The aim of this study was to evaluate the labeling of rosemary extract nanoparticles (RE-NPs) using 67Ga radioisotope, and their biodistribution in healthy rainbow trout (Oncorhynchus mykiss) tissues. RE-NPs were prepared by gamma irradiation (irradiated at a dose of 30 kGy of gamma-ray by 60Co (PX-30 IssIedovapel, Russia, dose rate of 0. 02 Gy sec-1) and ultra-sonication methods at two concentrations of 0. 5% and 1% and labeled by 67Ga radioisotope. Quality control studies were done using the RTLC method. The radiolabeling RE-NPs at 1% concentration showed 97% efficiency using a mixture of sodium acetate and acetic acid buffer at pH=6. 5 after 30 min at room temperature. In the biodistribution study, 54 healthy fish were randomly distributed into two treatment groups (n=18 fish/treatment group) and one group served as healthy control. Fish received 3. 7-7. 4 MBq (300 µL) of radiolabeled RE-NPs at 1% concentration and free 67GaCl3, intraperitoneally. The 67Ga-RE-NPs single-photon emission computed tomography (SPECT) demonstrated the highest tracer accumulation in the kidney and the least uptake in the brain at 24 h after injection of 67Ga-RE-NPs. However, 48 h after injection of 67Ga-RE-NPs, the uptake was negligible in all organs as compared to free 67GaCl3. The obtained results revealed that administration of 67Ga-RE-NPs, as a natural tracer, by IP injection can be a good imaging method to visualize and understand the whole-body, especially the kidney and spleen tissues distribution and pharmacokinetics in healthy rainbow trout.

The aim of this study was to evaluate the efficiency of polyurethane foam containing silver nanoparticles synthesized by Verbena officinalis leaf extract in controlling of Yersinia ruckeri in treatment of water tanks of rainbow trout farming. Biosynthesis of silver nanoparticles is done with 2mM silver nitrate solution and Verbena officinalis extract. To study antibacterial effects of the produced foams in vitro methods were used, including antibiogram tests on a petri dish, the diameter of inhibition and tube test at different times. Also In vivo methods were used consisting of treatment of water contaminated with bacteria in the presence and absence of fish. Results of mean of diameter of inhibition zone of foam containing 50 and 100mg of Ag-NPs on Yersinia ruckeri were 15. 33±1. 6 and 14. 83 ±0. 76mm respectively. Yersinia ruckeri was completely removed after 2h contact with foams of 50 and 100 mg Ag-NPs in water treatment without fish, and after 10min in test tubes at different times. Antibiogram tests showed no colonies in 50 and 100mg Ag-NPs at the bottom of the foam. Water treatment in the presence of fish showed a significant reduction in density of bacteria after 48h contact with filters containing 50 and 100mg silver nanoparticles. Results of this study, as a new production of nano-biofilter, can be used to reduce and control Yersinia ruckeri bacteria in rainbow trout fish farms.

This study aimed to examine the quality changes of rainbow trout (Oncorhynchus mykiss) caught from the farm and live supply center at different times. Rigor mortis, ATP-related components, K-value, and blood parameters of rainbow trout were monitored during storage in the live supply center of rainbow trout. The progress of rigor mortis was accompanied by an increase in storage hours. The initial K-value of fish in live storage was lower than 8%. K-value of the fish climbed to more than 50% at 24 h. After 28 h, K-value of the fish increased to 73% and gradually increased till the end. The K1-value, G-value, P-value, and Fr-value were increased during storage time. The initial glycogen content in the individuals from the farm and live storage were 1. 37 and 1. 33 mg/g muscle. Significant differences in the plasma cortisol concentration were found in the fish after 24 and 72 h live storage compared to the fish caught from the farm. The L* (lightness) value of the fish fillet from the farm, 24 h, and 72 h live storage was determined as 62. 33, 58. 12, and 56. 21, respectively. After transporting the fish into the live seafood supply center, the total viable count was increased from 2. 55 to 4. 29 and 5. 63 log CFU/ g. These results suggested that the measurement of quality indexes has a great potential for predicting the freshness of rainbow trout during live storage in seafood supply centers.

Yersinia ruckeri (Y. ruckeri)-associated disease remains a problem in fish farming, despite widespread vaccine use. Y. ruckeri is still one of the main causes of economic loss in the aquaculture industry. In this study, we developed outer membrane vesicles (OMV) as a new antigen and compared its efficacy with the classical antigen (whole-cell bacteria). Rainbow trouts were immunized with Y. ruckeri-derived OMVs and formalin-inactivated whole-cell bacteria by immersion route. The fish were then subjected to an intraperitoneal challenge with live bacteria during 2-10 weeks post-immunization. Subsequently, relative percentage of survival (RPS), antibody titer, lysozyme serum activity, lymphocyte percent and kidney pathological signs were evaluated. The OMV morphology was confirmed by electron microscopy. OMV and whole-cell bacteria immunized fish had higher RPS relative to the control group, but whole-cell bacteria resulted in higher RPS than the OMV group. Moreover, in the whole-cell bacteria group antibody titer was higher than the control and OMV groups. Lymphocyte percentage and lysozyme level in the whole-cell bacteria group was increased compared to OMV and control groups. Y. ruckeri's pathological damage was observed in the control group, while only eosinophilic secretions were identified for both immunized groups. These findings proved the protection of Y. ruckeri-derived OMV against Y. ruckeri, but whole-cell bacteria in the immersion method had a better effect on disease protection.

Introduction: Essential oils are used as flavoring agents in various foods. Layer-by-Layer (LBL) technique is a method in which the material is dipped into a series of different solutions containing oppositely charged polyelectrolytes. The aim of this study is to investigate the effectiveness of a multilayered edible coating with an antimicrobial compound (Lemon and Peppermint) in enhancing the quality and shelf-life of rainbow trout (Oncorhynchus mykiss) during refrigerated storage (4 ± 1˚C) over a period of 16 days. Methods: In this study, multilayered coating was used with two concentrations of Lemon (LEO) and Peppermint (PEO) essential oils (0.5 and 1%). Antibacterial effect of these treatments was evaluated by enumeration of bacteria in special culture media. The control and the coated fish samples were analyzed periodically for pH and microbiological (total viable count, psychrotrophic count, lactic acid bacteria, Enterobacteriaceae, and coliform) characteristics. Results: The results obtained in this study demonstrate that multilayered coating in combination with Lemon and Peppermint essential oils can significantly decrease the number of bacteria and delay the spoilage of the samples (p<0.05). Conclusion: Multilayered edible coating with an antimicrobial compound can properly delay the growth of spoilage microorganisms and prolong the shelf life of meat products.

The objectives to this research were to determine the haematological changes in Oryctolagus cuniculus as an animal model in response to killed hemorrhagic septicemia virus (VHSV) virulent to Oncorhynchus mykiss. This study composed of 5 groups; Treatment 1 (T1) with 1cc virus, treatment 2 (T2) with 0.5cc virus and 0.5cc adjuvant, treatment 3 (T3) with 0.75cc virus and 0.25cc adjuvant, treatment 4 (T4) with 0.25cc virus and 0.75cc adjuvant, and a control for a period of 4 months, once a month IM injection in 5 group of three New Zealand rabbits with health certification prepared by Razi Vaccine and Serum Research Institute. After 15 days, blood parameters, hematocrit (HCT), hemoglobin (HGB), mean hemoglobin concentration in red blood cells (MCH), red blood cells (RBC), average concentration of red blood cell (MCHC), white blood cells (WBC), neutrophils (SEG), lymphocytes (Lyn), eosinophil (Eos), aspirate transaminase (AST) and alanine transaminase (ALT).The results  showed that ALT, AST, HCT, HGB and WBC concentrations of all rabbits significantly were difference (p < 0.05). T2 (0.5cc virus and 0.5cc adjuvant) and T3 (0.75cc virus and 0.25cc adjuvant) showed higher ALT, AST, HCT and WBCs among other treatments in all 4 blood samplings and among these treatments, T2 with lower levels of ALT and AST (indicating less pressure on the liver) and higher levels of WBCs which can lead to greater amount of neutralizing polyclonal antibodies indicated better results.

The purpose of this study was to determine the lethal concentration (LC50-96 h) of malachite green on rainbow trout and also the histology effects of this substance on the liver, gills and kidney. With increasing concentrations of malachite green, rainbow trout mortality increased during the period of 24 to 96 hours. Twenty four hour lethal concentration (LC50-24 h) of malachite green on O. mykiss is 32.28 mg L-1. Forty eight hour lethal concentration (LC50-48 h) of malachite green is 16.32 mg L-1, and 72-hour lethal concentration (LC50-72 h) of malachite green is 2.52 mg L-1. All lethal concentrations at 72 hours showed a clear reduction compared to 24 and 48 hours. The median lethal concentration of malachite green (LC50-96 h) of rainbow trout was 0.83 mg L-1 during four consecutive days (96 hours). On the other hand, malachite green showed destructive effects on liver, gills and kidney tissue of rainbow trout, and these changes were more intense with increasing concentration of malachite green. Therefore, due to the grading of toxicity is determined by the amount of LC50-96 h and also observing tissue effects exposed to this substance, the malachite green is considered highly toxic to rainbow trout. For this reason, there are always concerns about the possibility of its transmission to consumers or humans; therefore, regarding to this matter that using this substance in the fish farms has been prohibited by Iran Veterinary Organization, it is necessary to remove malachite green from the list of drugs used in fish breeding and provide the other safe drugs.

In recent years, many studies were carried out for developing new food packaging systems. There is a variety of synthetic and natural antimicrobial compounds used to control the growth of microorganisms. The use of natural antimicrobial agents, due to the low side effects and high antibacterial potential, has captured the attention of scientists. The main aim of this study was to produce polylactic acid-based biodegradable active films containing lemon verbena Essential oil nanoemulsion to control the growth of two common foodborne pathogenic bacteria (Staphylococcus aureus and Escherichia coli) in Rainbow Trout. To aim this, the antibacterial activity (in vitro) of the films were assessed under MIC and MBC assays using the microdilution method. The nanoemulsion was prepared by ultrasonic waves. Based on dynamic light scattering, the mean droplet size was reported at about 22.4 nm. Based on the antibacterial results, the growth of both microorganisms was significantly decreased after 0, 3, and 7 days of storage in comparison with the control group (p <0.05). To sum up, the presence of Lippia citriodora Nanoemulsion in the matrix of the polylactic acid film showed notable antibacterial activity during 7 days of storage at 4˚C (refrigerator). It can be concluded that this film can be a good candidate for food packaging purposes to control the growth of microorganisms.

This study investigated the effect of Sargassum angustifolium and Gracilaria pulvinata extracts on the growth performance, body composition, antioxidant status and gut microbiota of rainbow trout (Oncorhynchus mykiss) fry. For this purpose, 540 fry of rainbow trout (initial weight 0. 23±0. 04 g) were distributed in 12 fiberglass tanks. Fish were fed with experimental diets containing 500 mg kg-1 of Sargassum extract (SA), 500 mg kg-1of Gracilaria extract (GL) and 250 mg kg-Sargassum + 250 mg kg-1 Gracilaria extract (SA+GL). The control diet was a commercial diet without seaweed extract. At the end of experiment growth and feeding performance including final weight, specific growth rate (SGR), weight gain (WG) and feed conversion (FCR) in all treatments were not significantly different (p > 0. 05). Whole body protein, ash and moisture contents of fish were not significantly affected by dietary macroalgae extracts (p > 0. 05). However, lipid content was significantly lower in fish fed of extract Gracilaria and Sargassum compared to control (p < 0. 05). The seaweed extract-fed fish utilized efficiently the body lipid and suppressed body weight loss during starvation. No significant difference (p > 0. 05) in serum total protein, creatinine alanine transaminase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP) and blood superoxide dismutase (SOD) activity were observed in all treatments. Whereas serum albumin, glutathione peroxidase (GPX) and catalase specific activity were higher in SA, GL and SA+GL treatments compared to the control group (p < 0. 05). ACH50 level was significantly (p > 0. 05) increased in GL and SA+GL treatments as compared SA and control group. The addition of Sargassum and Gracilaria extracts to feed did not affecte total bacterial population but increased lactobacillus bacteria levels (p < 0. 05) in the intestine. These results revealed the potential antioxidant enhancing and health-promoting effects of dietary Sargassum angustifolium and Gracilaria pulvinata extracts.

The role of immunostimulants in reducing diseases and enhancing fish performance has been proven in various studies. In this study, the effects of antioxidant procyanidin and commercial probiotic Bio-Aqua® on some hematological and immune indices of rainbow trout (Oncorhynchus mykiss) were investigated. A total number of 525 fingerlings in seven treatments (each treatment in triplicates) with experimental diets, including (1) commercial food without supplements (CTL), (2) 400 mg procyanidin kg-1 feed (PC400) , (3) 800 mg procyanidin kg feed-1 (PC800), (4) 0.50% probiotic diet (PB0.5), (5) 1.00% probiotic diet (PB1), (6) probiotic and procianidin 0.50% and 800 mg kg-1 feed, respectively (PB0.5 + PC800) and (7) probiotic and procianidin 1.00% and 400 mg kg-1 feed, respectively, (PB1 + PC400) were fed for eight weeks. The results showed that the use of procyanidin alone did not have any significant effect on blood biochemistry and immune indices. However, the individual use of Bio-Aqua® probiotic could affect the hematological and immune indices of fish, except for monocyte, compared to the control and procyanidin treatments. However, the combined use of the supplements improved the hematological and immune indices of fish. It was concluded that the simultaneous dietary administration of procyanidin and probiotic Bio-Aqua® could improve the general health of rainbow trout.