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Aims: The present study investigated the effects of different levels using of mealworm (Tenebrio molitor L., TM) on the growth and feed performance, body composition and digestive enzymes of rainbow trout, Oncorhynchus mykiss.
Materials & Methods: Fish (8.58± 0.27 g) in a completely randomized design in 4 treatments and each with 3 replications. Rainbow trout with different levels of 0, 15, 30 and 60% diet (TM0, TM15, TM30 and TM60) (including 50% moisture) of live worm for 30 days. Data were analyzed by one-way (SPSS 17). When p values were significant (P<0.05), means were compared using Duncan's multiple-range test.
Findings: At the end of the experimental, there were significant difference between treatments in growth performance and feed utilization. The results revealed that fish growth parameters and efficiency of nutrient utilization tended to increase with increasing dietary TM levels from 0 to 60%. Feed Conversion Ratio (FCR) was significantly reduced in fish fed the diet with the highest worm level (TM60). The treatments fed TM showed highest protein and lower lipid content compared to fish fed control diet.
The analysis of gastrointestinal enzymes showed that amylase, protease and lipase had a statistically significant difference between the control and other treatments. Protease and amylase activities were found to be significantly higher for fish fed the TM60 diet compared with fish fed TM0 diet.
Conclusion: The results showed that using 60% (TM60) of worm instead of the base diet can improve growth, carcass composition and digestive enzymes.

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In the present study, the effect of phytohormone gibberellin on some physiological parameters of Tetraselmis suecica microalgae was investigated. Algae culture was performed under standard conditions with Gillard culture medium, temperature 25 ± 2 C°, light intensity 16: 8 (light/dark), salinity 25 ± 2 mg / l, and 24-hour aeration for ten days. Concentrations of 10, 20, 40, and 60 mg / l were added to the algae culture medium. Growth factors, pigments, photosynthetic factors, and biochemical composition were measured in the log phase. Based on results,  the highest rate of cell growth was observed in the treatment of 60 mg / l, although in other treatments there was a significant difference with the control (P <0.05). The highest amount of protein and carbohydrates was observed in the treatment of 60 mg / l (P <0.05). ). Total lipid content increased from 15.23 in control to 18.53 in 60 mg / l (P <0.05). Antioxidant potential, pigments, photosynthetic factors, and dry weight also showed a significant difference in the concentration of 60 mg / l compared to the control (P <0.05). The highest amount of chlorophyll a and chlorophyll b was observed at concentrations of 60 mg / l (P <0.05). Based on the results, gibberellin has a high potential for cell division, final density, antioxidant potential, cell size, and biochemical composition of Tetraselmis suecica. Also, Tetraselmis suecica can be a good candidate for marine aquatic larvae, drugs, antioxidants, and a rich source of compounds in biofuels.

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Bacteria are used directly by zooplankton as a food source. The purpose of this study is to use straw as a substrate for the proliferation of bacteria in geomembrane pools and its effects on the production and biochemical compositions of Artemia. One week before Artemia culture, the pools inoculated with Dunaliella sp. and straw (particles less than 200 microns) as follows: treatment 1= geomembrane pool containing Dunaliella sp. (one week of algae cultivation), treatment 2 = geomembrane pool containing Dunaliella sp. and 0.5 grams per liter of straw (one-week algae cultivation and adding straw from the second week), treatment 3 = geomembrane pool containing Dunaliella sp. and 0.5 g/l of straw (algae cultivation and adding straw from the first week) and treatment 4= geomembrane pool containing 0.5 g/l of straw (adding straw from the first week). Artemia was cultured for 18 days and fed based on a turbidity depth of 15 cm. The highest growth rate was observed at the end of day 18 in treatment 3 (P<0.05). The highest amount of protein was obtained in treatment 1 (P<0.05). The highest amount of biomass was observed in the control and T3 groups (P<0.05). The presence of straw in Artemia pools decreased EPA fatty acid by 5-7 times less than the control (P<0.05). Artemia can grow while feeding on environmental bacteria. Applying straw in Artemia cultivation can lead to an increase in PUFA fatty acids with 18 carbon chains.