Journal of The World Aquaculture Society最新文献

This study was designed to explore the dietary effects of Capsicum annuum oleoresin (CAO) on growth, body composition, sensory characteristics, gut microbiome, and intestinal histomorphometry of rainbow trout. Fish (195.13 ± 1.55 g) were fed diets with various CAO levels (0.0-Control, 7.0- g kg ⁻¹ C7, 14.0 g kg ⁻¹ -C14, 21.0 g kg ⁻¹-C21, and 28.0 g kg ⁻¹-C28) for a 30-day period. Results revealed that the maximum growth was achieved in C7 and C14 groups. Nevertheless, the growth parameters were similar in other groups compared to the control. Moreover, there were significant increases in dry matter and crude lipid contents in all CAO groups compared with the controls. The mean abundances (%) of the prevalent bacteria at the genus level in the intestinal trout samples presented no significant changes among the test groups. Dietary CAO significantly changed the intestinal histological structure, and was manifested by an increased number of goblet cells in the CAO-supplied groups. However, there were intestinal villus epithelial deformations associated with increasing dietary CAO, and were most prominent in the C28 group. The sensory attributes of cooked trout fillets showed that capsicum's pungent odor and taste was evident in the C14 group and subsequently increased with increasing dietary CAO levels. Accordingly, the results showed, for the first time, that dietary CAO at levels (7–14 g kg⁻¹) can enhance the growth of rainbow trout without negative effects on the sensory characters and gut health.

Most studies evaluating the use of distiller's dried grains with solubles (DDGS) to partially replace the use of soybean meal (SBM) in diets of shrimp Litopenaeus vannamei have been carried out under laboratory conditions, which has significant differences in terms of environmental and culture conditions with the out-door commercial pond. This study aims to extrapolate the laboratory trials into the out-door pond condition in order to evaluate the feasibility of incorporating DDGS at various levels (D0 (0%), D5 (5%), D10 (10%), and D 15 (15%)) to replace the use of SBM for 90-day culture period on the growth, body composition, total hemocyte count, lysozyme activity, and organoleptic characteristics of the shrimp. Seven hundred twenty shrimp (mean initial weight 1.06 ± 0.01 g) were randomly distributed into each of 40 net pens (3 × 2 × 1 per net pen) with 10 replicates per dietary treatment. The results showed an enhancement in biomass, mean weight, and thermal growth coefficient of shrimp fed with 5 and 10% inclusion levels of DDGS. Significant reduction of FCR was also observed with the use of 5 and 10% DDGS to partially replace SBM. There were no severe changes in the total hemocyte count (THC), lysozyme activity, color, aroma, and flavor of the shrimp. However, the texture of shrimp was significantly better with the use of 10 and 15% DDGS in the diet. In summary, regarding all the factors, DDGS is a promising alternative ingredient to replace the use of SBM with 5 and 10% inclusion levels and could modulate better growth, quality, and maintain the health condition of shrimp cultured in out-door pond conditions.

In order to screen out the feeding ratio of high-quality algae strains in Hyriopsis cumingii, this experiment investigated the effects of different ratio of mixed feeding of two algae strains (Scenedesmus dimorphus and Cyclotella sp.) on the growth, bead production performance, trace elements, and amino acid composition of the newborn shell of H. cumingii. The results showed that the mixed feeding of two types of microalgae with different densities had significant effects on the growth performance, bead production quality, trace elements, and amino acid composition of the newly formed shell of H. cumingii (p < 0.05); the best body weight gain rate and shell growth rate were obtained by feeding S. dimorphus (30 × 10⁵ cell/mL) and Cyclopella sp.(8 × 10⁵ cell/mL); the pearl weight gain rate, amino acid ratio, Ca²⁺ and Mn²⁺ content were best when feeding Cyclotella sp. (16 × 10⁵ cell/mL), but there was no significant difference compared with S. dimorphus (30 × 10⁵ cell/mL) and Cyclopella sp.(8 × 10⁵ cell/mL). In summary, the optimal feeding amount for the intensive breeding process of H. cumingii is S. dimorphus (30 × 10⁵ cell/mL) and Cyclopella sp. (8 × 10⁵ cell/mL).

The dietary protein levels and source of starch are factors in the economical production of feeds, which may change the physical quality of extruded pellets and the growth performance of fish. Eight feeds contained two protein levels and four levels of wheat flour substitutions by corn, as a 2 × 4 factorial experimental design, were produced by a twin-screw extruder machine and fed to 800 rainbow trout. The results showed corn grain reduced expansion ratio, water stability at 120 and 260 min, starch gelatinization (SG), and apparent degradability, while bulk density (BD) and oil leakage of feed pellets increased. The high protein diets displayed the most BD, lower oil leakage, SG, and elastic modulus. The high protein feeds improved the final body weight, weight gain, specific growth rate, and feed conversion ratio (FCR) of fish. The corn grain reduced the FCR and promoted the trout's protein efficiency ratio. Lipid proportions of fish livers corresponded to hepatosomatic index and serum concentrations of aspartate aminotransferase and alanine aminotransferase. In general, corn, as the starch source in the high and low-protein extruded feeds, can be replaced at levels of 33%–66% of wheat flour without adverse effects on the physical characteristics of feed pellets and the growth performance of rainbow trout.

Based upon mixed linear model and incomplete diallel cross between different strains of Macrobrachium nipponense, the additive-genetic correlations of growth and morphometrics with meat yield traits in M. nipponense were estimated using the minimum norm quadratic unbiased estimation procedure. Path analysis method was utilized to investigate the overall additive-genetic determinations of growth and morphometric traits on the meat yield traits. Results indicated that growth and morphometrics were genetically positively correlated with abdominal meat weight (p < 0.01), but were not genetically correlated with abdominal meat percentage (p > 0.05) in both sexes. Growth and morphometrics were genetically positively correlated (p < 0.01). Abdominal meat weight was genetically positively correlated with abdominal meat percentage (p < 0.01). In terms of the overall additive-genetic determination, body weight had the greatest impact on abdominal meat weight in both sexes. In contrast, abdominal meat weight, abdominal length, and body weight were most influential on abdominal meat percentage in both sexes. The genetic relationships of growth and morphometrics to meat yield traits were elucidated in M. nipponense for the first time, contributing to formulation of sound improvement plan for the meat yield traits in this commercially important prawn species.

Toll-like receptors (TLRs) are an important family of pattern-recognition receptors that recognize a series of pathogen-associated molecular patterns to trigger the host immune response. In the present study, we identified three TLR13 genes (i.e., LcLTR13a, LcTLR13b, and LcTLR13c) in American bullfrogs, Lithobates catesbeianus, and explored their constitutive and pathogen-induced expression profile in different tissues. The open reading frames of LcLTR13a, LcTLR13b and LcTLR13c are 2811, 2844, and 2814 bp long, encoding 955, 947, and 933 amino acids, respectively. Phylogenetic analysis showed that three LcTLR13 genes grouping in different subclades indicate the gene duplication of bullfrog TLR13 as in teleost. The three LcTLR13 genes were expressed in all the tissues examined, with the liver and spleen expressing the higher levels. Moreover, the expression levels of LcLTR13a, LcTLR13b, and LcTLR13c were significantly induced in the liver and spleen after bullfrogs were challenged with bacterial (i.e., Citrobacter freundii, Aeromonas hydrophila, and Edwardsiella tarda) pathogens. These results indicate that LcTLR13 genes play an essential role in the bullfrog antibacterial innate immune response, providing new insights into immune mechanisms of bullfrogs.

Gut microbiota impacts fish metabolism, nutrient utilization, and health. We know little about how temperature and diet interact with rainbow trout gut microbes. A total of 288 fish (average body weight: 45.6 g) fed four iso-caloric, -lipidic, and -nitrogenous diets comprised crude protein (40%) and lipid (20%) manufactured as 100% animal-based protein (AP) and blend of 50 fish oil (FO)/50 camelina oil (CO), 100% AP and 100% CO, 100% plant-based protein (PP) and blend of 50 FO/50 CO or 100% PP and 100% CO at 14 or 18°C water temperature. Gut content was analyzed using 16S rRNA gene and shotgun sequencing. Alpha-diversity did not change significantly. Regardless of diet, Tenericutes, Firmicutes, Proteobacteria, Spirochaetes, Bacteroidetes, and Actinobacteria dominated. At family level, Aeromonadaceae and Enterobacteriaceae dominated at 18°C, while Mycoplasmataceae dominated at 14°C. Moreover, genes relating to amino acid, carbohydrate, fat, and energy metabolisms and fatty acid biosynthesis significantly increased at 18°C. Functional profiles did not vary significantly among diets, except for a higher methionine and cysteine metabolism in fish fed plant ingredient compared animal diet, suggesting trout fed plant-derived protein mixed with CO could be as effective as those fed fish meals mixed with 50/50 FO and CO.

Mannan oligosaccharides (MOS) have shown to stimulate immune response in different fish species, but the results may appear contradictory and have not been tested in conjunction with vaccination. We hypothesized that dietary MOS supplementation could enhance efficacy and immune responses after immunization with a novel hydrogen peroxide-inactivated vaccine. Nile Tilapia, Oreochromis niloticus, fingerlings were distributed into four groups (supplemented or not, vaccinated or not) and were used to determine immune and hematological parameters and somatic indexes. For the bacterial challenge and vaccine efficacy test, fish were assigned to five experimental groups. Twenty-eight days after the feeding trial and vaccination, the groups were challenged intraperitoneally and monitored for 21 days. The relative percent survival of the groups basal diet-vaccinated and MOS diet-vaccinated were 98.1% and 100.0%, respectively. The dietary inclusion of MOS after vaccination for 28 days had no influence on vaccine efficacy, which could be explained because of the high efficacy of the vaccine itself. Therefore, we suggest that the contribution of MOS supplementation to immune responses after vaccination in fish would be greater for vaccines with lower efficacy, or when tested for heterologous challenges or for crossed protection.

The growth of shrimp production through aquaculture has led to efforts to optimize processes such as nutrition during the prematuration and reproductive phases. This study sought an optimal culture system and diet to enhance the reproductive characteristics of male Litopenaeus vannamei during prematuration: this compared biofloc with clear water, and an experimental pellet (EP) with a mix of fresh food. Effects were measured in terms of shrimp survival, sperm quality, immunological parameters including prophenoloxidase (ProPO) and hemocyte count, nutritional condition measured as metabolites in hemolymph, hepatopancreas, and reproductive tract, oxidative stress biomarkers in the hepatopancreas and reproductive tract, and relative expression of superoxide dismutase, catalase, glutathione peroxidase, ProPO, alpha2-macroglobulin and caspase in reproductive tract. Survival was higher with pellets (100%) than with fresh food (87%). Shrimp that were fed pellets had a higher hepatosomatic index, higher nutrient concentration in the hepatopancreas, and a higher antioxidant activity in the reproductive tract. Notably, sperm quality remained similar regardless of culture system or diet. These promising results should be ratified with a bioeconomic study to check the feasibility of hatcheries to use monosex tanks and feeding the males with EPs.