Fish In Control Group Research Articles

Dietary algal-sourced zinc nanoparticles promote growth performance, intestinal integrity, and immune response of Nile tilapia (Oreochromis niloticus)

BackgroundTrace elements play a crucial role in fish nutrition, with zinc (Zn) being one of the most important elements. BIO-sourced zinc nanoparticles were synthesized using the green microalga Pediastrum boryanum (BIO-ZnNPs, 29.35 nm). 30 or 60 mg/ kg dry feed of the BIO-ZnNPs (BIO-ZnNPs30 and BIO-ZnNPs60) were mixed with the Nile tilapia (Oreochromis niloticus) basal diet and fed to the fish for 8 weeks to evaluate their impact on fish growth, digestion, intestinal integrity, antioxidative status, and immunity.ResultsA significant enhancement was observed in all investigated parameters, except for the serum protein profile. BIO-ZnNPs at 60 mg/kg feed elevated the activities of reduced glutathione (GSH) and catalase (CAT), enzymatic antioxidants, but did not induce oxidative stress as reflected by no change in MDA level. Fish intestinal immunity was improved in a dose-dependent manner, in terms of improved morphometry and a higher count of acid mucin-producing goblet cells. Interleukin-8 (IL-8) was upregulated in BIO-ZnNPs30 compared to BIO-ZnNPs60 and control fish groups, while no significant expressions were noted in tumor necrosis factor-alpha (TNFα), nuclear factor kappa B (NFkB), and Caspase3 genes.ConclusionOverall, BIO-ZnNPs inclusion at 60 mg/kg feed showed the most advantage in different scenarios, compared to BIO-ZnNPs at 30 mg/kg feed. The positive effects on growth and intestinal health suggest that BIO-ZnNPs supplementation of aquafeeds has many benefits for farmed fish.

Functional role of TrIL-1β in Takifugu rubripes defense against Cryptocaryon irritans infection

The Japanese puffer, Takifugu rubripes, is a commercially important fish species in China that is under serious threat from white spot disease (cyptocaryoniasis), which leads to heavy economic losses. We previously found that interleukin-1β (IL-1β), an important cytokine with a potential role in resistance against pathogens, was one of the most significantly differentially up-regulated proteins in the gills and spleen of T. rubripes infected by the protozoan parasite Cryptocaryon irritans. In this study, we assessed the potential function of T. rubripes IL-1β (TrIL-1β) in fish infected with C. irritans. Phylogenetic analysis indicated that the TrIL-1β protein sequence was most closely related to that of Atlantic salmon (Salmo salar) (67.2 %). The incubation experiments revealed that TrIL-1β may reduce trophont activity by destroying membranes. Immunofluorescence experiments showed that recombinant TrIL-1β promoted the expression of endogenous IL-1β, which penetrated and disrupted the cell membranes of trophonts. Transmission electron microscopy showed that the IL-1β group had less tissue damage compared with control groups of fish. IL-1β-small interfering RNA and IL-1β overexpression experiments were performed in head kidney primary cells, and challenge experiments were performed in vitro. Quantitative RT-PCR results showed that TrIL-1β regulated and activated MyD88/NF-κB and MyD88/MAPK/p38 signaling pathways during C. irritans infection. TrIL-1β also promoted the differential expression of IgM, showing that it was involved in humoral immunity of T. rubripes. The cumulative mortality experiment show that TrIL-1β could protect fish against C. irritans infection. These results enrich current knowledge about the molecular structure of TrIL-1β. They also suggested that recombinant TrIL-1β could be used as an adjuvant in a subunit vaccine against C. irritans infection, which is of profound importance for the prevention and control of parasitic diseases in T. rubripes.

DNA vaccine incorporated poly (lactic-co-glycolic) acid (PLGA) microspheres offer enhanced protection against Aeromonas hydrophila infection

Encapsulation of DNA vaccines onto carriers enhances the immunogenicity of an antigen. Specifically, biodegradable polymers offer sustained release of vaccines which is crucial for any targeted delivery approach. Poly (lactic-co-glycolic) acid (PLGA) microspheres were used to load a DNA vaccine having a targeted gene of outer membrane protein (OMP) of Aeromonas hydrophila to clone and construct a DNA vaccine using a eukaryotic expression vector system (pVAX1-OMP DNA) and delivery in Carassius auratus against A. hydrophila infection. PLGA microspheres were prepared by emulsion technique oil-in-water and characterized by a High-Resolution Scanning Electron Microscope (HR-SEM). The results of PLGA-pVAX1-OMP DNA microspheres shows that average of 100–150 μm particle size and a loading efficiency (LE) of 68.8 %. Results indicate that C. auratus fed with PLGA-pVAX1-OMP DNA microspheres revealed a significant improvement in innate immune response, which includes, myeloperoxidase activity, respiratory burst and total immunoglobulin level compared with control group fish. The immune-related gene, IL1β, IL10, TGF, c-type, and g-type lysozyme also showed significantly higher expression after immunization. Furthermore, dietary supplementation of the PLGA-pVAX1-OMP DNA (G III) group exhibited a significantly higher survival rate (78 %) than the control group of fish. These results help us to understand the of mechanism of DNA vaccine administrated feed through PLGA nanoparticles resistance to infection by regulating systemic and innate immunity in Carassius auratus.

Black Soldier Fly (Hermetia illucens) Meal as Direct Replacement of Complex Fish Feed for Rainbow Trout (Oncorhynchus mykiss) and African Catfish (Clarias gariepinus).

In the experiments, defatted black soldier fly meal reared on vegetable byproducts was used in the fry rearing of two economically important fish species, African catfish and rainbow trout. Both fish species were reared in a recirculation system and 0-33-66-100% of the complex fry feed was replaced by a defatted prepupae meal of black soldier flies during a 28-day feeding experiment. African catfish was reared at 25 ± 1 °C while rainbow trout was reared at 12 ± 1 °C. The results showed that the growth of African catfish was not significantly reduced when 66% of the feed was replaced by soldier fly meal (mean weight in the control fish group at the end of the experiment was 0.4632 ± 0.2469 g, while the 66% group resulted mean weights of 0.4150 ± 0.1886 g) and the survival did not show any statistically different results (mean survival in control group was 57.48 ± 13.76% while it was 56.6 ± 7.763% in the 66% group). In the case of rainbow trout, replacing the feed entirely with insect meal did not cause a decrease in weight gain (final mean weight in the control group was measured at 1.9640 ± 0.4154 g, while in the group consuming only insect meal, it was 1.9410 ± 0.4248 g) or in survival (in the control group 98.5%, while in the group consuming only insect meal 99.5%). All these preliminary results indicate that black soldier fly meal can be used directly as a nursery feed in fish farming as a partial or total replacement of complete feeds. The results showed that black soldier fly meal could replace 66% of the complex brood feed of African catfish and up to 100% of rainbow trout feed without deterioration of production results. Our experiments have therefore opened the way for further experiments on insect meal in larval rearing.

Saccharomyces cerevisiae supplemented diets mitigate the effects of waterborne cadmium toxicity on gilthead seabream (Sparus aurata L.): growth performance, haemato-biochemical, stress biomarkers, and histopathological investigations.

Yeast, Saccharomyces cerevisiae, has been utilized as a probiotic in aqua-feeds to promote growth and alleviate the stress in aquatic animals. On the other hand, cadmium (Cd) toxicity causes serious retardation of growth and welfare status of aquatic animals. The present study was conducted to evaluate the protective role of dietary yeast in mitigating the waterborne Cd toxicity effects on the growth, haemato-biochemical, stress biomarkers, and histopathological investigations of gilthead seabream (Sparus aurata L.). In a 3 × 3 factorial design, the acclimated fish (20-24g) were randomly distributed into nine treatments in triplicates where they were fed on 0.0% (control), 0.5%, and 1.0% of yeast along with exposure to 0.0, 1.0, and 2.0mg Cd/L for 60 days. All growth parameters and mRNA expressions of IGF-1 and GH genes as well as haematological parameters were markedly increased with the increase of dietary yeast levels; meanwhile these variables were significantly retarded with Cd exposure. Contradictory effects on the above-mentioned variables were observed with Cd toxicity. In contrast, blood cortisol, glucose, total cholesterol, and triglyceride, lactate dehydrogenase, alanine transaminase, aspartate transaminase, alkaline phosphatase, in addition to DNA fragments % were noticeably increased with Cd toxicity especially at the treatment of 2.0mg Cd/L, while decreasing with increasing dietary yeast levels. Compared with the control fish group, Cd concentrations in the gill, liver, and muscle tissues of gilthead seabream were higher in Cd-exposed treatments, especially at the treatment of 2.0mg Cd/L. Deposition of Cd in fish liver was higher than that in gill tissues but lowest Cd residue was observed in muscle tissues. No significant changes in Cd residues in fish organs were observed in yeast-fed fish with no Cd exposure. The Cd exposure negatively affected histological status of gill, liver, and kidney tissues of S. aurata; while feeding Cd-exposed fish on yeast diets lowered the Cd residues in fish organs and recovered the adverse effects of Cd toxicity. Hence, this study recommends the addition of bakery yeast (1.0%) to fish diets to improve the performance, overall welfare, and histopathological status of gilthead seabream, S. aurata.

Replacement of Dietary Crude Protein of Soybean Meal by Tobacco Leaf Protein Concentrate on Growth, Haematological and Biochemical Responses of Catfish, Clarias gariepinus

This study assessed the effects of replacing dietary crude protein of soybean meal with tobacco leaf protein concentrate (TLPC) on growth, haematological and biochemical parameters of catfish, Clarias gariepinus juveniles. The catfish (n=126, mean weight = 31.77±0.07g) were arranged in a completely randomized design with 6 treatments and 3 replicates with 7fish per experimental unit and fed for 40days. The treatments were 0, 20, 40, 60, 80 and 100% replacement levels of soybean meal with Tobacco leaf protein concentrate respectively. Diets had negative effects (p > 0.05) on mean weight gain (MWG), specific growth rate (SGR), feed conversion ratio (FCR) and protein efficiency ratio (PER) across treatments. Fish in the control group recorded highest values for MWG (51.20±0.25g), SGR (2.40±0.01) and PER (2.48±0.02). Similarly, the best value for FCR (1.03±0.01) was recorded amongst the control group of fish. With the exceptions of WBC, NEUT, LYPH and MCV, significant differences (p<0.05) were recorded in the values of Packed cell volume, red blood cells, Haemoglobin, PLT, MCHC and MCH across diets. The biochemical parameters recorded no significant differences (p > 0.05) across treatments with the exceptions of CHO, HDL and LDL. Also, significant differences (p < 0.05) were observed in the values of GSH, SOD, CAT and MDA across treatments. The poor growth performance coupled with reduced physiological activities of TLPC at different inclusion levels, confirmed that it could not favourably replace soybean meal however, TLPC enhanced the enzymatic antioxidant activities in the experimental fish, consequently improving the health status of C. gariepinus.

Integrated multi-biomarker responses in Mozambique tilapia, Oreochromis mossambicus under acute and chronic Diazinon® exposures

ABSTRACT The pesticide ecosystem impacts are very diverse, and depending on their persistence could exert their intrinsic toxicity within an acute to a chronic timeframe. This study examined the toxic effects of Diazinon on haematological and biochemical endpoints in Oreochromis mossambicus after chronic exposure. After a prior range fining test, fishes were exposed to predetermined diazinon concentrations (T1-0.906 mg/L) and (T2-1.812 mg/L) and sampled after 28 days for toxicity endpoints. In Diazinon-exposed fish, haemoglobin content, Total Red Blood Cells, Total White Blood Cells, and MCH levels were substantially lower (p < 0.05) than in the control fish group. The total blood glucose concentrations in treated fish were substantially greater (p < 0.05) than in the control group, whereas serum protein concentrations were significantly lower (p < 0.05). Observation for most biomarkers revealed patterns of decreasing values with increasing toxicant concentration and exposure duration. The integrated indices (IBR and BRI) indexes were used to provide visual and understandable depictions of toxicity effects and emphasised the relativity of biomarkers in terms of sensitivity and magnitude or severity of responses under graded toxicant exposures. In acute and chronic diazinon exposure circumstances, the analysed metrics show significant impairment to Oreochromis mossambicus.

Onion (Allium cepa) improves Nile tilapia (Oreochromis niloticus) resistance to saprolegniasis (Saprolegnia parasitica) and reduces immunosuppressive effects of cadmium

The present study investigated the protective effects of dietary Allium cepa against Saprolegnia parasitica infections and the amelioration of cadmium-induced immunosuppression in Oreochromis niloticus. Saprolegnia isolates were recovered during an outbreak of saprolegniasis in farmed O. niloticus raised in a poor aquatic environment. Isolates were identified phenotypically as S. parasitica. Results were confirmed further by ITS gene sequencing. Four fish groups were kept in water with cadmium (1.5 mg/L) and fed for 30 days on a diet supplemented with crude or alcoholic extracts of A. cepa using two concentrations (0.5% or 1%). Positive (with Cd) and negative (without Cd) control fish groups were given the basal diet. The 96 h LC50 value of Cd in tilapia was (15.1 mg/L Cd). Fish exposed to Cd showed poor growth performance parameters, abnormal biochemical measurements, impaired immunological responses, and high oxidative stress indicators. Feeding tilapia on A. cepa-supplemented diets enhanced their growth performance (WG, SGR) and improved the nonspecific immune responses (WBCs, total protein, globulins, lysozyme, myeloperoxidase, and antiproteases). The inclusion of A. cepa in the diets reduced the oxidative stress (GST, SOD) and significantly decreased fish mortality after the challenge with S. parasitica. Dietary supplementation with A. cepa reduced cadmium accumulation in fish organs and up-regulated IL-1β and IFNɣ levels. The most favorable benefits were obtained by the addition of 0.5% A. cepa extract. Our results highlight the immunostimulatory properties of A. cepa dietary supplementation for farmed tilapia and recommend its use prophylactically to control saprolegniasis and mitigate cadmium adverse effects.

HEAT SHOCK PROTEINS AS BIOMARKERS OF FISH POLLUTION

Нeat Shock Proteins (HSP) belong to the natural biomarkers, which are important indicators for animal diseases diagnostics and / or instrument of analyzing the effects on organism of the habitat deteriorating factors. The contamination of water by heavy metals has adverse effect on fish organism. Even in a small quantity, such heavy metal as lead is very dangerous. The analysis of toxic effects of the lead ions on the level of expression of such heat shock proteins as HSP60, HSP70 and HSC70 family in leukocytes, liver, brain and gills of the scaly carp was the main goal of our investigation.&#x0D; During 96 hours the fish were kept in the aqueous environment of a tank which additionally was supplemented with Pb (CH3COO)2. The control group of fish was maintained for the similar period of time under the same conditions, without lead acetate supplementation.&#x0D; Concentration of HSP60, HSP70 was determinated by the dot-blot-analysis due to application of monoclonal antibodies against heat shock proteins SAB4501464 (Sigma, USA), [5A5] (ab2787) (Abcam, USA) and [1B5] (ab19136) (Abcam, USA). Detection of immune complexes was performed by using the commercial substrate solution for alkaline phosphatase - CDP-Star (Tropix, UK). Visualization was done by using X-ray film ECL HyperFilm (Amersham, USA) and a kit for films developing (Kodak). The images were processed using the software package GelPro (Version 3.1, USA).&#x0D; The significant dose-depended increase (p&lt;0,001) in all experimental groups of HSP60 and HSP70 concentrations in leukocytes, liver, gill and brain has been detected, applying dot-blot analysis. At the same time, significant changes in expression of HSC70 protein have not been established. It is the evidence that stress-proteins are the sensitive markers of toxic effects of excessive concentration of lead.

Morphometric features of the Acipenser baerii × Huso huso hybrid against the background of the original (parent) species

Despite the rapid development of molecular genetic methods, the use of traditional morphometry for the identification of sturgeon hybrids, which has an obvious advantage when working in field or production conditions, does not lose its significance. The hybrid Acipenser baerii × Huso huso (Lenbel), which is promising for commercial cultivation, is completely insufficiently studied in this regard. The purpose of the work was to make a comparative morphometric analysis of the hybrid and parental species, as well as to determine its identifying features.Experimental and control groups of fish were obtained from producers grown on the farm. It has been established that the hybrid, according to most indicators, occupies an intermediate position between the Siberian sturgeon and the beluga. The difference with the parental species is statistically significant for 32 characters. The hybrid differs from the beluga in 23 plastic indicators out of 30, and in 4 out of 6 meristic indicators; from the Siberian sturgeon — in 18 of 33 plastic characters, and in 5 of 6 meristic ones. At the same time, the hybrid differs from both parents in 14 plastic and 4 meristic characters. In hybrids, the matroclinic effect is significantly manifested: the transgression rate with Siberian sturgeon below 67% was noted only for the width of the snout at the base of the middle pair of antennae (29.2%) and for the width of the gap of the lower lip (21.2%). The main indicators that are promising as test characters for hybrid identification are concentrated mainly in measurements of the head (O, HC, rc, rr, SRc SRr) and mouth (SO, il).

Trout growth (Parasalmo mykiss Walbaum, 1792) in different ecological conditions of water bodies in the Komi Republic

Despite the rapid development of molecular genetic methods, the use of traditional morphometry for the identification of sturgeon hybrids, which has an obvious advantage when working in field or production conditions, does not lose its significance. The hybrid Acipenser baerii × Huso huso (Lenbel), which is promising for commercial cultivation, is completely insufficiently studied in this regard.The purpose of the work was to make a comparative morphometric analysis of the hybrid and parental species, as well as to determine its identifying features. Experimental and control groups of fish were obtained from producers grown on the farm. It has been established that the hybrid, according to most indicators, occupies an intermediate position between the Siberian sturgeon and the beluga. The difference with the parental species is statistically significant for 32 characters. The hybrid differs from the beluga in 23 plastic indicators out of 30, and in 4 out of 6 meristic indicators; from the Siberian sturgeon — in 18 of 33 plastic characters, and in 5 of 6 meristic ones. At the same time, the hybrid differs from both parents in 14 plastic and 4 meristic characters. In hybrids, the matroclinic effect is significantly manifested: the transgression rate with Siberian sturgeon below 67% was noted only for the width of the snout at the base of the middle pair of antennae (29.2%) and for the width of the gap of the lower lip (21.2%). The main indicators that are promising as test characters for hybrid identification are concentrated mainly in measurements of the head (O, HC, rc, rr, SRc SRr) and mouth (SO, il).

Significance of extrinsic factors for the optimization of dietary cobalt supplementation in Tor putitora fingerlings.

Extrinsic factors play a significant role during aquaculture feed manufacturing practices. Herein, a 90-day feeding trial was designed in triplicate under controlled environmental conditions to evaluate the efficiency of different chemical forms of dietary cobalt at different dosage levels on growth performance, hematological, and immunological indices ofTor putitorafingerlings. Firstly, cobalt chloride nanoparticles (Co-NPs) and cobalt methionine chelated complex (Co-Met) were synthesized via physical and chemical methods respectively and then characterized for their size, surface morphology, and elemental composition analysis by using X-rays diffraction spectroscopy (XRD), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS). Results indicated the crystalline nature of Co-NPs with spherical shape having an average size < 20nm while Co-Met appeared as an amorphous complex with a honey-comb-like octahedral structure with an average size of 82.69nm. Afterward, a feeding experiment was executed and fish were divided into three groups, i.e., control group (CG; fed 40% crude protein diet with no mineral added), while the other two groups were fed graded levels (0.5-3mg/kg; increment of 0.5mg Co/group) of Co-NPs and Co-Met supplemented diets. Statistical analysis of results by using two-way ANOVA indicated significant (P < 0.001) effect of both chemical forms, dosage levels, and their interaction level on fish indicating a dose-dependent significant effect of different chemical forms of dietary cobalt on fish.Additionally, Co-Met supplemented group of fish at supplementation level of 3mg/kg diet showed highest growth performance, and improved hemato-immunological as compared to other experimental and control group of fish.

The optimal dietary taurine supplementation in zero fish meal diet of juvenile snakehead fish (Channa striata)

The most common alternative protein sources are plant-based proteins such as soybean meal but one of the limitations is taurine deficiency that can be especially detrimental for carnivorous fish. This study was to determine the important roles of dietary taurine on the growth performance, feed utilization and body composition of juvenile snakehead fish with an initial weight of 4.66–4.71 g/fish. Five test diets were investigated, using various taurine supplementation levels and both isonitrogenous and isoenergetic formulas: 1)control (fish meal inclusion); 2)zero fish meal diet (ZF) without taurine supplementation (T0); 3) ZF with taurine supplementation at 0.5% (T0.5); 4) ZF with taurine supplementation at 1.0% (T1.0); 5) ZF with taurine supplementation at 1.5% (T1.5). Fish were fed with five different dietary taurine levels for 60 days. Weight gain (WG), average daily gain (ADG) and specific growth rate (SGR) were higher in the control group of fish, followed by the T0.5 and T1.0 group but the lowest level was observed in fish fed the T0 and T1.5 (p < 0.05). The statistical results of Survival rate (SR), feed conversion ratio (FCR) and protein efficiency ratio (PER) were not significantly different (p > 0.05) among all experimental groups, whereas fish fed diet T0.5 and T1.0 had good trend in FCR and PER value similar to the control group. Dietary taurine might not affect on whole-body composition in juvenile snakehead fish (p > 0.0). Taurine accumulation in fish whole body and the liver both showed the increasing trends varying supplementation levels in each experimental diet. In the current study, taurine supplementation had no observable effects on the histological structures of liver and distal intestines of snakehead fish. This phenomenon indicated that the taurine supplementation at 0.5% in the plant protein-based diet (ZF) cloud be improved the growth performance and feed utilization of juvenile snakehead fish. Leading to, this is a positive sign of a possibility to reduce feed cost by completely taking fish meal out of a future commercial aquafeed for better aquaculture business sustainability.

Clues from the intestinal mucus proteome of Atlantic salmon to counter inflammation

Intestinal inflammation in Atlantic salmon was studied by profiling the intestine mucus proteome, employing iTRAQ and 2D LC-MS/MS approach. Two fish groups were fed soy saponin-containing (inflammation inducer) diets (SO and SP) and two control fish groups were fed diets devoid of soy saponin (CO and CP) for 36 days. The CP and SP diets contained a health additive. Inflammation characteristics in the intestine were milder in the SP-fed fish compared to the SO-fed fish. The SO group was characterised by alterations of many proteins. KEGG pathways such as phagosome and lipid binding were possibly affected in the SO group due to the higher abundant proteins like Integrin beta 2 precursor, Coronin 1A, Cathepsin S precursor, Vesicle-trafficking protein, and Neutrophil cytosol factors. On the other hand, the SP group had fewer altered proteins and inflammation characteristics; aminoacyl-tRNA biosynthesis and ribosome in the fish group were plausibly changed due to the higher abundance of many large and small subunit of ribosomes. Elevation of the abundance of ribosomal proteins, aminoacyl-tRNA ligases, and appropriate abundance of Glycogen phosphorylase and Glutamine synthetase could possibly alleviate intestinal inflammation.Data are available via ProteomeXchange with identifier PXD027922 and PXD029849. SignificanceIntestinal inflammation, caused by dietary factors, can be considered as a non-infectious disease. Hence, researchers are gathering clues to avert the associated health issues. The present study was conducted to infer the alterations in the intestine mucus proteome induced by a dietary health additive to counter intestinal inflammation in farmed Atlantic salmon. The reduction in the number of affected proteins and their alterations point to mechanisms evoked by the premix. Our knowledge on inflammation associated proteome in fish is limited and the present study not only highlights the changes, but also opens the possibility to avert the dysfunction of the organ through a dietary approach.

Levels Consumption of Sea Rabbit (Dolabella auricularia) Extract Microcapsule Mixed Feed in Goldfish (Carassius auratus)

This research aimed to determine the level of sea rabbit (Dolabella auricularia) extract microcapsule-mixed feed on consumption in goldfish (Carassius auratus). The extraction process was done by maceration method using a single solvent, namely ethyl acetate, while in making microcapsules, 1% of sodium alginate was used as a coating. The animals tested which used were goldfish with their size 7.56 ± 0.3 g and they were kept for 30 days. These animals tested were divided into two groups; the fish group that was fed with 7.7% sea rabbit extract and the control fish group or without sea rabbit extract microcapsules. The foods given was as much as 3% of fish body biomass in the morning and evening with protein ranging from 42-44%. The results showed that the highest absolute growth rate in feeding which had been mixed with sea rabbit extract microcapsules had a value of 3.16 g, food consumption rate was 62.84 g, the efficiency of feeding was as much as 29.49% while the value of conversion ratio of feeding was 3.39. From those results of this research, it can be concluded that the use of feed which had been mixed with sea rabbit extract microcapsules could increase the absolute growth, feed consumption level, the efficiency of feeding so that it was potential to be developed as a supplement in fish feed.

The change in heat inactivation of Escherichia coli O157:H7 after entering into the viable but non-culturable state in salted fish, Hypophthalmichthys molitrix

Many species of non-sporulating bacteria including Escherichia coli can enter into a viable but non-culturable (VBNC) state under stress conditions. In this study, the change in thermal resistance of E. coli O157:H7 after entering into the VBNC state in salted silver carp, Hypophthalmichthys molitrix, was investigated. E. coli O157:H7 was inoculated on the fish control group (TF) and on those fish with 30% NaCl (TF + 30% NaCl) at room temperature. Culturability of bacteria was determined using routine culture and colony counting on Sorbitol MacConkey agar. When bacteria were non-cultivable, the RT-PCR of 16S rRNA gene (including direct extraction and purification of RNA, DNase I treatment for removing DNA contamination, cDNA synthesis and electrophoresis of PCR products of cDNA) was used to detect VBNC E. coli O157:H7. Also, cultivable and VBNC E. coli O157:H7 were individually heat-treated at 55, 62 and 70 °C for 5 min. The samples were cooled and after 24 h, the thermal resistance of bacteria was determined through viability detection using RT-PCR of 16S rRNA gene. The culturability of bacteria was kept in fish treatment but they were non-cultivable in fish under 30% NaCl after 5 days. The positive expression of 16S rRNA in all studied treatments indicated the entering of E. coli O157:H7 into the VBNC state in fish treatment under 30% NaCl. Moreover, the RT-PCR of 16S rRNA gene showed that only VBNC forms of E. coli O157:H7 showed viability at 62 °C for 5 min which indicated the increased resistant of VBNC bacteria to the thermal inactivation. The ability of E. coli O157:H7 to enter into VBNC state in salted fish and also the increase of its thermal resistance suggest that VBNC E. coli O157: H7 can be considered as critical threat to public health and food safety.

Результати використання в годівлі коропа сорбенту у складі корму з ознаками контамінування мікотоксинами

Purpose. The aim of the work was to study certain morpho-physiological parameters of carp as a result of additional introduction of a mycotoxin sorbent to a feed with signs of spoilage. Methodology. During 2019–2020, two experiments were conducted in the laboratory. The first one included 7 groups-analogues of age-1+ Nyvky carp, 20 fish in each group, with an average weight of 22.5 g. The control group of fish was fed for 24 days with a compound feed with signs of spoilage, «Mykosorb» was additionally added to the diet of the experimental groups in the amounts of 0.05, 0.1; 0.15; 0.2; 0.25 and 0.4%, respectively. The second group included 4 groups of age-1+ fish, 12 fish in each group, with an average weight of 20.0 g. The diet of the control group was identical to that of the first experiment, and the experimental groups with the addition of 0.05, 0.075 and 0.1% of «Mycosorb», respectively. During the study, optimal conditions for keeping fish were provided. Fish after were measured and weighed at the end of the experiment and their weight gains were analyzed according to generally accepted methods in fish farming. The activity of antioxidant enzymes and the content of lipid peroxidation products depending on the composition of the diet were studied. Findings. The studies used compound feed with signs of spoilage as a result of violation of their storage technology, which identified three groups of toxins: Aflatoxin B1, Zearalenone and Deoxynivalenol. As a result of the first stage of the study, the rates of application of mycotoxin sorbent into the diet of carp at amounts of 0.05 - 0.2% were determined. At the same time, there was no clear proportional pattern of changes in the average weight of fish depending on the amount of introduction of «Mycosorb», the value increased in all experimental groups compared to the control by 0.4 – 15.2%. Muscles of age-1+ fish were found to have higher (p&lt;0,001) catalase activity after application of 0.15% of the test drug by 1.4 times, 0.2% — by 46%, 0.25% — by 69 and 0.4% — by 79%. Superoxide dismutase activity also increased, except for the groups of 0.2, 0.25 and 0.4% of «Mycosorb». There was a tendency of 21.0 and 22.6% decrease in the content of diene conjugates as a result of feeding 0.05 and 0.1% sorbent and some increase as a result of feeding 0.15; 0.2; 0.25 and 0.4% additives. Studies of the next stage showed that addition of «Mykosorb» at the rate of 0.05, 0.075 and 0.1% to the feed, the average weight of age-1+ carp in the experimental groups increased by 45.4; 37.2 and 30.3%, the condition factor — by 41.9; 40.8 and 42.7%, the relative growth rate is 4.3; 5.9 and 4.6 times, respectively. The fish body height to length ratio was lower by 10.3, 7.0 and 7.4% relative to the control group. Addition of 0.05, 0.075 and 0.1% of «Mycosorb» increased resistance of fish due to an increase in the hepatopancreatic activity of antioxidant enzymes: superoxide dismutase by 28.3, 30.5 and 5.0% and catalase by 56.5 (p&lt;0.001), 55.5 (p&lt;0.001) and 46.3% (p&lt;0.05). At the same time, addition of 0.05 and 0.1% of «Mykosorb» increased the content of diene conjugates by 11.3 (p&lt;0.01) and 12.3% (p&lt;0.01), TBC-active products by 19.7 (p&lt;0.05) and 13.2%. Originality. For the first time, the feasibility of addition of the mycotoxin sorbent «Mykosorb» into the feed with signs of spoilage was studied. The effect of feeding age-1+ carp with diets of various compositions on some morpho-physiological parameters of carp in the conditions of model tests was carried out. Practical value. Additional weigh gains and improvements of the antioxidant defense system of the carp organism were observed. The use of «Mykosorb» in carp feeding allows reducing the negative impact of low quality feed on fish body. Key words: carp, feed, feed additives, mycotoxins, sorbent, morphological parameters, growth, antioxidant defense system

Impacts of microplastics on reproductive performance of male tilapia (Oreochromis niloticus) pre-fed on Amphora coffeaeformis.

This study examines the potential defending effects of the diatom, Amphora coffeaeformis, as a feed additive versus the deleterious effects (mainly on gonads) caused by microplastics (MPs) in Nile tilapia, Oreochromes niloticus. Groups of male tilapia were pre-fed diets with four different supplementation levels of A. coffeaeformis (0%, 2.5%, 5%, and 7.5%) for 70 days, then exposed to 10 mg/L MPs for 15 days. Thereafter, samples were taken from the four experimental groups and the control fishgroup, for evaluating blood picture, erythrocytes alterations, biochemical parameters, catalase (CAT), superoxide dismutase (SDO), and total antioxidant capacity (TAC). In addition, male reproductive performance was assessed by quantifying the follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone (T), also testicular sections and GSI% were also assessed. The results showed that the number of leucocytes were significantly (p < 0.05) higher, but the number of red blood cells (RBCs), the level of Hemoglobin (Hb), the percentage of Hematocrit (Ht), the number of platelets, and the eosinophil percentages were significantly decreased (p < 0.05)when fish exposed to MPs. Biochemical parameters (ALP, glucose, uric acid, albumin, and A/G ratio) were significantly increased after MP exposure compared with the control group. Furthermore, MPs induced a significant decline in both serum LH and T levels. Testicular, histological, degenerative changes and testis-ova were found in the MP-exposed fish. Thus, A. coffeaeformis supplementation displayed ameliorative properties that detoxified the negative effects of MPs. This study provides a better understanding of the reproductive injuries caused by MPs exposureand evidence for the use of A. coffeaeformis as a natural remedy in freshwater tilapia.

Характеристика репродуктивних показників та якості статевих продуктів самиць коропа (Cyprinus carpio (Linnaeus, 1758)) за використання в годівлі голозерного вівса впродовж переднерестового періоду

Purpose. To investigate the effect of feeding carp with hulless oat during pre-spawning period on the reproductive functions of female carp as well as on qualitative characteristics of the obtained eggs. Methodology. The objects of the study were females of the Nyvky intra-breed type of the Ukrainian scaly carp breed, which were kept during the pre-spawning period in pond conditions of the State Enterprise “Nyvka” of the Institute of Fisheries NAAS of Ukraine. Females were divided into 3 groups. The first group (Experiment I) was fed with 30% hulless oat, the second (Experiment II) with 100% hulless oat. The control group of fish (Control) was fed with a grain mixture. Experiments were conducted in accordance with current methods used in aquaculture. The mass fraction of protein was determined by the Kjeldahl method, the fat content was determined by S.V. Rushkovsky method. Determination of total lipids was performed by the Folch method. Sampling of water for chemical analysis and its processing in the laboratory was carried out according to O.A. Alokin method according to the Standard of the Ministry of Agrarian Policy of Ukraine. Analytical processing of the material was performed using MS Excel. The criteria for the analysis of studied parameters were their mean values (M) and standard deviations (m). Results. According to studies, the use of 30% hulless oat in the feed of female carp during the pre-spawning has a positive effect on their production of eggs, as evidenced by an increase in relative fertility by 15.6%, fertilization rate by 4.0%, and survival of the obtained 3-day-old larvae by 5.0%. According to biochemical parameters of eggs, there was an increase in the amount of essential amino acids by 3.04 and 2.01 g/100 g of protein, and fractions of lipids responsible for energy storage, in particular triglycerides, by 11.56 and 5.62%, phospholipids by 3.65 and 2.37%, and fatty acids by 5.33 and 3.11%, respectively, according to the experimental groups. Instead, cholesterol levels decreased by 13.4 and 25.2%. Temperature, oxygen, and hydrochemical regimes in the hatchery were within aquaculture standards, except for permanganate oxidation and total iron and chlorine ions. Originality. The prospects of using hulless oat in feeding brood carp were studied in Ukraine for the first time. The analysis of reproductive parameters of female carp as a result of experimental feeding and evaluation of the qualitative characteristics of eggs and offspring obtained by the method of factory reproduction was conducted. Practical value. The results of a comprehensive assessment of aquaculture and biological parameters will provide recommendations for the use of hulless oat in feeding female carp during pre-spawning period. Key words: carp, feeding, hulless oats, reproductive parameters, survival, amino acid and lipid composition of eggs.

Characteristics of biochemical parameters of sperm production of carp sire when using hulled oats in feeding during the pre-spawning period

The restoration of freshwater aquatic life and the cultivation of highly productive sires is a key stage in the process of restoring a new generation of fish, thus, the task of increasing fertility is always relevant for the fishing industry of Ukraine. The purpose of the study is to conduct an in-depth analysis of the physiological characteristics of ejaculates of respiratory and reproductive capacity, to explore the activity of enzymes of the respiratory chain of mitochondria, to determine the percentage of sperm survival when using pre-cleaned oats, as the main component in the diet of carp during the pre-spawning period In the study, males of the Nyvka interbreed type of Ukrainian scaly carp breed were used, which were kept during the pre-spawning period in pond conditions of the State Enterprise “State Farm “Nyvka” IRG NAAS. Individuals were divided into 3 groups. The first group (Experiment I) was fed 100% hulled oats, the second (Experiment II) – 30% and the control group of fish (Control) was fed a grain mixture. The quality of male carp sexual products was assessed by determining the effect of adding hulled oats to their diet during the pre-spawning period. Indicators of sperm motility and fertilizing ability, the content of γ-, β- and α-globulins, albumin, prealbumin and physiological characteristics of ejaculates of respiratory and reducing capacity, the activity of enzymes of the respiratory chain of mitochondria (COX and SDH) were explored. Considering the increase in the productivity of fish sperm, in particular, the increase in the number of sperm with rectilinear motion, the decrease in the number of lifeless sperm and changes in the protein formula of germ cells, it was established that it is advisable to add hulled oats to the main diet in the amount of 30%. According to the results of the conducted research, it was established that the addition of hulled oats to the fodder during the pre-spawning period has a positive effect on the quantitative and qualitative indicators of male carp sexual products, the results of the research can be useful for both students and workers of the fish processing industry of Ukraine