Unveiling the positive impact of biofloc culture on Vibrio parahaemolyticus infection of Pacific white shrimp by reducing quorum sensing and virulence gene expression and enhancing immunity.

This study aimed to evaluate and unveil the positive impact of biofloc culture on Vibrio parahaemolyticus infection of Pacific white shrimp by reducing quorum sensing (QS) and virulence gene expression and enhancing shrimp's immunity. The shrimp with an average body weight of 0.50 ± 0.09 g were reared in containers with a volume of 2.5 L, 21 units, and a density of 20 shrimp L-1. The shrimp were cultured for 5 days, with each treatment including biofloc system maintenance with a C/N ratio of 10 and a control treatment without biofloc, followed by a challenge test through immersion using V. parahaemolyticus at densities of 103, 105, and 107 CFU mL-1 initially. The results of the in vitro experiment showed that biofloc suspension can inhibit and disperse biofilm formation, as well as reduce the exo-enzyme activity (amylase, protease, and chitinase) of V. parahaemolyticus. Furthermore, the biofloc treatment significantly reduced the expression of the QS regulatory gene OpaR, the PirB toxin gene, and the virulence factor genes T6SS1 and T6SS2 in both in vitro and in vivo. The biofloc system also increased the expression of shrimp immunity-related genes (LGBP, proPO, SP, and PE) and the survival rate of white shrimp challenged with V. parahaemolyticus.

Dietary supplementation of cinnamaldehyde positively affects the physiology, feed utilization, growth, and body composition of striped catfish Pangasianodon hypophthalmus.

The study evaluated the effects of diverse cinnamaldehyde (CIN) supplementation doses on the physiological attributes, feed utilization, growth, and body composition of striped catfish Pangasianodon hypophthalmus. The study incorporated five doses of CIN supplementation, namely 0, 0.5, 1, 1.5, and 2 g kg-1 feed, with four replicates per group. Commercial extruded isonitrogenous and isoenergetic feeds with crude protein and gross energy levels of 28.46% ± 0.23% and 3858.70 ± 18.06 kcal kg-1, respectively, were used as test feeds. The initial weight of striped catfish was 5.57 ± 0.02 g, and 30 fish were maintained in each cage (2 × 1 × 1 m3) for 60 days. The results illustrated that the incorporation of CIN into the diet increases amylase and lipase levels and the ability of striped catfish to accumulate glucose, as the glucose tolerance test revealed that CIN 1.0 and 1.5 g kg-1 reduced glucose content to its basal level at 3-4 h postinjection and upregulated the insulin receptor, hexokinase, and hormone-sensitive lipase genes. CIN 1.5 g kg-1 also increased plasma total protein and high-density lipoprotein levels and reduced triglyceride and cholesterol levels. CIN 1.0-2.0 g kg-1 increased antioxidant capacity by increasing the levels of superoxide dismutase and glutathione and decreasing malondialdehyde levels. CIN 1.5 g kg-1 was the best treatment for increasing final weight, the specific growth rate, protein retention, and the protein efficiency ratio and for decreasing the feed conversion ratio. CIN additionally increased meat protein and decreased meat and liver lipid content. This study concluded that 1.24 g kg-1 is the optimal CIN dose calculated from the equation Y = - 0.1487x2 + 0.3702x + 5.0724 (R2 = 0.71) to increase growth and feed efficiency in striped catfish by increasing nonprotein catabolism and exerting antioxidant effects.

Evaluation of Growth and Health Performance of Juvenile Tilapia Oreochromis sp. Fed with Various Supplementation of Heat-Killed Lactobacillus plantarum.

Thus, this research was conducted to evaluate the supplementation of heat-killed Lactobacillus plantarum at higher dosages and investigate the effect of heat-killed L. plantarum supplementation on the challenges of Streptococcus agalactiae. A feeding trial was conducted for 90 (initial average body weight of 12.52-12.69 g) days, while a disease challenge was conducted for 17 days. Dietary treatments were formulated to have a ranging level of heat-killed L. plantarum L-137: (1) control treatment without heat-killed L. plantarum, (2) diet containing 10 mg/kg heat-killed L. plantarum L-137 preparation (LP20, which contains 20% heat-killed L. plantarum L-137), (3) diet containing 20 mg/kg LP20, (4) diet containing 100 mg/kg LP20, and (5) diet containing 250 mg/kg LP20. All the diets were formulated to have equal values of protein and energy. Dietary supplementation of heat-killed L. plantarum L-137 improved tilapia growth performance and higher robustness against S. agalactiae infection. Therefore, a 10-20 mg/kg LP20 feed supplementation level is recommended to support the tilapia growth. In addition, an LP20 dietary supplementation level of 250 mg/kg feed is recommended for higher protection against S. agalactiae.

High carbohydrate increases amylase, plasma glucose, and gene expression related to glycolysis in giant gourami Osphronemus goramy.

The present study elucidated hepatic molecular and physiological responses of giant gourami to high dietary carbohydrates. Two levels of dietary carbohydrate, normal carbohydrate (34%, NC) and high carbohydrate (53%, HC), were offered to the fish for 60 days. We evaluated the expression of genes that are related to carbohydrate metabolism, lipogenic capacities, amino acid catabolism, Krebs cycle, and energy sensing. In addition, we also observed the digestive enzyme activities, plasma glucose, glycogen content, whole-body composition, and growth performance of the fish. On day 30 after treatment, fish fed with high dietary carbohydrate level has significantly higher expression of gck, pk, hk, and ldh than the NC group (P < 0.05). In contrast, fish in the HC group had lower expression of irs1, igf-1, sdh, fbp, g6pc, gyp, and ampk compared to the NC fish (P < 0.05). On day 60 of the feeding trial, gck and hk expressions were still higher in the HC group (P < 0.05), and gyp, gdh, and ampk became increasingly expressed in the HC group. The increase of dietary carbohydrates resulted in significant increases in amylase and protease activity, plasma glucose, liver glycogen, crude protein, and lipid contents of the fish whole-body (P < 0.05). The high carbohydrate feeding reduced the fish growth rate but increased feed efficiency and did not affect mortality. In conclusion, giant gourami could utilize high carbohydrates due to a high amylase secretion, high modulation of carbohydrate metabolism, and large glucose storage capacity.

Protective effects of the biofloc system in Pacific white shrimp (Penaeus vannamei) culture against pathogenic Vibrio parahaemolyticus infection.

The mitigation of vibriosis in shrimp culture could be accomplished by reducing the virulence of the pathogen or by increasing the immune response of the shrimp. This study aims to evaluate the application of a biofloc system in protecting Pacific white shrimp (Penaeus vannamei) from pathogenic Vibrio parahaemolyticus infection. Shrimp post-larvae (PL 20) with an average body weight of 0.041 ± 0.019 g were reared in an aquarium with a working volume of 33 L at a density of 3 L-1 for 21 days using two rearing systems, i.e., the biofloc system and the regular clear water system as control. In each system, the shrimp post-larvae were challenged by adding V. parahaemolyticus at different densities, 103, 105, and 107 CFU mL-1, while the negative control was performed by maintaining shrimp post-larvae in the clear water system without the addition of V. parahaemolyticus. The results of the in vitro experiment showed that the density and biofilm activity of V. parahaemolyticus reared in biofloc suspension was lower than that of the positive control (p < 0.05). The density of V. parahaemolyticus in shrimp rearing water was lower than that in the control at 105 CFU mL-1, especially on the 3rd day post-challenge, but there was no significant difference in the total presumptive Vibrio count between the biofloc treatment and the control. The survival, growth, and immune response parameters, such as total hemocyte count, phagocytic activity, respiratory burst, and phenoloxidase activity, of the shrimp, reared in the biofloc system were also higher than those of the positive control (p < 0.05), regardless of the density of V. parahaemolyticus. The present study demonstrated that the application of biofloc could significantly protect and increase the resistance of Pacific white shrimp against pathogenic V. parahaemolyticus infection.

Biofloc technology application in aquaculture to support sustainable development goals.

Biofloc technology (BFT) application offers benefits in improving aquaculture production that could contribute to the achievement of sustainable development goals. This technology could result in higher productivity with less impact to the environment. Furthermore, biofloc systems may be developed and performed in integration with other food production, thus promoting productive integrated systems, aiming at producing more food and feed from the same area of land with fewer input. The biofloc technology is still in its infant stage. A lot more research is needed to optimise the system (in relation to operational parameters) e.g. in relation to nutrient recycling, MAMP production, immunological effects. In addition research findings will need to be communicated to farmers as the implementation of biofloc technology will require upgrading their skills.

Immune response and disease resistance of shrimp fed biofloc grown on different carbon sources.

The objective of this study was to document the immunological effects of growing shrimp in biofloc systems. The experiment consisted of four types of biofloc systems in which bioflocs were produced by daily supplementation of four different carbon sources, i.e. molasses, tapioca, tapioca-by-product, and rice bran, at an estimated C/N ratio of 15 and a control system without any organic carbon addition. Each biofloc system was stocked with Pacific white shrimp (Litopenaeus vannamei) juveniles that were reared for 49 days. The use of tapioca-by-product resulted in a higher survival (93%) of the shrimp as compared to the other carbon sources and the control. The highest yield and protein assimilation was observed when tapioca was used as the carbon source. After 49 days, phenoloxidase (PO) activity of the shrimp grown in all biofloc systems was higher than that of the shrimp from the control system. Following a challenge test by injection with infectious myonecrosis virus (IMNV), the levels of PO and respiratory burst (RB) activity in the shrimp of all biofloc treatments were higher than that of the challenged shrimp from the control treatment. An increased immunity was also suggested by the survival of the challenged shrimp from the experimental biofloc groups that was significantly higher as compared to the challenged shrimp from the control treatment, regardless of the organic carbon source used to grow the bioflocs. Overall, this study demonstrated that the application of biofloc technology may contribute to the robustness of cultured shrimp by immunostimulation and that this effect is independent of the type of carbon source used to grow the flocs.