Aquaculture Research最新文献

This study investigated the effects of commercial probiotics on the growth, feed utilization, hematology, innate immunity, and disease resistance of climbing perch (Anabas testudineus). One gram of each locally available branded commercial probiotic, Pro-1, Pro-2, Pro-3, and Pro-4, was incorporated into commercial fish feed to prepare treatment diets T₁ to T₄, respectively, and feed without any probiotics was used as control (C). After 8 weeks of feeding, all groups demonstrated significantly improved percent weight gain (WG) and specific growth ratio (SGR; except T₃) and lower feed conversion ratio (FCR) relative to C. Moreover, these growth and feed utilization parameters were positively modulated in T₂ compared to C and the other three treatments. Serum biochemical parameters, such as liver stress enzymes alanine aminotransferase (ALT) and aspartate aminotransferase (AST), were lower (p < 0.05) in the probiotic-supplemented group, but variations in triglyceride (TG, mg dl⁻¹) levels were detected. Important hematological parameters, including white blood cells (WBC), lymphocytes (Lymphs), mean corpuscular hemoglobin concentration (MCHC), red blood cell (RBC) distribution width (RDW)-standard deviation (SD), and platelets (PLT), also improved after probiotic administration. Innate immune parameters, such as respiratory burst (RB) in T₃ and alkaline phosphatase (ALP) in T₂ to T₄, also increased. The pathogenetic bacterial challenge with Aeromonas hydrophila (1 × 10⁸ colony-forming units (CFUs)/mL) revealed the enhanced survival rates in T₂ and T₃ compared to other groups. Therefore, locally available commercial probiotic administration through fish diet inoculation enhanced the growth, boosted immunity and hematology, and increased infectious disease protection against A. hydrophila infection in A. testudineus to and ensured the sustainable aquaculture rearing of this species.

Infectious pancreatic necrosis (IPN) has highly contagious disease and an important viral disease-causing economic loss for fish farming, which has developed in recent years. The virus is the first fish virus isolated in vitro. Horizontal and vertical transmission plays an important role in the spread of the virus. In addition, the resistance of the virus to environmental conditions makes it difficult to control the virus. Therefore, it is important to develop vaccines and analyze the effectivity of antivirals for the prevention and control of infectious pancreatic necrosis virus (IPNV) infection. This study investigated the antiviral effect of two different mutagens, ribavirin (RBV) and 5-fluorouracil (5-FU), on IPNV, and their mutation-inducing potential on the susceptible cell line Epithelioma papulosum cyprini (EPC), in vitro. For this purpose, cytotoxic doses of RBV and 5-FU were first investigated and were found to be 50 and 100 µM/mL, respectively. Serial passages of IPNV were then performed, both with and without drug suppression. At the end of each passage, confirmation was performed by real-time transcriptase polymerase chain reaction (RT-PCR). Serial passages were checked for viral load using quantitative RT-PCR (qRT-PCR). The viral copy number of the RBV-suppressed virus decreased from 1.18 × 10⁵ copies/µL for the 1st passage to 1.49 × 10² copies/µL at the end of the 5th passage. The viral copy number of the 5-FU-suppressed virus decreased gradually with each passage, from 3.84 × 10³ copies/µL for the 1st passage to 1.78 × 10² copies/µL at the end of the 5th passage, with the exception of the 2nd passage, where the viral load increased. Passages 1st and 5th of both the RBV- and 5-FU-suppressed virus, and the non-drug-suppressed virus, were checked by partial sequence, but mutations in VP2 were not observed. In conclusion, in this study, we obtained data on the antiviral activity of two mutagens on IPNV.

Over the past three decades, global aquaculture production has significantly increased, emphasizing the need for sustainable and cost-effective alternatives to traditional fish meal in aquafeed. This study’s objective was to elucidate the impact of utilizing a combination of fish and crustacean byproducts—namely, smoked salmon (Salmo salar) skins (SSs), smoked salmon trimmings (STs), and shrimp (Litopenaeus setiferus) heads (SHs)—as primary ingredients in pelleted aquafeed. Importantly, this work focuses on nonextruded pellets, where the physical properties are more influenced by ingredient composition compared to extruded pellets. The tested formulations were not nutritionally comprehensive for any specific commercial aquaculture species, as the goal of this study was to highlight the effect of the byproducts on pellet physical integrity. SH and de-oiled solid fractions of SS and ST were dehydrated for 24 h at 60°C, ground into dried powders, and formulated into six samples at a 1:1 (w/w) ratio and one sample at a 1:1:1 ratio. Potato starch (80 g/kg) was added to each sample, along with varying deionized (DI) water amounts before steam conditioning, pelletizing, and drying. Analyses included pellet nutrient composition, floatability, durability, water stability, bulk density, water absorption index (WAI), and water solubility index (WSI). Results revealed that SS pellets exhibited 97% floatability at 1 min, decreasing to 70% at 60 min. SS and ST combinations showed slow sinking behavior, while all other formulations sank quickly. Pellets containing SH had lower water stability (65.65% ± 4.44% to 0.05% ± 0.07%), in contrast to over 92% for SS and ST pellets. Durability ranged from 98.48% ± 0.37% for SS to 75.29% ± 5.82% for SH and ST combinations, further underlining the significant impact of byproduct choice on pellet performance. Overall, the inclusion of SS or ST and their combination as primary ingredients for pelleted aquafeed produced pellets that scored well on important quality parameters, while pellets containing SH performed poorly. This information may be used in the development of nutritionally comprehensive nonextruded aquafeeds containing SS and/or ST to conduct feeding trials with commercially relevant species.

In order to produce gynogenetic diploid of Manila clam, Ruditapes philippinarum, we studied the optimal conditions of gynogenetic diploid induced by ultraviolet (UV). The irradiance of UV-induced sperm was 230 μW (cm²·s), and the irradiation time was 0, 3, 6, 9, 12, 15, 18, 21, 24, and 27 s. After the egg fertilized with genetically inactivated sperm, the fertilized eggs were treated with cytochalasin B (CB) at different concentrations of 0, 0.25, 0.50, 0.75, and 1.0 mg/L for 20 min. The ploidy of larvae under different induction concentrations were analyzed by flow cytometry, and the chromosome division process during sperm entry and cleavage was observed by fluorescence microscope. In addition, the ultrastructure of sperm, embryonic development, and chromosome were observed. The results showed that the fertilization rate and cleavage rate decreased gradually with the prolongation of UV irradiation time. We found UV irradiation for 9 s was the optimal time for haploid formation, with an induction rate of 100%. The CB treatment at 0.75 mg/L was the optimal concentration for the formation of D-larvae, and the induction rate was 9.60% ± 5.10%. The results showed that the optimal conditions for inducing gynogenetic diploid of R. philippinarum were irradiation with UV intensity of 230 μW (cm²·s) for 9 s and inhibited second polar body release by CB at concentration of 0.75 mg/L. In this study, the conditions for inducing Manila clam gynogenetic diploid were obtained, which lays the basis for further genetic research on the gynogenesis of R. philippinarum.

In order to create new value in biomass production using sterile Ulva with high production efficiency, we selected sterile Ulva with high culture stability from the coast of Imari City in Japan and investigated the conditions for generating high concentrations of dissolved oxygen through photosynthesis using the sterile Ulva. In the cultivation of sterile Ulva, we investigated the conditions for generating high concentrations of dissolved oxygen (DO) by controlling conditions such as aeration, NO₃-N concentration, and population density. As a result, we found that under the cultivation control conditions we found, DO reached about 3.8 times the saturation concentration after 3 h. It was found that this high level of DO can be maintained if the supersaturated DO seawater obtained here is properly sealed. Seawater containing high levels of DO is essential for the cultivation of oysters and shellfish, which also prefer a growth temperature of 20°C−25°C. Therefore, from the perspective of creating new value in biomass production, we developed a new system for simultaneously cultivating sterile Ulva and cultivating oysters.

Aquaponic production relies on microbial activity to convert fish wastes into nutrients for plants. An aquaponic system contains multiple compartments that each have varying environmental pressures that can impact the types of microbes living in the compartment. Furthermore, differences in fish and plant species, system startup and management, and water source can impact microbial communities that colonize an aquaponic system. In this study, we sampled two aquaponic facilities that each operated six replicate aquaponic systems. Metataxonomic analyses were performed on the samples to compare the microbial communities of aquaponic facilities in Minnesota (MN) and Wisconsin (WI), assess the consistency of the microbial communities across multiple systems within a single facility, and evaluate the abundance and types of microbes present within each compartment of a system. Proteobacteria, Bacteroidetes, and Actinobacteria were common in both facilities, but nitrifying organisms were in greater abundance at the WI facility. Microbial communities were largely consistent among systems within a facility, but microbial communities among different compartments of the systems varied. Nitrifying organisms were primarily associated with the biofilter compartment of the MN systems but were found throughout the WI systems, which do not have a dedicated biofiltration compartment. While nitrifying organisms have an important role in an aquaponic system, they comprise less than 10% of the total microbial community of the aquaponic systems we sampled. Other taxa are likely to have equally important roles in the productivity of an aquaponic system, but those taxa and their functions have not been well characterized, and it is unclear how system startup, management, and other factors impact colonization and maintenance of these taxa.

The shortage of lipid sources has been a limiting factor of the aqua-feed industry. Lysophospholipid (LPL) is a highly efficient lipid emulsifier, which may help improve lipid utilization efficiency and thus spare the dietary lipid. This study aimed to evaluate the effects of LPL on growth performance, fatty acid composition, and lipid metabolism of juvenile Litopenaeus vannamei (averagely, 2.4 g). Five diets were prepared: a control diet with 6.5% lipid, the control diet supplemented with 0.05% or 0.1% LPL (0.05% LPL and 0.1% LPL), a moderately low-lipid (MLL) diet supplemented with 0.05% LPL (0.05% LPL-MLL), and an extremely low-lipid (ELL) diet supplemented with 0.1% LPL (0.1% LPL-ELL). Each dietary group had triplicate tanks (30 shrimp in each tank). The feeding experiment lasted 8 weeks. Compared with the control group, the addition of 0.05% LPL promoted the growth by 9.95%; diet 0.05% LPL-MLL resulted in a comparable growth to the control, but diet 0.1% LPL-ELL tended to adversely affect the growth. Dietary LPL had little effect on the whole-body proximate composition. The content of 18:2n−6 and 18:3n−3 was significantly higher in the 0.05% LPL group compared to the control. The 20:5n−3 content was the highest in the 0.05%LPL-MLL group. In addition, the 0.05% LPL and 0.1% LPL group increased the plasma high-density lipoprotein-cholesterol content. Meanwhile, all LPL groups reduced the low-density lipoprotein-cholesterol content. The addition of LPL significantly regulated the messenger RNA (mRNA) expression of genes related to cholesterol homeostasis, such as ldlr, srb1, abca1, and abcg8. In conclusion, dietary supplementation with 0.05% LPL tended to promote shrimp growth and can spare 15% dietary lipid. However, when the dietary lipid content decreased from 6.5% to an extremely low level of 4.8%, dietary LPL was ineffective to spare lipids. This was the first study to validate the lipid-sparing effect of dietary LPL in shrimp.

Among salmonids, brook charr, Salvelinus fontinalis has been gaining popularity in aquaculture. However, major limitations associated with opportunistic diseases that result from unstable egg and fry-rearing conditions are experienced under intensive rearing conditions. Great losses in brook charr culture result from viral (e.g., infectious pancreatic necrosis, viral hemorrhagic septicemia virus), fungal (e.g., saprolegniosis), and bacterial (e.g., furunculosis, cold water disease, columnaris) diseases. Unfortunately, there is no effective treatment for viral diseases for brook charr, and the chemical disinfectants and antibiotics commonly used against bacterial and fungal infections are reaching their limits (pathogen resistance, microbial community disruption), making alternative and more sustainable rearing approaches essential to bolster aquaculture. In this regard, recent studies show that many microbial species (bacteria, archaea, viruses, eukaryotes-like protozoa, and unicellular fungi) are essential from the earliest life stages for the proper development and growth of fish. Based on ecological theory and work on marine fish, it has been hypothesized that current aquaculture practices favor r-strategic, opportunistic microbes that are detrimental to fish health and development. Consequently, to ensure the success and sustainability of brook charr farming, a new aquaculture paradigm involving recirculating aquaculture systems (RAS) that select a K-enriched, specialized microbial community as a preventive measure against those microbial diseases is a very promising avenue. In this review, after introducing brook charr biology, the role of microbes in brook charr rearing and the general problems of disease and low fry survival due to an imbalance in the microbial community will be discussed. Various curative and prophylactic treatment methods currently used to control these diseases and their impact on microbial ecology will be covered, and we will conclude with the rationale of microbial ecology management and its effectiveness in promoting fry survival through disease prevention. To our knowledge, this is the first literature review addressing the promises of managing microbial ecology in a sustainable way in the brook char industry.

The use of fish meal/oil in carnivorous fish feeds remains a concern for the environmental sustainability of aquaculture. In this study, we investigated the impact of an innovative diet designed to be cost-effective and environmentally sustainable (i.e., 60% replacement of fish meal by a blend of plant, yeast [Saccharomyces cerevisiae], and krill meal feed ingredients) on the growth, health, and welfare of gilthead seabream (Sparus aurata). Over a 135-day experiment, fish were fed either the innovative or a commercial diet (control), and various parameters were evaluated, namely growth performance, levels of physiological blood parameters related to stress, immunity, health, and welfare, as well as swimming activity, serving as a proxy for energy expenditure. Results revealed that the innovative diet enhanced growth compared to fish fed the control diet. Hematological and biochemical indicators did not highlight any impaired welfare condition in fish fed innovative diet while higher levels of Immunoglobulin M were measured in plasma of fish fed innovative diet, potentially suggesting enhancement of humoral immunity. However, accelerometer tags data revealed that fish fed the innovative diet exhibited higher overall swimming activity, suggesting higher energy expenditure, which was consistent with greater prealbumin levels measured in the plasma. In conclusion, the higher energy metabolism in fish fed the innovative diet might be compensated by the diet’s content, which may boost humoral immunity and hence help the fish develop a better adaptation to rearing environment, including its viral and bacterial load, ensuring overall better growth. Longer term investigations, including measurements of additional parameters, are required to validate these promising preliminary outcomes.

This study aimed to evaluate the effect of two protein sources (black soldier fly [Hermetia illucens] meal [BSFM] vs. fish meal [FM]) on intake target “diet preference” in juvenile Nile tilapia (Oreochromis niloticus) by a self-feeding method (trial 1). Growth, body composition, blood parameters, and immunity genes expression were also evaluated to be correlated with behavioral data (trial 2). Four experimental diets were prepared containing 0%, 33%, 66%, and 100% BSFM as a substitute for FM protein, which were considered treatments T0 (control), T33, T66, and T100, respectively. In trial 1 (32 days), 60 juveniles (77.97 ± 8.5 g, standard error of the mean [SEM]) were randomly distributed in 60 aquariums (40 L). Fish were challenged to select among A, T0 vs. T33; B, T0 vs. T66; C, T0 vs. T100; D, T33 vs. T66; E, T33 vs. T100; and F, T66 vs. T100 using two floating food halls per aquarium to provide different diets. In trial 2, 240 juveniles (2.80 ± 0.25 g) were distributed in 16 tanks (40 L). The experimental design was completely randomized with four treatments (T0, T33, T66, and T100) and four replies. Fish were fed (5% body weight [BW]) experimental diets for 2 months. For the trial 1 results, no difference was observed in A, T0 vs. T33 (p > 0.05). Fish were allowed to select conditions B, C, D, E, and F and preferred the diets containing no or low BSFM content: B = T0, C = T0, D = T33, E = T33, and F = T66 (p < 0.05). In trial 2, final weight and daily weight gain had lower values when animals were fed 100% FM replacement with BSFM (p < 0.05). The fish fed T0 showed lower viscerosomatic indices (p < 0.05). Moisture and total protein were higher in the fish fed T0, but protein content did not differ from T33 (p > 0.05). Ethereal extract increased with rising BSFM (p < 0.05). There were no significant differences in glucose, creatinine, total protein, high-density lipoprotein (HDL), low-density lipoprotein (LDL), aspartate transaminase (AST), and alanine transaminase (ALT) (p > 0.05). Total cholesterol, triglycerides, and albumin lowered in fish when increase dietary BSFM (p < 0.05). gpx, il-8, il-10, tnf-α, sod, cat, tlr-1, myd, and nf-κb did not differ among treatments (p > 0.05). However, il-1β expression increased in T0 and T100 (p < 0.05). Diets with up to 66% BSFM did not affect performance of juvenile tilapia. However, fish showed a preference for diet containing 33% BSFM.