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Free fatty acids have long been used as dietary supplements in aquaculture, but the application of monoglycerides has increased interest in more recent times. The study aimed to investigate the effects of dietary short- and medium-chain fatty acid monoglyceride and cinnamaldehyde (SMMG) on the growth performance, survival, immune responses, and tolerance to hypoxic stress of Pacific white shrimp (Litopenaeus vannamei). In Experiment 1, shrimp post-larvae were divided into 4 groups with 6 replicates and fed with diets supplemented with 0 (control), 0.3, 0.4, and 0.5% diet for 30 days. The final body weight and survival rate were determined. In Experiment 2, the juvenile shrimp from Experiment 1 were subjected to hypoxic stress conditions (dissolved oxygen level 2–2.5 mg/L) for 14 days, then the specific growth rate (SGR), survival rate, intestinal Vibrio spp. count, immune responses, and histopathological change of the hepatopancreas were analyzed. Following the 30-day feeding trial, the results revealed that the final body weight and survival of the 0.3–0.5% SMMG groups (2.81–3.06 g and 74.00–84.33%, respectively) were significantly higher than the control shrimp (1.96 g and 68.33%, respectively). In the hypoxic stress experiment, the survival rates of shrimp fed 0.4–0.5% SMMG (71.67–80.00%) were significantly higher than the control (51.67%). Although the SGR were not affected by SMMG supplementation, all immune parameters evaluated were significantly enhanced, and the intestinal Vibrio spp. counts were significantly decreased in the 0.4–0.5% SMMG-fed shrimp; the histopathological structure of the hepatopancreas was also improved in these shrimp compared to the control. Our findings indicated that SMMG as a feed additive has beneficial effects in improving shrimp health and increasing tolerance to hypoxic conditions. [ABSTRACT FROM AUTHOR]

The study aimed to evaluate the effect of tributyrin on the growth performance, survival, hypoxia tolerance, and nutrient digestibility of Pacific white shrimp fed 25% and 50% soybean meal (SBM) diets. Six experimental diets were formulated: (1) 25% SBM without tributyrin; (2) 25% SBM with 0.05% tributyrin; (3) 25% SBM with 0.1% tributyrin; (4) 50% SBM without tributyrin; (5) 50% SBM with 0.05% tributyrin; and (6) 50% SBM with 0.1% tributyrin. The shrimp were fed the experimental diets daily for 10 weeks. Tributyrin supplementation at 0.1% diet significantly improved the weight gain of shrimp that fed 25% SBM but not the other groups. Nevertheless, shrimp that fed tributyrin had significant improvement in survival rate at both SBM levels. Significant reductions in Vibrio spp. counts in the hepatopancreas and intestine were also evident in all tributyrin‐fed groups. In addition, 0.1% tributyrin in both SBM levels significantly enhanced the shrimp tolerance to hypoxia. Lastly, the digestibilities were generally unaffected by the tributyrin except only for the lipid digestibility of the 0.1% tributyrin in 25% SBM group, which showed a significant increase. Overall, tributyrin was proven beneficial for the shrimp's health, especially for those fed diet with a moderate level of SBM (25%). [ABSTRACT FROM AUTHOR]

Drug behavior in the bodies of fish is largely influenced by the water temperature. Antimicrobial drugs are needed for the control of bacterial outbreaks in farmed fish including Asian seabass (Lates calcarifer). However, little is known about the temperature effect on appropriate drug uses in this species. The purpose of this study was to investigate the differences in pharmacokinetics (PK), optimal dosages, tissue depletion, and withdrawal time (WDT) of florfenicol (FF) in Asian seabass reared at 25 and 30 °C. In the PK study, the fish were administered with a single oral dose of 10 mg/kg FF. The optimal dosing regimen was determined by the pharmacokinetic-pharmacodynamic (PK-PD) approach. In the tissue depletion and WDT study, FF was administered at the optimal dosages once daily for 5 days and the WDT was determined by linear regression analysis based on the sum of FF and its metabolite florfenicol amine (FFA) in the muscle/skin. When the temperature was increased from 25 to 30 °C, the elimination half-life of FF was significantly decreased from 11.0 to 7.2 h. While the other PK parameters were not changed significantly, the calculated optimal dosages for the target minimum inhibitory concentration (MIC) of 2 µg/mL were 10.9 and 22.0 mg/kg/day, respectively for 25 and 30 °C. The sum of FF + FFA is a preferable marker residue for WDT determination because differential FF metabolism was observed at different temperatures. The depletion half-life of the muscle/skin was shortened from 41.1 to 32.4 h by the 5 °C temperature increase. Despite different absolute amounts of FF given between the two temperature levels, the WDTs were very similar at 6-7 days. Thus, it appears that a single temperature-independent WDT can potentially be assigned when the drug was applied at the optimal dosage. [ABSTRACT FROM AUTHOR]

Asian seabass (Lates calcarifer) is an economically important fish in Asian and Australian markets, but few pharmacokinetic (PK) data of antimicrobial drugs in this species is available. The present study investigated the PK behaviour of florfenicol (FF) through medicated feed in Asian seabass cultured at 25°C. The serum and muscle/skin concentrations of FF and its metabolite florfenicol amine (FFA) were determined by the HPLC‐FLD method and analysed by one‐compartmental model. The optimal dosages were determined by pharmacokinetic‐pharmacodynamic (PK‐PD) approach and the linear regression analysis was used to determine the withdrawal time (WDT). The PK study following a single oral administration of 15 mg/kg FF via medicated feed revealed that the absorption half‐life (t1/2Ka), elimination half‐life (t1/2K), peak concentration (Cmax), area under the concentration‐time curve (AUC), volume of distribution (Vd/F) and clearance (CL/F) were 1.47 h, 8.07 h, 8.61 μg/ml, 146.41 h·μg/ml, 1.19 L/kg and 0.102 L/kg/h, respectively. The muscle/skin concentration‐time profile was similar to that of the serum, suggesting well distribution but only a small fraction of FF was metabolized to FFA. The optimal dosage for a minimum inhibitory concentration of 2 μg/ml was calculated as 13.38 mg/kg/day. The appropriate WDT after multiple oral medications with 15 mg/kg FF once daily for 7 days was determined as 8 days. Information obtained from the current study can potentially be applied for the treatment of bacterial diseases in farming Asian seabass. [ABSTRACT FROM AUTHOR]

We evaluated the advantages of all-male giant freshwater prawn (Macrobrachium rosenbergii) culture over traditional mixed-sex and all-female systems in the aspects of growth performance, production yield, and profitability. The prawn post-larvae were reared in a nursery pond for 43 days until the male sexual characteristics (gonopore complex) could be distinguished externally, then they were sexed and transferred to monosex grow-out ponds (two ponds per sex) and cultured for another 140 days. The prawn post-larvae in the mixed-sex group were reared for 60 days in the nursery phase and 165 days in the grow-out phase. At harvest, the male prawns from the all-male group had higher body weight (93.02 g), average daily growth (0.66 g.day-1), and specific growth rate (3.41 %.day-1), compared to the males in the mixed-sex system (69.38 g, 0.41 g.day-1, and 2.56 %.day-1, respectively). The proportion of an unfavorable "small male" morphotype was reduced from 20.11 % in the mixed-sex culture to 4.67 % in the all-male system, whereas that of a desirable "orange claw" morphotype was increased from 38.59 to 61.33 %. Ultimately, the production yield of the all-male group was 2,076.6 kg·ha-1, whereas that of the mixed-sex system was 1,273.8 kg.ha-1. The cost-benefit analysis revealed that the former was 155.78 % more profitable than the latter. The all-female group showed the best survival rate and feed conversion ratio, yet it was the least profitable system. In conclusion, the all-male culture was the most productive and profitable system of giant freshwater prawn farming. [ABSTRACT FROM AUTHOR]

This study examined the effect of substituting a diet containing 20% fish meal (FM) and 10% soy bean meal (SBM) with Bacillus-fermented soybean meal (FSBM) on growth, immune response, microbial community in the hepatopancreas, and disease prevention in Pacific white shrimp. Shrimp were fed diets with four levels of FSBM (0%, 15%, 20% and 25%) to replace FM and SBM. After 60 days of the feeding trial, no difference was found among treatments for specific growth rate (1.62-1.66 g), survival rate (88.08-93.64 %), feed conversion ratio (FCR) (1.31-1.41), or protein efficiency ratio (88.08-93.46). However, shrimp fed 25% FSBM showed a significant improvement in total hemocyte count (THC), phagocytic activity, and phenoloxidase activity (PO) compared with other groups. In the hepatopancreatic microbiota, we identified six phyla, of which Bacteroidetes was the most dominant phylum in the three groups fed with FSBM. In contrast, Firmicutes was dominant in the control group. After a challenge test with Vibrio parahaemolyticus, shrimp fed 25% FSBM had a significantly higher average survival rate compared with other experimental groups infected with V. parahaemolyticus. The histopathology of the hepatopancreas of shrimp from this group showed fewer signs of bacterial infection than other groups infected with V. parahaemolyticus. This study indicates that FSBM at the concentration of 25% can enhance immune response and tolerance to pathogenic V. parahaemolyticus in the Pacific white shrimp. [ABSTRACT FROM AUTHOR]

A 60-day feeding trial was conducted with Pacific white shrimp (Litopenaeus vannamei) postlarvae 12 (PL 12) to ascertain the effectiveness of using a giant bladder kelp as a feed additive. Shrimp growth, feed efficiency, survival, and immune response were evaluated. Postlarvae (PL) 12 were stocked in 16 × 500-L fiberglass tanks at a density of 50 PLs - tank-1. Water temperature and salinity were maintained at 29 ± 1 °C and 20-25 ppt, respectively. The shrimp were distributed into four groups (four replicates/treatment) and fed four times "day-1 with standard normal pelleted shrimp feed (control group) or feed mixed with 1, 2 and 3% by weight of the giant bladder kelp feed additive. The final weights and survival rates of shrimp were not significantly different among all treatments. However, shrimp raised on diets supplemented with giant bladder kelp showed significant improvement in their immune responses, including phenoloxidase and phagocytosis activities. The immune response of shrimp was significantly influenced by the percentage of the giant bladder kelp feed additive present in the shrimp feed. Shrimp fed with a diet containing 3% giant bladder kelp had significantly higher total hemocyte counts and percentages of phagocytosis, phenoloxidase, superoxide dismutase and bactericidal activities compared with the control group. Moroever, the survival rate of shrimp after challenging with Vibrio parahaemolylicus when fed diets containing 2 and 3% of giant bladder kelp were significantly increased compared with that of the control group. These findings demonstrated that the giant bladder kelp feed additive used in this study had a positive effect on the shrimp postlarval nonspecific immune responses and survival after being challenged with Vibrio kparahaemolyticus. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the histopathology of a parvovirus-like agent in the hepatopancreas of freshwater prawns Macrobrachium rosenbergii from hatcheries in Ratchaburi, Thailand. For the study, samples of two postlarvae (PL) batches and two female broodstock specimens were gathered from hatcheries in Thailand. Analysis of affected nuclei by transmission electron microscopy (TEM) showed that the intranuclear inclusions have small particles, same to those reported for other parvoviruses in marine shrimp. Researchers found that the virus seems to most closely resemble hepanviruses from penaeid shrimp.