carbon and nitrogen in shrimp tissues was likely sourced from biofloc and periphyton material. Low density treatments had significantly lower FCRs than high density treatments. However, the addition of substrate in the HD/S treatment resulted in significantly more efficient shrimp FCR than was observed in the HD/NS treatment. The HD/S treatment also had significantly higher, shrimp biomass than all other treatments. High density treatments had significantly higher FCR and lower survival than low density treatments. This study demonstrates that artificial substrates can reduce some of the negative effects of high shrimp stocking density, with significant improvements in FCR and biomass production. Although it is important to note the implications for water quality, adding substrate to facilitate high density shrimp culture in high tunnel greenhouses can facilitate higher stocking density without compromising the size of the animals

Comparative study on the effects of crystalline L-methionine and methionine hydroxy analogue calcium supplementations in the diet of juvenile Pacific white shrimp (Litopenaeus vannamei).

An 8-week feeding trial was conducted to evaluate the effects of L-methionine and methionine hydroxy analogue calcium (MHA-Ca) supplements in low-fishmeal diet on growth performance, hepatopancreas morphology, protein metabolism, anti-oxidative capacity, and immunity of Pacific white shrimp (Litopena eus vannamei). Four isonitrogenous and isoenergetic diets were designed: PC (203.3g/kg fishmeal), NC (100g/kg fishmeal), MET (100g/kg fishmeal +3g/kg L-methionine) and MHA-Ca (100g/kg fishmeal +3g/kg MHA-Ca). White shrimp (initial body weight 0.23 ± 0.00 g, 50 shrimp per tank) were allocated to 12 tanks and divided among 4 treatments in triplicates. In response to L-methionine and MHA-Ca supplementations, the shrimp exhibited higher weight gain rate (WGR), specific growth rate (SGR), condition factor (CF), and lower hepatosomatic index (HSI) compared to those fed the NC diet (p < 0.05). The WGR and SGR of shrimp fed L-methionine and MHA-Ca showed no difference with those in the PC diet (p > 0.05). Both of L-methionine and MHA-Ca supplementary diets significantly decreased the malondialdehyde (MDA) levels of shrimp when compared with the NC diet (p < 0.05). L-methionine supplementation improved the lysozyme (LZM) activity and total antioxidant capacity (T-AOC) of shrimp, while the MHA-Ca addition elevated the reduced glutathione (GSH) levels in comparison with those fed the NC diet (p < 0.05). Hypertrophied blister cells in hepatocytes were observed in shrimp fed the NC diet, and alleviated with L-methionine and MHA-Ca supplementations. Shrimp fed the MET and MHA-Ca diets had higher mRNA expression levels of target of rapamycin (tor) than those fed the NC diet (p < 0.05). Compared to the NC group, dietary MHA-Ca supplementation upregulated the expression level of cysteine dioxygenase (cdo) (p < 0.05), while L-methionine supplementation had no significant impact (p > 0.05). The expression levels of superoxide dismutase (sod) and glutathione peroxidase (gpx) were significantly upregulated by L-methionine supplemented diet in comparison with those in the NC group (p < 0.05). Overall, the addition of both L-methionine and MHA-Ca elevated the growth performance, facilitated protein synthesis, and ameliorated hepatopancreatic damage induced by plant-protein enriched diet in L. vannamei. L-methionine and MHA-Ca supplements enhanced anti-oxidants differently.

Dietary effects of cottonseed protein concentrate substituting fishmeal on the growth and flesh quality of Pacific white shrimp (Litopenaeus vannamei)

The present study aimed to investigate the dietary effects of replacing fishmeal (FM) with cottonseed protein concentrate (CPC) on the growth, flesh quality and gossypol residue of Pacific white shrimp (Litopenaeus vannamei). Based on a diet containing 560 g/kg FM, CPC was used to replace 0%, 20%, 40%, 60%, 80% and 100% of dietary FM with CPC inclusion of 0, 130.2, 260.4, 390.7, 521 and 651.3 g/kg, respectively (CPC0, CPC20, CPC40, CPC60, CPC80 and CPC100). Then, the six isoproteic diets were used to feed shrimp with initial body weight of 1.20 ± 0.05 g in low salinity water (0.5–1.0‰) for 56 days. The results showed that the growth performance of shrimp was not significantly affected by the replacement of 20%, 40% of dietary FM with CPC (P > 0.05). Compared to the control, the weight gain was decreased by 15.1%, 21.7% and 33.8% (P < 0.05), while feed conversion ratio was increased by 0.15 (P > 0.05), 0.18（P < 0.05）and 0.23 (P < 0.05) in CPC60, CPC80 and CPC100 groups, and the meat yield were also significantly decreased in the three groups. Flesh water holding capacity, hardness, chewiness, SOD activity, free flavor amino acid and heat insoluble collagen contents of CPC80 and CPC100 groups were significantly lower, while flesh MDA content was significantly higher than those of the control group. There were no significant differences in flesh proximate composition, amino acid composition and free gossypol content among all the groups. In conclusion, in a diet containing 560 g/kg FM, CPC could successfully substitute 40% of dietary FM, and higher substitution decreased the growth performance and flesh quality of Pacific white shrimp.