selenium

Polychaeta, or bristle worms, are a class of marine Annelid worms with segmented bodies. Each segment has paired fleshy appendages called parapodia, equipped with bristles known as chaetae made of chitin. Over 10,000 species are described, and polychaetes play vital ecological roles as predators and prey in their ecosystems. Polychaeta, Hediste diversicolor is one of the important live foods in fish and crustacean nutrition such as sturgeon and shrimp. This study aimed to investigate the effect of different levels of selenium nanoparticles (Se-NPs) and iron nanoparticles (Fe-NPs) on the growth and survival of H. diversicolor.

48000 Hediste worms (with an average wet weight of 37 mg) were distributed in 12 tanks (50-L volume) as a completely randomized design with four treatments and three replications (4000 worms per m2). Treatments included control (without adding nanoparticles), T1 = 50 mg/kg Fe-NPs + 0.5 mg/kg Se-NPs, T2 = 100 mg/kg Fe-NPs + 1 mg/kg Se-NPs and T3 = Fe-NPs 200 mg/kg + 2 mg/kg Se-NPs. Before starting the experiment, Hediste worms were adapted to the tank conditions for one week, and then they were fed diets containing selenium and iron nanoparticles for 12 weeks.

The results indicated that increasing the amounts of selenium nanoparticles (Se-NPs) and iron nanoparticles (Fe-NPs) in the diet significantly enhanced the biomass and survival rate of Hediste worms. Specifically, as the concentrations of selenium and iron in the treatments increased, the length of L3 (the combined length of the first three segments: prostomium, peristomium, and first chaetiger) decreased significantly. T2 and T3 exhibited shorter L3 lengths compared to the control group. The highest survival rates were observed in T2 (65.5%) and T3 (66.6%), while the greatest biomass was recorded in T3 (1514.8 g/m²). Notably, Hediste worms in the control group consumed significantly more food and displayed the highest food conversion ratio (FCR). In contrast, the lowest FCR values of 0.57 and 0.54 were recorded in T2 and T3, respectively, indicating a positive effect of these nanoparticles on improving FCR.

The combined application of Se-NPs at a concentration of 2 mg/kg with 200 mg/kg Fe-NPs demonstrated a superior effect on the growth and survival rate of Hediste diversicolor compared to both the control diet and other treatments.Conflicts of interest: Authors have no conflict of interest to declare for the publication of the present work.Acknowledgments: This research was conducted as a study opportunity for members of the faculty of the Agricultural Research, Education, and Extension Organization in Society and Industry. We would like to thank the Zist Palayeshgar Khazar Company (ZPK) and the International Sturgeon Research Institute.

Dietary Selenium (Se) is vital for the growth and immune system of fish. The most important action of Se biological functions comes from several specific selenoproteins, some of which are involved in thyroid hormone metabolism, while others play an antioxidant defence role. Se as a nutritional element is obtained in the aquatic environment from two main sources: feed and fertilizer. Fish species absorb dietary Se in various forms, such as organic and inorganic. It should be used in the correct dosage and anything above this can have negative consequences. As for Se in the diet of fish, there are a few different forms commonly used as inorganic, such as Na2SeO3 or sodium selenite. Organic forms of dietary Se also include selenomethionine (SeMet) and selenocysteine (SeCyst). This study was performed to evaluate the effect of different sources of Se on growth performance, activity of antioxidant enzymes and thyroid hormones in rainbow trout.Organic Se (Se methionine), mineral Se (sodium selenite) and nanoselenium were added to the basal diet at a rate of 0.3 mg/kg. Basal food without Se compounds was used as a control treatment. Fish with an average weight of 29.25 ± 1.70 g were fed with experimental diets for 8 weeks. The fish were fed twice a day (at 9:00 AM and 2:00 PM) at the rate of 4% of their biomass. The results showed that selenium nanoparticles had no significant effect on growth indices compared to organic and inorganic forms (p<0.05). The activities of superoxide dismutase and catalase enzymes in treatments containing different forms of Se was significantly higher than in the control (p<0.05). The level of malondialdehyde in the liver of fish fed the diet containing sodium selenite was significantly lower than the other experimental treatments (p<0.05). The amount of triiodothyronine in treatments containing selenomethionine and Se nanoparticles was significantly higher than in the control group (p<0.05), which may be due to the stimulation of thyroid stimulating hormone. Thyroxine was not significantly different in fish fed with different forms of Se and in control (p>0.05). In general, using organic, mineral and nanoselenium sources with a concentration of 0.3 mg/kg of diet has strengthened the antioxidant status of rainbow trout fry, and also through the metabolism of triiodothyronine, it has improved the function of the thyroid gland.

This study aimed to investigate the effects of different levels of selenium nanoparticles (Se-NPs) and iron nanoparticles (Fe-NPs) on histopathology of the liver in the beluga juvenile, Huso huso. A total of 135 beluga juveniles (with initial weight of 276.4 ± 32.3 g and initial length of 40.0 ± 2.0 cm) were randomly distributed in 27 fiberglass tanks at 9 different treatments with three replicates. Treatments included T1 (control, no added NPs); T2 (1 mg/kg Se-NPs); T3 (2 mg/kg Se-NPs); T4 (100 mg/kg Fe-NPs); T5 (100 mg/kg Fe-NPs + 1 mg/kg Se-NPs); T6 (100 mg/kg Fe-NPs +2 mg/kg Se-NPs); T7 (200 mg/kg Fe-NPs); T8 (200 mg/kg Fe-NPs +1 mg/kg Se-NPs); T9 (200 mg/kg Fe-NPs +2 mg/kg Se-NPs). Before starting the experiment, the fish were adapted to the rearing conditions for one week. The amount of feeding during the rearing period was 2-3% based on the weight and water temperature, and the fish were fed three times a day (8:00, 15:00 and 21:00) for 8 weeks. In order to find the histopathological changes, the livers of six fish from each group (two fish of each replicate) were sampled at the end of the experiment. Samples were dehydrated by routine methods and embedded in paraffin wax. They were sectioned by microtome and stained with H & E. Vacuolar degeneration, necrosis, inflammation, irregular hepatocytes and hemorrhage were the tissue lesions observed in the liver. Given that, T5 (100 mg/kg Fe-NPs + 1 mg/kg Se-NPs) had the lowest liver tissue damage, using 1 mg selenium nanoparticles with 100 mg iron nanoparticles in the diet of farmed beluga is recommended.

 This study was performed to evaluate the effect of immune system stimulants (vitamins E, C and selenium) on biochemical and immunity indices of Late calcarifer. For this purpose, two treatments were selected. Treatment 1 or control group was fed with food without immune stimulant and treatment 2 with diet containing vitamins E, C and selenium at 2% of the biomass weight. Finally, growth efficiency indices were compared in two treatments. Results showed final weight of the control and treatment groups was 761.33 ± 35.8 g and 850.00 ± 5.77 g, respectively. The specific growth rate of the control and treatment groups was 1.3 ± 0.02 and 1.35 ± 0.01 but the feed conversion ratio did not show a significant difference. Hemoglobin and erythrocytes showed a significant increase compared to the control in treatments containing immune stimulants and supplementation (p < 0.05). White blood cells ranged from 41417 ± 2964.84 in the treatment to 42500 ± 683.13 in the control treatment. The number of red blood cells in the control treatment was 2810000 ± 19.1763 and the recipient treatment was 3951667 ± 14588.84. Immune system stimulants including vitamins E, C and selenium can play a role in improving the growth, blood, biochemical and safety indices of farmed Late calcarifer.