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Aquaculture International
Journal Prestige (SJR): 0.591  Citation Impact (citeScore): 2 Number of Followers: 25  Hybrid journal (It can contain Open Access articles)ISSN (Print) 1573-143X - ISSN (Online) 0967-6120 Published by Springer-Verlag  [2468 journals]
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- Sodium butyrate suppresses stress, immunosuppression and oxidative stress
in common carp, Cyprinus carpio, reared at high stocking density-
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Abstract: Abstract Organic acid salts can modulate fish growth performance and antioxidant/immune systems, thus they can be used as feed additives for intensive fish culture. Hence, this study investigated the effects of dietary sodium butyrate (NaB) supplementation on growth, antioxidant, immunological and stress indicators in common carp, Cyprinus carpio, reared at high stocking density. Three levels of dietary NaB (0, 1 and 2 g/kg) and two stocking densities [5 (L) and 10 (H) g/L, corresponding to 20 and 40 fish/aquarium, respectively] were combined to have six triplicate treatments: B0-L: 0 g/kg NaB + L; B1-L: 1 g/kg NaB + L; B2-L: 2 g/kg NaB + L; B0-H: 0 g/kg NaB + H; B1-H: 1 g/kg NaB + H; B2-H: 2 g/kg NaB + H. Fish (10.5 ± 0.17 g) were daily fed at a rate of 3% of biomass for eight weeks. The results showed that NaB contributed to stress mitigation by lowering plasma glucose levels and hepatic transaminases, while increasing plasma triiodothyronine levels. NaB boosted antioxidant capacity by increasing hepatic/intestinal superoxide dismutase, catalase and total antioxidant capacity and lowering malondialdehyde levels. NaB supplementation increased blood leukocyte count, neutrophil percentage, alternative complement activity, mucosal/humoral immunoglobulin levels and mucosal/intestinal lysozyme activities. NaB improved growth performance and feed efficiency, likely due to a reduction in stress and energy expenditure and/or an improvement in overall gut and hepatopancreas health and function. Overall, the inclusion of 1 g/kg NaB in the feed is recommended for optimal health and growth performance of common carp kept at high stocking densities.
PubDate: 2024-08-24
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- Potency of cassava leaf as protein source for Nile tilapia (Oreochromis
niloticus)-
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Abstract: Abstract Cassava (Manihot esculenta, Crantz) leaves are cheap and readily available resource that can be used as a feed ingredient for Nile tilapia although they have different constituents that affect their nutritional values. The aim of the study was to examine the effects of processing methods on nutrient content of cassava leaves, digestibility, and growth performance of Nile tilapia. Eight processing methods, namely air-drying, soaking and boiling, baker’s yeast (Saccharomyces cerevisiae), rumen-fluid, molasses, yeast-rumen-fluid, yeast-molasses and molasses-rumen-fluid fermentations, were applied. One control and eight processed cassava leaf-based diets were made. The cassava leaf protein replaced 30% of crude protein (CP) from soybean cake in the control diet. The results showed that CP content in dry matter (DM) varied from 21.7 ± 0.25% (Molasses fermentation) to 30.3 ± 0.25% (Yeast-rumen-fluid fermentation). Rumen-fluid fermentation showed higher (p < 0.05) level of gross energy (21.9 ± 0.02 MJ/kg, DM) and ether extract (12.0 ± 0.21%) compared with other treatments. The apparent digestibility coefficient of CP was generally higher in the control diet (89.9 ± 0.61% in the hindgut), followed by rumen-fluid fermented diet (87.2 ± 0.61%), rumen-fluid-molasses fermented diet (86.1 ± 0.61%) and yeast-molasses fermented diet (85.3 ± 0.61%). Besides the control diet, the latter three diets also revealed the best growth rate, feed conversion ratio, protein efficiency ratio and production profitability. In conclusion, rumen-fluid, yeast-molasses, and rumen-fluid-molasses fermentation methods improved the nutritional value of cassava leaves. Diets with 30% protein from soybean cake replaced by rumen-fluid, rumen-fluid-molasses and yeast-molasses fermented cassava leaves had overall acceptable growth performance with better production outcomes for Nile tilapia farming.
PubDate: 2024-08-24
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- Transcriptome analysis of hepatopancreas revealed the role of autophagy
under nitrite stress in Pacific white shrimp (Penaeus vannamei)-
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Abstract: Abstract Nitrite constitutes a significant pollutant that impedes the growth of P. vannamei. Conventional treatments are primarily geared toward decreasing nitrite concentrations from an environmental standpoint. Nevertheless, investigating methodologies to enhance the ability of Pacific white shrimp to withstand nitrite-induced stresses on an individual basis remains an unexplored topic. The present study examines the impact of autophagy on Pacific white shrimp’s response to high nitrite environments through rapamycin injection. The research findings indicate that activating autophagy can effectively enhance the survival rate of Pacific white shrimp under high nitrite conditions. Additionally, total hemocyte count (THC) results in the hemolymph demonstrate that autophagy can alleviate the reduction in blood cell count caused by nitrite stress. The transcriptome results show that upregulation of 718 genes and downregulation of 1071 genes after nitrite stress. The majority of these differentially expressed genes (DEGs) were related to physiological processes, including oxidative stress, energy metabolism, and lysosomes. In addition, there were 911 upregulated genes and 713 downregulated genes upon activation of autophagy. These DEGs are associated with immune responses, specifically involving glutathione metabolism, drug metabolism-cytochrome P450, and metabolism of xenobiotics by cytochrome P450, lysosomes, autophagy, phagosomes, melanization, and MAPK signaling pathways. These pathways can reduce oxidative stress and promote the metabolism of harmful substances in the body, in shrimp, thereby improving their survival rates. These findings provide new insights for research aimed at enhancing nitrite tolerance in Pacific white shrimp.
PubDate: 2024-08-23
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- Stocking densities of Colossoma macropomum in the initial grow-out phase
using biofloc technology-
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Abstract: Abstract The objective was to identify the best stocking density in the initial grow-out phase of tambaqui (Colossoma macropomum) using biofloc technology (BFT) and evaluate the effects of the densities on water quality, zootechnical performance and the metabolic profile of fish and production costs. Juveniles (56.5 ± 1.69 g) were reared in the densities: 15 (BFT15), 30 (BFT30) and 45 (BFT45) fish.m−3, in triplicate, for 80 days. The use of BFT inoculum at the beginning contributed to the maintenance of adequate ammonia and nitrite concentrations at all densities, though with a higher nitrite concentration in BFT45. Electrical conductivity (EC), nitrite, total suspended solids (TSS), pH, alkalinity and hardness were different (p < 0.05) between BFT15 and BFT45. EC and TSS increased according to the increase in density, and were higher in BFT45. The highest final weight and specific growth rate were observed in BFT15, while the apparent feed conversion was lower for BFT15 and BFT30 compared to BFT45 (p < 0.05). Biomass and productivity were higher (p < 0.05) in BFT45. The values of hematocrit, number of erythrocytes and the hemoglobin concentration were higher in BFT45 (p < 0.05). Regarding production costs, the highest average feed expenditure occurred in BFT45; however, expenditure with electricity was lower at this density. The increase in biomass in BFT45 generated the reduction of the partial average cost (ACp). It can therefore be concluded that the best stocking density for initial grow out of tambaqui is 45 fish.m−3, since it presents better productivity and biomass, lower ACp and average expenditure on electricity when using BFT.
PubDate: 2024-08-22
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- Camel whey protein hydrolysate diet mitigates alkaline stress–induced
biochemical disorders and restores the target of rapamycin, MAPK pathway,
and autophagy-related gene expression in Nile tilapia-
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Abstract: Abstract Exposure to alkaline stress is common in aquatic practices. The present research investigated the detrimental impacts of rearing Nile tilapia under alkaline water stress by investigating the liver function indices and transcriptomic profile. A 30-day study was conducted on 160 fish (16.02 ± 0.14 g) split into four groups, each with four replicates. Group 1 (G1) and G2 were fed on a basal diet fortified with 0 and 75 g/kg diet camel whey protein hydrolysates (CWP) and reared in freshwater (carbonate alkalinity = 1.4 mmol/L, pH = 7.19). Moreover, G3 and G4 were fed on a basal diet enriched with 0 and 75 g/kg diet CWP and reared in alkaline water (carbonate alkalinity = 23.8 mmol/L; pH = 8.65). The outcomes revealed elevated lipid indices (triglycerides, cholesterol, low- and high-density lipoproteins) and liver enzymes (alanine and aspartate aminotransferase, alkaline phosphatase, and gamma-glutamyltransferase) with lowered protein indices (total protein, albumin, and globulin) in alkaline-reared fish. Moreover, oxidative stress was initiated through lowered antioxidant enzymes (superoxide dismutase, catalase, and reduced glutathione) and higher malondialdehyde in the alkaline-exposed fish. Alkaline stress induced the activation of the mechanistic target of rapamycin and MAPK pathway (mitogen-activated protein kinase, c-Jun NH terminal kinase, and MAPK-1) with down-regulation of the autophagy-related genes (ATG-5, ATG-7, and ATG-13) and cathepsin B expression. Feeding on a CWP-supplemented diet resulted in significant modulation of the lipid profile, liver enzyme activity, and improvement in protein indices and antioxidant enzyme activity. Furthermore, modulation of the transcriptomic profile of the hepatic tissue of the alkaline-exposed fish was noticed due to feeding on a CWP-supplemented diet. Overall, CWP dietary addition at a level of 75 g/kg diet can alleviate the alkaline stress exposure in Nile tilapia. These outcomes could contribute to understanding the physiological circumstances of Nile tilapia when reared in alkaline water as well as provide a novel dietary additive for mitigating the bad consequences due to alkaline-stress exposure.
PubDate: 2024-08-21
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- A comprehensive study on nutritional quality, physiological enzyme
activity and genetic diversity in six populations of Penaeus monodon-
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Abstract: Abstract Penaeus monodon is a crucial economic crustacean globally and a focal point of aquatic research. Germplasm resources provide a diverse food source for humans, meeting various nutritional needs; they also maintain plant and animal gene banks, enhancing resilience, adaptability, and promoting ecological balance in terms of genetic diversity. To accurately assess the germplasm resources of P. monodon, we conducted a comprehensive investigation. We analyzed muscle characteristics, nutrient content, amino acids, fatty acids, and genetic diversity using whole-genome sequencing in six P. monodon groups. The results showed that the crude protein content of the six groups of P. monodon was 21.17–24.60 g/100 g, crude fat content was 0.60–0.80 g/100 g, essential amino acid content was 5.44–6.41 g/100 g, total amino acid content was 15.68–18.63 g/100 g, and total fatty acid content was 354.78–587.43 mg/100 g. Genetic differentiation index (Fst) values ranged from 0.029 to 0.604 for six groups. PmSZ has a good genetic condition. There was no significant difference in crude fat in conventional nutrients, and the difference in biochemical indexes T-AOC, CAT, and SOD was not significant (P > 0.05). The noteworthy point is that the analysis of genetic diversity reveals a moderate level of genetic diversity. PmDF and PmZH exhibit the highest degree of differentiation, while PmRP and PmZH show the lowest degree of differentiation. Our survey results establish a critical foundation for comprehending and harnessing the germplasm resources essential for selectively breeding robust P. monodon populations.
PubDate: 2024-08-20
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- Acceptance of farmed African catfish in Egypt: addressing consumer
concerns and marketing challenges-
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Abstract: Abstract African catfish farmers used animal waste as feed to reduce production costs, a practice that raised concerns among consumers, causing them to avoid it. Consequently, this study aimed to explore factors that influenced the acceptance of farmed African catfish. The data survey involving 2294 participants from Egypt was analyzed using descriptive statistics and the chi-square test. The results indicated that 67% of participants abstained from consuming it, while 2.30% consumed it regularly. The chi-square test revealed significant consumption pattern variations (p < 0.05) based on most demographic factors. Entirely, 43% were uninformed about the nutritional value, market availability, and the potential impact of using aquafeeds on pricing. About 55–57% lacked information on feeding practices, had quality concerns, viewed catfish consumption as a health risk, and were unaware of its prices. Additionally, 68% were worried about pollution, and 76% found the available information insufficient. The main reasons for this challenge lie in consumers’ health, religious, and psychological concerns. To address this, we propose a targeted marketing strategy focusing on improving safety and quality through safe and cost-effective aquafeeds. This involves requiring farmers to obtain quality certifications and adhere to best management practices, adding value to the product, and transparent communication with consumers to provide them with reliable information about cultivation practices and the nutritional value of African catfish. Effective collaboration among key stakeholders in implementation, efficient sector management, establishing an activity licensing system, and prohibiting current feeding practices will enhance sustainable demand and reverse the declining production trend of this promising species.
PubDate: 2024-08-20
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- Evaluation of Azadirachta indica leaf extracts efficacy against gill
flukes parasites with a focus on oxidative stress, pathological changes,
and immune gene response in infected Nile tilapia-
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Abstract: Abstract The present study evaluated the parasite activity of aqueous extracts (AE) of neem leaves (Azadirachta indica) on parasitized Nile tilapia (Oreochromis niloticus). Concurrent infection with Dactylogyrus sp. and Centrocestus formosanus metacercariae was observed after clinical and parasitological investigations. A 240 Nile tilapia fish represented the four groups in the experimental design. They were used to assess the efficiency of aqueous extracts (long bath, 7 days) against parasite-infested fish: the group without A. indica extract (control, T1), T2 (1.0 g/L), T3 (2.0 g/L), and T4 (3.0 g/L). Results revealed that neem extract groups reduced the mean intensity of parasites (Dactylogyrus sp., C. formosanus) more than the control group partially at T4 (3.0 g/L). Fish exposed to neem leaf extracts showed significant downregulation of inflammatory and pro-inflammatory and immune genes (IL-1ß, IL-8; IL-10, Cox-2, lysozyme, C3, and HSP70) along with a significant increase in antioxidative genes (SOD and CAT) partially at T4 (3 g/L). Histological examinations of fish liver and gill tissues exposed to neem extract showed a return to normal histoarchitecture, especially at T4. However, antioxidant (CAT and GSH) activities increased in gill and liver tissues exposed to A. indica extract, especially at T4. Compared to control fish, the MDA levels decreased significantly in fish treated with A. indica extract, partially in the T4 group. Immune indices (complement 3, nitric oxide, and lysozyme activity) of infected fish treated with A. indica leaves extract displayed the highest value compared to the control one, especially at T4. The study assumed that an aqueous extract of A. indica inclusion at the rate of 3.0 g/L in a long-term bath is recommended to increase the resistance against parasitic infection and improve Nile tilapia’s health welfare.
PubDate: 2024-08-20
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- Denitrification characteristics and potential application of a novel
aerobic denitrifying bacterium, Pseudomonas plecoglossicida, isolated from
the Exopalaemon carinicauda pond-
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Abstract: Abstract The excessive accumulation of nitrogen during aquaculture can cause water eutrophication, leading to serious environmental problems. Biological denitrification is an effective solution. The strain JW1, with high aerobic denitrification activity and high homology with Pseudomonas plecoglossicida, was isolated from the Exopalaemon carinicauda pond. Further study of strain JW1 revealed that it was Gram-negative and rod-shaped. The optimal conditions for growth and nitrogen removal were a C/N ratio of 10, a temperature of 28 ℃, a shaking speed of 150 rpm, and a salinity of 7.5. With NH4Cl or KNO3 as the sole nitrogen source, the removal rates of NH4+-N or NO3−-N were 97.8% or 97.9%, respectively; with NH4Cl and KNO3 as mixed nitrogen sources, the removal rates of NH4+-N and NO3−-N were 98.8% and 98.9%, respectively; and the accumulations of NO2−-N were trace in all treatments. Strain JW1 had no hemolytic activity and was sensitive to most antibiotics. After 28 days of E. carinicauda application, the cumulative mortality (28.9%) and nitrogen concentration (1.24 mg/L of NO3−-N, 0.49 mg/L of NO2−-N, and 0.15 mg/L of NH4+-N) in the JW1 group significantly were lower than those in the control group (P < 0.05). The results revealed that strain JW1 was a high-performance and biosafe aerobic denitrifying bacterium, and provided a foundation for the healthy farming of shrimp.
PubDate: 2024-08-20
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- Exploring the toxicity of chromium on aquatic ecosystems: a comprehensive
assessment of growth, physiological responses, genotoxicity, and
histological alterations in Etroplus suratensis (Bloch, 1790) juveniles-
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Abstract: The study was conducted to assess the effect of chromium on Etroplus suratensis, pearl spot juveniles under acute and chronic exposure. A 96-h acute toxicity test was conducted with eight Cr concentrations (30, 35, 40, 45, 50, 55, 60, and 65 ppm) and control. Behavioural changes such as hyperactivity, an unbalanced state, excessive mucus secretion, and an elevated rate of opercular activity were observed during the exposure. The LC50 value at 96 h was found to be 41.83 mg/L. Histological alterations in the gills and liver tissues were observed to be severely degenerative with the increase in chromium concentration. Following the acute toxicity study, chronic toxicity study was conducted for 45 days. For chronic toxicity study, three sublethal concentrations of Cr such as one-tenth of LC50 (4 mg/L, T1), one-fiftieth of LC50 (0.8 mg/L, T2), and one-hundredth of LC50 (0.4 mg/L, T3) were chosen for 45-day exposure. Significant reduction in average weight gain and specific growth rate was observed at T1 (4 mg/L) exposure. Antioxidant enzymes—SOD and catalase in the liver and gills, LPO, enzymatic parameters—glucose, AST, and ALT, and immune parameter—myeloperoxidase activity were also significantly higher at T1 followed by T2 and T3 depicting the stress response at higher chromium exposure similar to the growth and haematological attributes. Enzymatic parameters such as AChE, antioxidant enzymes like GST and GPx, and immune parameters, RBA and LYZ, have significantly decreased levels at T1, followed by T2 and T3, indicating the presence of toxicants in the environment, which caused severe damage to the cellular function. The genotoxicity assay carried out using gills revealed that the DNA damage increased in a concentration-dependent manner, in which the least genotoxic group was negative control, followed by T3. The present investigation revealed that chromium content in freshwater should be less than (0.4 mg/L) one-hundredth for Etroplus suratensis farming. Graphical
PubDate: 2024-08-19
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- Gut health improvement as a result of dietary supplementation of
VILIGEN™ in juvenile Nile tilapia-
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Abstract: Abstract This study aimed to evaluate the inclusion of VILIGEN™, a blend containing sodium butyrate, dehydrated hydrolyzed yeast, and zinc proteinate, on the profile of the allochthonous intestinal microbial community, the activity of digestive enzymes, and the integrity of the intestinal barrier of juvenile Nile tilapia, Oreochromis niloticus. A feeding trial was conducted with five VILIGEN™ doses (0.00, 0.60, 1.20, 2.40, and 4.80 g kg−1). The fish were randomly distributed into four groups per treatment, with 28 fish for experimental unit. Fish were fed to apparent satiety twice daily for 60 days. The gut medial portion was collected for enzyme activity and morphological analyses, while feces samples from the same gut portion were sampled for microbial characterization. Morphological indexes and structure of the intestinal physical barrier were determined by scanning and transmission electron microscopy. The tight junction proteins were quantified by western blot. Fish-fed diets containing VILIGEN™ showed the greatest alpha diversity and abundance of the phyla Actinobacteria and Proteobacteria and the genera Legionella, Aquisphaera, Bacillus, and Gordonibacter. Trypsin activity was higher in the gut of fish-fed VILIGEN™ supplemented diets. Regarding the greatest intestinal tissue integrity, fish-fed diets containing 2.40 g kg−1 VILIGEN™ showed the lowest fusion of the gut folds and the highest development and microvilli height. VILIGEN™ showed beneficial effects for Nile tilapia gut health, presented a positive modulatory effect on the morphology and integrity of the intestinal epithelium, increased trypsin activity, and modulated gut microbial community, including high alpha diversity of bacterial species in the gut.
PubDate: 2024-08-17
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- Scientific knowledge of the Cinnamon River prawn Macrobrachium acanthurus
and future perspectives for aquaculture-
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Abstract: Abstract The cinnamon river shrimp (Macrobrachium acanthurus) is distributed along the Atlantic Ocean, from the United States to Brazil. This species represents important resources for local communities of fishermen, but natural populations are facing a progressive decline. For several years, the aquaculture supplementation of this species has been suggested as an alternative to fisheries. M. acanthurus presents several characteristics that make it a suitable species for aquaculture, such as resistance to changes in environmental conditions, reproduction all year round, high fecundity, low aggressivity, and disease resistance. Despite this, the development of culture is, at best, at the stage of research and has been related to the difficulty of the larval stage rearing. Considering this, the review presents the actual knowledge regarding the environmental and biological conditions of M. acanthurus that might help to advance its culture. The information is presented in several parts, which include the species description, environmental conditions, reproduction, larvae and juvenile stages, culture experience, and diseases. Finally, some considerations are given to cover the gaps in the knowledge that are required to be researched.
PubDate: 2024-08-17
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- Assessment of mycotoxins found in farmed fish feed
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Abstract: Abstract Filamentous fungi, mainly those belonging to genera Aspergillus, Fusarium, and Penicillium, the main producers of mycotoxins and responsible for food and feed contamination, exhibit metabolites that are highly toxic to animals and humans. This scoping review compiles data on occurrence of mycotoxins in fish feed, assesses distribution of metabolites across continents by the hierarchical cluster analysis, and establishes risks posed to the main global orders of farmed fish by exposure to mycotoxins. Resulting data showed that fish of different orders in both fingerling and juvenile phases are exposed to high concentrations of mycotoxins.
PubDate: 2024-08-15
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- Evaluation of low-fish meal diets containing animal byproducts and plant
protein sources for juvenile olive flounder Paralichthys olivaceus-
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Abstract: Abstract This study aimed to assess the effectiveness of low-fish meal diets (LFMD), incorporating animal (tankage meal, tuna byproduct meal and poultry byproduct meal) and plant (soy protein concentrate and wheat gluten meal) protein sources as a fish meal (FM) replacement in juvenile olive flounder Paralichthys olivaceus. A control diet (FM70) was prepared to contain 70% of sardine and anchovy FM (1:1, v:v). Six experimental diets were formulated reducing FM levels in FM70 diet down to 35, 30, 25, 20, 15 and 10% (designated as FM35, FM30, FM25, FM20, FM15 and FM10, respectively) with increasing proportions of animal and plant protein sources. Fish (initial mean body weight: 22.3 ± 0.01 g) were fed each experimental diet for 12 weeks. At the end of the feeding trial, growth performance, survival and biological indices were not affected by dietary FM levels. Feed utilization was significantly decreased in FM15 and FM10 groups than in FM70 group. The gene expression of tumor necrosis factor-α (TNF-α) was significantly upregulated in FM10 group compared to FM70 group. In muscle fatty acid profiles, a reduction in palmitoleic, eicosapentaenoic and docosahexaenoic acids was observed, while oleic and linoleic acid levels increased with the decrease in dietary FM levels. These results indicate that the combined use of animal and plant protein sources would be a good option as a FM substitute for juvenile olive flounder. Considered with the decrease in feed utilization and upregulation of TNF-α gene expression, the dietary FM levels could be reduced only down to 20%. These results could be helpful to research the alternative sources of FM substitutes in feed formulations for carnivorous fishes.
PubDate: 2024-08-14
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- Beneficial microorganisms for the health-promoting in oyster aquaculture:
realistic alternatives-
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Abstract: Abstract The coexistence of various microorganisms in ecosystems establishes a dynamic balance in which various beneficial and antagonistic interactions can be observed. However, the use of intensive agricultural methods in food production can disturb this balance. Therefore, active actions are needed to prevent damage to the ecosystem, which can also harm human health. There is no doubt about the role of beneficial microorganisms, which were studied for several decades (e.g., lactic acid bacteria, spore-forming bacilli, yeasts, bacteriophages, etc.) and, based on the acquired knowledge, utilized to improve the microbiological safety across the food production and consumption chain. These microorganisms have been in practical use for quite some time and many of them are recommended under the concept of sustainable food production. Oysters have always been valued for their gastronomic qualities and were considered a symbol of culinary luxury of the gastronomic heritage. Nowadays, we see a rapid and significant increase in oyster production and consumption. However, because of the specifics of production, distribution, and consumption, the safety of this food product is a sensitive issue that requires more attention and innovative approaches to improve farm-to-fork safety. Selecting specific natural-derived biopreservatives and health-promoting microbial-based approaches can be an attractive option for oyster production. This critical review aims to discuss the principal pathogens associated with oyster farming and realistic alternatives for controlling diseases and improving food safety, including probiotics, antimicrobial peptides, microbial metabolites, vaccines, and bacteriophages. Moreover, this review focuses on the microbiological aspects of oyster culture and evaluates the selection and application of host-specific probiotics and postbiotics.
PubDate: 2024-08-13
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- Design and research of the spindle-shaped fish vaccine adsorption
injection device-
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Abstract: Abstract Aiming at the problem that inserting a needle into the abdomen of spindle-shaped fish can easily damage the internal organs during vaccine injection, this paper takes grass carp as the experimental object and designs a fry adsorption injection device. Through theoretical analysis, the key factors affecting the adsorption force are determined. The internal cavity of the adsorption block is simulated and optimized under the given boundary conditions. The single-factor test shows that the H-shaped suction head has the best adsorption effect. Further orthogonal experiments found that the height of the adsorption port, the adsorption port’s length, and the diameter of the adsorption port are important factors that affect the test results, and they are arranged in descending order of their importance. The optimal parameter combination is the adsorption port height of 3 mm, adsorption port length of 15 mm, and adsorption pore diameter of 3 mm. Under these parameters, the success rate of needle insertion is 98%, and the survival rate of fry is 100%, which can meet the production requirements. In summary, the adsorption and injection device is simple in design, easy to operate, and can significantly reduce the damage to the fish body. It provides an effective solution and design reference for fish vaccination.
PubDate: 2024-08-13
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- The effect of protein to lipid ratios on growth, digestibility, and feed
utilization of striped bass (Morone saxatilis) raised in seawater at
21 °C-
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Abstract: Abstract A 12-week feeding trial assessed the impact of protein-to-lipid ratios (P:L) on the growth, feed and protein utilization, digestive enzyme activity, and fillet composition of juvenile striped bass (Morone saxatilis) raised at summer local seawater temperature conditions (21 °C). A 3 × 2 factorial design, using three protein levels (40, 44, and 48%) and two lipid levels (12 and 16%) resulting in six diets (40:12, 44:12, 48:12, 40:16, 44:16, and 48:16) was used. Hatchery-reared fish with an initial weight of 11.4 ± 0.2 g were used. Laboratory-formulated experimental diets were randomly assigned to triplicate groups of 22 fish in 500-L tanks connected to a recirculating seawater (35.4 ± 3 ppt) system, and fish were fed manually to apparent satiation four times a day. Survival rates were higher than 96% across all treatments, remaining unaffected by dietary treatments. Fish fed the 44:12 and 48:12 diets resulted in significantly higher weight gain (WG) (274.1 ± 18.4 and 306.8 ± 19.8, respectively), final body weight (FBW) (42.4 ± 1.2 g and 47.1 ± 2.4 g, respectively), and specific growth rate (SGR) (1.6 ± 0.06 and 1.7 ± 0.06, respectively). Diets with 12% lipid resulted in feed conversion rate (FCR) values closer to 1, and the 48:16 (1 ± 0.03) treatment resulted in no significant differences compared to the 12% lipid dietary treatments. Similar trends were observed for protein efficiency ratio (PER), with comparable values for the 40:12 (2.0 ± 0.1), 44:12 (2.2 ± 0.1), 48:12 (2.0 ± 0.1), and 48:16 (2.1 ± 0.1) treatments. A strong relationship between dietary P:E ratios and SGR, PER, and FCR was observed among treatments, which helped explain the interactions between protein and lipid obtained. An estimated dietary P:E ratio between 11 and 12 is suggested for efficient protein and feed utilization for this species under our culture conditions. The apparent digestibility coefficient (ADC %) was significantly higher in the 12% lipid diets (65.01 ± 3.06%), influenced solely by lipid content. Enzyme activity for trypsin and chymotrypsin in the pyloric caeca (PC) and intestines (I) were higher in the 48:12 treatment (893.5 ± 18.1, 1087.3 ± 55.5, 12.2 ± 0.3, and 8.3 ± 0.2 Units/g organ, respectively). L-aminopeptidase activity (PC) was higher in the 48:12 treatment (1007.7 ± 101.8 Units/g organ), while L-aminopeptidase (I) had higher values in the 48:16 treatment (2217.2 ± 161.3 Units/g organ). In the case of lipase (PC), activity was higher in the 12% lipid treatments, while in the intestine, the highest activity was recorded in the 44:12 treatment (1084.4 ± 87.0). The activity of proteases, except for L-aminopeptidase (PC), directly correlated with improvements in SGR, PER, feed intake (FI), and FCR which helps explain the observed results. The Hepatosomatic index (HSI) was significantly higher in the 40:12 treatment while the liposomatic index (LSI) and viscerosomatic index (VSI) indices showed no significant differences between the 40:12, 44:12, 48:12, and 48:16 treatments, respectively. Importantly, the lipid content in the fillet did not significantly decrease with reduced lipid content in the diet, an important issue for market acceptance. Results from the present study suggest an optimal P:L ratio of 48:12 for juvenile striped bass raised in seawater under local summer conditions (21 °C).
PubDate: 2024-08-12
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- Biofloc technology (BFT) improves the productive performance and survival
rate of Salminus brasiliensis-
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Abstract: Abstract The aim of this study was to evaluate the productive performance and survival rate of dourado (Salminus brasiliensis) in biofloc technology (BFT) and in a traditional system with 20% water renewal per day. The design was completely randomized with two treatments and four replications. The experimental units were composed of aquariums with a useful volume of 50 L and constant aeration, with 20 fish (4.12 g; 6.25 cm) allocated in each. In treatment with the traditional system, 10 L of water was siphoned from the aquariums every day during the 28 days of the experimental period. Water quality, productive performance, survival, and body score analysis for injuries were evaluated. Better water quality was observed in the BFT production system. No significant differences were observed at the end of the experiment for average weight, length (standard and total), daily weight gain, and specific growth rate. The results of feed conversion ratio, final biomass, and biomass gain were better (P < 0.05) for fish in BFT (1.44; 155.33 g; and 72.88 g/day) compared to the traditional system with partial water renewal (1.84; 128.1 g; and 45.5 g/day). Survival and body score analysis for injuries were better (P < 0.05) in fish maintained in BFT. In conclusion, the BFT production system provides a decrease in aggressiveness, better production performance, and survival rates and thus is more suitable for S. brasiliensis production in the initial phase compared to the traditional system with partial water renewal.
PubDate: 2024-08-10
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- Effects of nitrite exposure on biochemical parameters and liver
histopathology in American bullfrogs (Aquarana catesbeiana)-
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Abstract: Abstract Nitrite one of the most common contaminants affecting aquatic species. In this study, we investigated the biochemical markers and histopathological changes in the liver of the American bullfrog (Aquarana catesbeiana) exposed to nitrite at different concentrations (0, 5, 10, and 15 mg/L) for 96 h. Results revealed that blood biochemical markers such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl transferase (GGT), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) were significantly increased in the American bullfrog groups exposed to nitrite. Additionally, there was a significant increase in the activities of antioxidative enzymes such as total antioxidant capacity (T-AOC), superoxide dismutase (SOD), lactate dehydrogenase (LDH), and glutathione S-transferase (GST) in the liver. Furthermore, the liver tissue of bullfrogs exposed to nitrite exhibited pronounced inflammatory infiltration, increased melano macrophage density, vacuolization, and shrinkage of hepatocytes. This study provided an avenue to understand the sensitivity of the American bullfrog to nitrite, suggesting irreversible liver damage even at low nitrite concentrations (5 mg/L). The results underscore the potential harm of nitrites to bullfrogs, contributing to optimized management strategies in American bullfrog farming.
PubDate: 2024-08-09
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- Comparative transcriptome analysis reveals differential expression of
sex-related genes in androgenic glands and ovaries of Macrobrachium
rosenbergii-
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Abstract: Abstract Macrobrachium rosenbergii is an economically important crustacean worldwide. Based on the important role of the androgenic gland (AG) in sex determination in crustaceans, this study comparatively analyzed the transcriptomes of AG and ovary tissues using Illumina sequencing technology. A total of 91,810 unigenes were generated from the six libraries after splicing and assembly, and 28,516 (31.1%) were annotated by BLASTx comparison with Nr and other databases. A total of 20,793 differentially expressed genes including 105 potentially related to sex determination and sex differentiation were identified in both tissues, of which 69 were upregulated in the ovary, 19 were upregulated in AG, 12 were ovary-specific, and 5 were AG-specific. This study screened out differentially expressed genes related to sex determination and differentiation by comparing the transcriptome expression differences between the ovary and AG of M. rosenbergii, accumulating important data for further studies on the mechanisms of sex determination and differentiation in M. rosenbergii.
PubDate: 2024-08-09
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