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A preliminary study was conducted to demonstrate fate of the bacterial storage compound poly-beta-hydroxybutyrate (PHB) once ingested and degraded in vivo in crustaceans. The 2% supplementation of C-13-labeled Ralstonia eutropha DSM545 containing 75% PHB on dry weight in postlarval whiteleg shrimp, Litopenaeus vannamei resulted in consistent enrichment of two fatty acids (containing 14-24 carbons [C] in length) pentadecanoic acid (15:0) and palmitic acid (16:0) in all lipid fractions. This could indicate that C-13 signal may not only originate from the PHB but partly from the structural components of the bacterial cell. There was a trend of lower C-13 enrichment in various lipid fractions of the postlarvae as compared to the diet. These findings may have important implications as to potential of PHB as energy source rather than as building block. There was a rapid transfer of C-13 in the postlarvae as seen by the significant C-13 enrichment in the tissues 4 hr after feeding with labeled bacterial cells. Overall, the assimilation of PHB in crustacean tissues is demonstrated for the first time. Our results indicate that PHB once ingested is rapidly assimilated in the tissues and could probably act as an energy source rather than as a building block.

Heritability and genetic correlations for body weight at harvest size (BW), grow‐out survival (SU), and log‐transformed infectious hypodermal and hematopoietic necrosis virus (IHHNV) load (VLₗₙ) in Litopenaeus vannamei were estimated. Data were obtained in 2012 from a shrimp breeding population in Mexico using 12,440 shrimp for BW and 16,814 shrimp for SU, and quantitative polymerase chain reaction determinations from 160 full‐sib families were obtained for VLₗₙ. DNA was extracted from pooled muscle samples of six shrimp per family for a total of 960 individuals. Heritability estimates for BW, SU, and VLₗₙ at the family mean and at individual levels were 0.24 ± 0.08, 0.02 ± 0.01, 0.42 ± 0.45, and 0.08 ± 0.11, respectively. Genetic correlation estimates of BW with SU, BW with VLₗₙ, and VLₗₙ with SU were 0.40, −0.04, and −0.57, respectively. Our results suggest that VLₗₙ has genetic variation and a favorable genetic association with BW and SU. No serious drawbacks were found from selection responses estimated using single‐trait and multitrait indices to increase BW and SU and decrease VLₗₙ. Favorable correlated responses for IHHNV tolerance estimated as BW/VLₗₙ and SU/VLₗₙ were also found. This study offers new insights into the possibility of using IHHNV viral load as a possible selection criterion in L. vannamei breeding programs.

The phenotypic characteristics and growth kinetics at several temperatures, salinities, and pH values of three Vibrio parahaemolyticus (Vp) strains with different virulence and one nonpathogenic strain were evaluated. Independent of the virulence of the strain, a high metabolic diversity was found, which yielded different colored phenotypes on the CHROMagar™ Vibrio. All strains were resistant to ampicillin and carbenicillin, and Vp AHPND+ organisms were the most sensitive to enrofloxacin. The exponential growth of Vp strains started at 1–2 hr of incubation, although no relationship was observed between the bacterial density and degree of virulence. Moreover, the growth of the most virulent strain was independent of the nutrients in the incubation media during the initial hour postinoculation. No strain grew at 4°C in 0% NaCl and pH 4, but only Vp AHPND+ grew at 44°C. For all strains, the lag phase was proportional to the NaCl concentration, and the growth was better at pH 8–9. However, the Vp AHPND− strain displayed a greater variability, was more sensitive to extreme conditions, and showed a lag phase of 9 hr independent of the pH.

Squid visceral paste is a popular attractant and feeding stimulator supplement in shrimp feeds in China, but it often faces problems with fluctuating availability, cost, composition, and quality. An 8‐week experiment was performed to test a proprietary palatability enhancer as an alternative to squid paste in white shrimp feed. Seven diets were tested: a control diet with no supplementations; S1 and S3 diets supplemented with squid paste at 1 or 3%, respectively; S1+PE0.1 and S1+PE0.15 supplemented with both 1% squid paste and the palatability enhancer at either 0.1 or 0.15%, respectively; and finally PE0.1 and PE0.15 supplemented only with the palatability enhancer at 0.1 or 0.15%, respectively. The results showed a trend for increased feed intake and weight gain when squid paste was added to the diet compared to the control, but this was worsened by raising the inclusion level from 1 to 3%. The inclusion of the PE, in combination with squid paste or alone at 0.15%, led to a significantly higher growth, and a feeding stimulation effect was also indicated, with PE0.1 and PE0.15 having a higher feed intake than the control. A further beneficial effect was a significant increase in protease activity in the hepatopancreas in the S1+PE0.15, PE0.1, and PE0.15 treatments compared to the control. In addition, a significant increase in the height of the intestinal mucosal folds was observed in PE0.15, followed by PE0.1. The results demonstrated the potential to replace or reduce squid visceral paste in shrimp diets by supplementing with a PE with functional effects beyond feeding stimulation.

The use of supplemental essential amino acids (EAAs) has been shown to provide an opportunity to minimize excess levels of crude protein (CP) in animal feeds. The present study investigated the effect of reducing the amount of CP in low‐fish meal diets (5%) for juvenile Litopenaeus vannamei. Four sets of diets were prepared containing (% on a fed basis, mean ± SD) 31.24 ± 0.71, 33.70 ± 0.41, 36.90 ± 0.44, and 39.63 ± 0.14% CP, with each protein level containing a total dietary methionine (Met) (Met + Cys) level of 0.56 ± 0.02 (1.07 ± 0.23), 0.71 ± 0.01 (1.22 ± 0.20), 0.88 ± 0.02 (1.38 ± 0.22), or 1.04 ± 0.02% (1.55 ± 0.18%). Shrimp of 1.00 ± 0.08 g were stocked in 84 outdoor tanks of 1 m³ at a rate of 100 shrimp/m² and raised for 75 days. Final survival ranged from 83 to 97% and was unaffected by Met content. Both survival and yield were significantly depressed when shrimp were fed the 31% CP diet. Shrimp grew at a weekly rate of between 0.79 and 0.97 g, achieving a final body weight (BW) in excess of 10.8 g. There was a significant interaction between CP and Met over BW. Shrimp fed 0.56% Met achieved the lowest BW at harvest. Increasing CP beyond 34% did not enhance BW. With a dietary Met content of 0.71%, the highest BW was achieved with 34% CP compared to other levels. There was a significant improvement in Feed Conversion Ratio (FCR) when CP was raised from 31 to 34%. Similarly, dietary Met levels above 0.71% resulted in a significantly better FCR compared to 0.56%. Our study has shown that, if dietary Met (Met + Cys) meets a minimum of 0.71% (1.22%), levels of CP could be reduced from 40 to 34% without adverse effects on shrimp performance.

An 8‐week growth trial was conducted to evaluate the use of a high protein distiller's dried grain (HPDDG, NexPro®, Flint Hills Resources, LP, Wichita, KS) on the growth performance of juvenile Pacific white shrimp Litopenaeus vannamei. In the growth trial, graded levels of HPDDG (0.00, 10.00, 15.00, and 20.00%) were used to replace corn protein concentrate (CPC: 12.60, 6.30, 3.15, and 0.00%) or fishmeal (FM: 17.40, 9.79, 6.00, and 2.21%). A commercially produced open‐feed formulation was also included in the trial as a reference. Each diet was randomly assigned to four replicate groups of 30 shrimp stocked in 0.8 m³ culture tanks. Under green water conditions, in the presence of natural foods, the results indicated that growth performance and feed conversion ratio were not statistically influenced by increasing levels of HPDDG when used to replace CPC. The FM replacement series trial results showed that shrimp fed a diet with 20% HPDDG exhibited significantly decreased trend of biomass. Results of this study demonstrate that HPDDG is a good protein source, and 20% HPDDG can be used to replace CPC in shrimp diets, or up to 15% when replacing FM.

To investigate the feasibility of using micro‐organisms for ammonia‐N removal, six strains were isolated from Chinese white shrimp, Fenneropenaeus chinensis, seawater culture ponds in Dongying (Shandong, China). Of these, strain DY‐01, which exhibited the highest capacity to degrade ammonia‐N, removed 61.7% of the total ammonia‐N (50 mg/L) in 8 hr. An investigation of the factors affecting the removal efficiency indicated the optimum conditions to be 30°C, pH 8.0, and a salinity level of 30 g/L; 16S rDNA gene sequencing and biochemical analysis identified strain DY‐01 as Cobetia amphilecti, which has not previously been reported to degrade ammonia‐N. This strain also boosted the growth of Pacific white shrimp, Litopenaeus vannamei (p

The purpose of this study was to examine the effects of four feed‐management techniques on the production of Pacific white shrimp, Litopenaeus vannamei, using a 16‐wk trial performed in 16, 0.1‐ha ponds stocked at 17 shrimp/m². Four treatments were used for this study: standard feeding protocol (SFP) fed twice daily, a 15% increase to the SFP fed twice daily, timer feeders programmed to feed six times daily following the SFP, and ad libitum using the AQ1 acoustic demand feeding system. Significant increases in final weights were seen using the timer and acoustic feeders (28.66 and 35.91 g, respectively) when compared with the SFP and SFP + 15% (23.55 and 24.65 g, respectively). The AQ1 treatment also resulted in a significantly higher shrimp value ($21,198/ha) than the other treatments ($11,776–$13,446/ha). No significant differences were seen in survival (72.2 ± 5.99%), feed conversion ratio (1.03 ± 0.095), or water quality. These results demonstrate that increasing the feed by 15% when feeding twice daily gives no advantage to production. Increasing the feedings from two to six times per day did improve growth and economic returns, and using acoustic feedback to feed based on feeding activity can further improve production and economic returns.

The efficacy of hot‐water extract of tropical brown seaweed, Sargassum cristaefolium (SCE), supplemented in diets on immune response, stress tolerance, and disease resistance of Litopenaeus vannamei to Vibrio parahaemolyticus was evaluated. Shrimp were fed diets containing graded levels of SCE (0, 250, 500, 750, and 1000 mg/kg). The results showed that shrimp fed all diets containing SCE had significantly higher (P

Shrimp farms in India had average yields (pond surface basis) of 7.86 ± 1.04 (SE) m.t./ha/yr for Litopenaeus vannamei (n = 89) and 3.88 m.t./ha/yr for Penaeus monodon (n = 11). Average feed conversion ratio was 1.48 ± 0.04 for L. vannamei and 1.24 ± 0.12 for P. monodon. Land use for production ponds, supporting area, and feed ingredients averaged 0.634 ± 0.053 ha/m.t. for L. vannamei and 0.716 ± 0.087 ha/m.t. for P. monodon. Saline water volume used at farms without water exchange was 18,522 ± 4065 m³/m.t. for L. vannamei and 9528 m³/m.t. for P. monodon. Farms exchanging water used 149,188 m³/m.t. for L. vannamei and 191,500 m³/m.t. for P. monodon. Freshwater embodied in feed was 1678 ± 508 m³/m.t. for L. vannamei and 1401 ± 137 m³/m.t. for P. monodon. Average energy use for farm construction and repair, farm operations, and embodied in feed and liming materials was 82.14 ± 9.08 GJ/m.t. for L. vannamei and 59.03 ± 24.92 GJ/m.t. for P. monodon. Wildfish used to make fishmeal included in feed was 1209 kg/m.t. for L. vannamei and 1611 kg/m.t. for P. monodon. Farm infrastructure, pond management methods, yields, and resource use in India were similar to those previously reported for shrimp farms in Thailand and Vietnam.

Resource use was investigated at 34 Litopenaeus vannamei and five Penaeus monodon farms in Thailand and 30 L. vannamei and 24 P. monodon farms in Vietnam. Farms varied in water surface areas for production, reservoirs, canals, and settling basins; in pond size and depth; and in water management, stocking density, feeding rate, amendment input, aeration rate, crop duration, and crops per year. Production of L. vannamei averaged 17.3 and 10.9 m.t./ha/yr, and feed conversion ratio averaged 1.49 and 1.33 in Thailand and Vietnam, respectively. On average, production of 1 m.t. of L. vannamei required 0.58 ha land, 5,400 m3 water, 60 GJ energy, and 1218 kg wildfish in Thailand and 1.76 ha land, 15,100 m3 water, 33.7 GJ energy, and 1264 kg wildfish in Vietnam. Resource use per metric ton of shrimp declined with greater production intensity. In Thailand, P. monodon was produced at 0.2–0.4 m.t./ha/yr, with no inputs but water and postlarvae. In Vietnam, P. monodon production averaged 3.60 m.t./ha/yr. Production of 1 m.t. of P. monodon required 0.80 ha land, 36,000 m3 water, 47.8 GJ energy, and 1180 kg wildfish, and resource use per ton production declined with increasing production intensity.

This study aimed to evaluate the effects of dietary supplementation with sodium butyrate or polyhydroxybutyrate (PHB) on growth performance, as well as changes in intestinal microbiota and hemato‐immunological parameters, of Litopenaeus vannamei reared under a superintensive biofloc system. Twelve 800‐L tanks were each stocked with 250 shrimp/m³ (3.96 ± 0.04 g mean initial weight) and reared over a 6‐wk period. The basal diet and two test diets supplemented with 2% of each feed additive. At the conclusion of the growth trial shrimp fed with the butyrate‐supplemented diet, as compared with the control shrimp, showed higher survival and productivity and lower total bacterial and Thiosulfate‐citrate‐bile salts‐sucrose Agar (TCBS) counts in the intestine. However, no differences were observed in other performance parameters analyzed. Shrimp fed with both supplementation regimens also showed an increase in total and granular hemocytes, as well as an increase in serum agglutination titer. Shrimp offered diets supplemented with sodium butyrate had higher counts of hyaline cells. Thus, for L. vannamei reared in a superintensive biofloc system, it can be concluded that dietary supplementation of sodium butyrate, more so than PHB, acted as an immune system modulator by reducing the concentration of pathogenic bacteria in shrimp gut, thereby increasing survival and productivity.

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

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

Grain distillers dried yeast (GDDY) is a yeast-based protein source that is obtained from the bioethanol industry. A range of yeast-based products has been evaluated as nutritional supplements in fish diets, yet there is limited information in shrimp. Therefore, the objective of this study was to evaluate the production response of Litopenaeus vannamei fed diets containing increasing levels of GDDY in two growth trials. In trial 1, five diets formulated to contain 360 g/kg crude protein, 80 g/kg lipids, and up to 300 g GDDY/kg were evaluated under laboratory conditions with juvenile shrimp (1.90 ± 0.10 g, initial weight). In trial 2, juvenile shrimp (0.40 ± 0.01 g, initial weight) were fed similar diets where lysine was supplemented in diets with high levels of GDDY (200 and 300 g/kg of diet). The results from this study demonstrate that inclusion of GDDY up to 300 g/kg of diet did not cause negative effects on final biomass, mean final weight, feed conversion ratio, and survival. Furthermore, the addition of lysine to diets with high levels of GDDY (200 and 300 g/kg of diet) did not enhance growth performance under the reported conditions, confirming lysine was not limiting. Consequently, these results indicate that up to 300 g GDDY/kg of diet can be used in practical diets for L. vannamei in a clear water system.

Accurate digestibility coefficients for protein, energy, and lipid are needed by feed formulators to optimize diets to meet nutritional requirements and to substitute ingredients cost-effectively. Of particular interest is protein, which accounts for the majority of shrimp feed content and expense. The current study evaluated seven cottonseed meal and protein products. Most of the samples were derived from a glandless cotton variety that lacks significant levels of the antinutritive compound, gossypol. The various protein fractions were evaluated for apparent crude protein, crude lipid, and energy digestibility when fed to juvenile Pacific White Shrimp, Litopenaeus vannamei. Apparent energy digestibility for the protein fractions derived from the glandless seed ranged from 76.7% for ground kernels to 94.6% for protein isolate, and these values were greater than the value obtained for the commercial meal that contained gossypol (64%). Apparent protein digestibility for the six glandless-cotton-based samples varied from 72.3% for the ground full-fat kernels to 94.1% for the protein isolate, and these values were mostly higher than the value obtained for the commercial meal (82.3%). The high apparent digestibility values demonstrate that low-gossypol cottonseed protein products may be useful as a cost-effective replacement for more expensive protein sources in L. vannamei diets.

The white spot syndrome virus (WSSV) remains the most devastating viral pathogen of shrimp culture worldwide. Gene silencing by RNA interference (RNAi) using double stranded RNA (dsRNA) has been considered a powerful tool for conferring protection against WSSV when viral genes are silenced, as documented in several shrimp species. However, this effect is not long lasting. Our results provide the first evidence that long-term silencing of the LvRab7 endogen produced antiviral effect against WSSV, which endured at least 21 d after dsRNA treatment (dat). Until now, the most efficient way to implement RNAi with dsRNA into the shrimp is by injection. Consequently, its application to broodstock in hatcheries is possible, minimizing the risk of vertical transmission of the virus. We show that the expression of Rab7 in hemocytes is lowest at 2 dat and finally recovers to basal status. In contrast, in gills and pleopods, gene expression silencing continued for at least 21 d. We challenged Litopenaeus vannamei broodstock with WSSV at 7, 14, or 21 dat reaching mortality rates of 0, 40, and 27%, respectively. In conclusion, the LvRab7 gene silencing is progressive and effective against WSSV. However, further studies are necessary to elucidate the functions of Rab7 in shrimp cells before applying this methodology at a commercial level.

A 10-week feeding trial was conducted to determine the requirements of vitamin D3 in juvenile Litopenaeus vannamei at low salinity rearing conditions. The basal practical diet contained 685 IU vitamin D3 per kg diet, Diets 2–6 contained 1960, 3240, 4220, 5630, and 7550 IU vitamin D3 per kg diet, respectively. Diets were fed twice daily to triplicate groups of L. vannamei (initial average weight 0.39 ± 0.01 g). Growth performance and alkaline phosphatase activity in hepatosomatic were not affected by the supplementation of vitamin D3. Hepatosomatic index of shrimp fed diets containing vitamin D3 at 685, 1960, and 3240 IU/kg was lower than the diet containing vitamin D3 at 7550 IU. Whole-body moisture and zinc content were significantly decreased with increasing vitamin D3. Similarly, higher value was also observed on whole-body protein, ash content, calcium, and phosphorus and magnesium concentration with increasing vitamin D3. Results of the current study indicated that vitamin D3 from ingredients could meet the growth requirement but not for whole-body mineral deposition. Broken-line regression analysis based on maximum whole-body ash indicated that vitamin D3 requirement was recommended to be 6366 IU/kg for juvenile L. vannamei at low salinity rearing conditions.

The objective of this study was to investigate the effect of inbreeding on body weight (BW) at harvest size (130 d of age) and grow-out survival rate (SR) (65–130 d of age) in a nucleus breeding population of Penaeus (Litopenaeus) vannamei. An experiment was designed to generate inbred families the product of sibling matings, as well as groups of families with different inbreeding coefficients in three successive generations. The families came from a broodstock line selected for growth and survival. Inbreeding coefficients varied between 0 and 60.4%. A total of 16,361 shrimp from 320 families were produced. Data were analyzed using mixed linear model methodology and restricted maximum likelihood methods. Estimated change on BW per 10% increase on the inbreeding coefficient was −2.19 ± 0.41% (P

The nutritional contribution of the dietary nitrogen supplied by poultry by-product meal (PBM) and fish meal (FM) to the somatic growth of Pacific white shrimp, Litopenaeus vannamei was assessed by means of stable isotope analysis. Seven experimental diets were formulated with different proportions of PBM replacing FM. Mixed diets were formulated to replace 0, 35, 50, 65, 80, 95 and 100 % of FM with PBM, on a dietary nitrogen basis. At the end of the experiment, there were no significant differences in survival among dietary treatments (89±5 %); however, significant differences in final wet weights were observed. Diets having FM replacement levels of 35 and 50% with PBM, promoted mean final weights (708-789 mg) similar to those observed in shrimps fed on diet containing 100% FM (874 mg). Shrimp final mean weight significantly decreased as a function of PBM inclusion (r= -0.98) due to the use of only two dietary nitrogen sources and by possible nutritional restrictions as PBM levels increased. The relative proportions of dietary nitrogen supplied by PBM and FM were incorporated in muscle tissue at proportions that were statistically similar to those established in the dietary formulations.

The use of the same water over multiple culture cycles in a biofloc technology system can be highly beneficial. This study evaluated the effect of different levels of biofloc-rich water on selected water quality indicators and on the productive performance of Pacific white shrimp, Litopenaeus vannamei, juveniles (3.5g) stocked at 312 juveniles/m 3 and cultured under conditions of no water exchange. The study was performed over a 30-d period in an 800-L tank system. A total of four biofloc enrichment levels (25, 50, 75, and 100%) and control (0%) were tested with three replicates each. Significant differences in nitrogen compounds were found between the biofloc-enriched water and the zero-enrichment treatment. No statistically significant differences among the biofloc-enriched treatments were found in survival, final weight (8.25g), and feed conversion ratio (FCR) (1.08). The shrimp raised in clear seawater (i.e., a 0% biofloc enrichment) were significantly smaller (7.37g vs. 8.25g) and showed a higher FCR (1.52 vs. 1.08) than the shrimp cultured in the biofloc-rich water. Nevertheless, no differences in yields were found between treatments. The results of this study suggest that culture in biofloc-enriched water produces higher levels of water quality and shrimp performance than culture in natural seawater.