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The probiotic effects of Saccharomyces cerevisiae and Aspergillus niger on the feeding efficiency, body composition, ammonia excretion, blood serum enzymes and the intestinal microbiota of juvenile beluga, Huso huso was investigated. The fish (31.8±2.81g) were randomly allocated into 12 oval tanks at a density of 30 individuals per tank with three replicates for each treatment,. The fish were fed either a basal diet (as control) or the diet supplemented with S. cerevisiae and A. niger (2×10⁶, 4×10⁶ and 6×10⁶ cells g^-1) for 8 weeks. The results indicated that the probiotic supplemented diet at 6×10⁶ (cells g^-1) significantly improved FCR and other nutritional indicators compared to the control treatment (p<0.05). Significant improvements (p<0.05) were also observed in ammonia excretion and blood serum enzymes between treatments. Total viable fungus and Lactobacillus spp. count were significantly improved in treatment compared to control (p<0.05). These results indicated that S. cerevisiae and A. niger improved feeding performance and blood serum enzymes of beluga.

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In a completely randomized design, the effects of two probiotic bacteria, Bifidobacterium animalis and B. lactis at four concentrations of 0 (control), 1×10⁹ (T1), 2×10⁹ (T2) and 3×10⁹ (T3) CFU 100g^-1 on nutritional parameters of rainbow trout fry (0.538 ± 0.197 g body weight) were compared for 60 days, with each treatment carried in three replications. A significant difference was observed between treatments and the control in protein and lipid gain and also body composition (p<0.05). Despite a significant difference of metabolic growth rate in T1 and T2 with T3 and the control, no significant difference was observed between T3 and the control. The results demonstrated that the use of thesebacteria could improve nutritional parameters and metabolic growth rate of rainbow trout fry.

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In a completely randomized experiment, the effect of Daphnia magna meal on growth performance and carcass composition of rainbow trout (Oncorhynchus mykiss) larvae (body weight 0.538±0.197 g) was evaluated for a period of 60 days. Five diets with the same protein content (crude protein 52.70%) were prepared, including two diets containing fermented daphnia meal T₁ (20%), T₂ (30%), two diets containing raw meal T₃ (20%) and T₄ (30%), and a basal diet without daphnia meal as the control. The bacterial species used for fermenting included five commercial probiotic species. Fermented daphnia meal brought about significantly higher growth and the lowest feed conversion ratios, viz. T₁ (1.27 ± 0.35) and T₂ (1.31 ± 0.46), in comparison with T₃ (1.38 ± 0.37), T₄ (1.41 ± 0.42) and the control (1.84 ± 0.69) (p<0.05). The result of carcass composition analyzes showed that the highest protein percentage (68.23 ± 0.48%) was in T₂ and the highest percentage of fat and energy (11.26 ± 0.50% , 4761.63 ±48.88 Cal g^-1) were in T₄ (p<0.05). The overall results of this experiment indicated that daphnia could be considered as a suitable partial protein source in rainbow trout larval feed.

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Aims: The aim of this study was to evaluate the hematological parameters in Cyprinus carpio juvenile feeding of Basilli sp. probiotics in the condition of before and after long distance transports.
Materials & Methods: In this experimental research, 180 carp juvenile were stocked in 2 tanks (capacity 400-L) for 45 days. Fish juvenile in one tank was feeding with multi-strain probiotic (Protexin) were used at a concentration of 1×10⁷ CFU/ liter and fish in the other tank was not consumed probiotic. At the end of the feeding trial, the carp juvenile from both treatments randomly were packed in plastic bags (40-L) at the density of 1kg/bag (~20 fish/bag). The juvenile feeding previously from probiotic were packed in 2 treatments with/or without of NaCl in water. Also, the juvenile feed of the control tank was packed in bags as the control. The bags unpacked after 12h and blood samples were taken from 10 fish in each replicate and hematological parameters were compared among the groups.
Findings: Results indicate that WBC, Hematocrit, Hemoglobin, MCV, MCH, MCHC and leukocytes differential count are affected by after transport stress and before the catching (p<0.05). However, there were no significant differences in the amounts of RBC and hemoglobin in experimental treatments (p>0.05).
Conclusion: Based on the results, finding of this study indicated that feeding of common carp juvenile with Basilli sp. probiotics had positive effects on blood parameters after long-distance transportation in plastic baggage, thereby if used in diet, it can be good alternatives to salt.

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Aims: The objective of this research was to investigate the effects of three commercial prebiotics A-Max, Celmanax and Ultra (each of 0.5, 1 and 1.5 g/kg diets) on growth, feed performance and blood biochemical compounds of beluga juvenile.
Materials & Methods: 900 fish with average weight of 21.5± 0.89 gr feeding was performed in 9 treatments (which on with three replicate) for 60 days. Control treatment was without supplementation. Fish were fed to satiation triple daily of 5% body weight. At the end of this period, the feed and growth performance were measured.
Findings: There was a significantly higher final body weight in ultra 0.5 (90.00± 21.78 g) compared with control (37.50± 9.60 g). The highest and lowest of food conversion were in treatments control and ultra (0.5), respectively. The results showed that the highest Fat and protein efficiency ratio was obtained in Ultra 0.5 (2.19± 0.77 and 7.37± 2.60) and lowest in control. Generally, the best treatments were in groups: Celmanax (dose of 0.5), A-Max (dose of 1.5) and Ultra (0.5). In addition, after determining the proper dose, blood samples were collected fish in the above-mentioned treatments. Based on the results of blood biochemistry parameters, there were no significant difference AST, ALP and ALT activity, so that the highest amount was obtained in the control. There were no significant differences in protein and cortisol experiment groups.
Conclusion: The results showed that the use of prebiotics in juvenile sturgeon diet has positive effects on feed performance and blood biochemical parameters.

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Because of the importance of osmoregulation in success of the juvenile Caspian Roach (Rutilus caspicus) release, maintenance and their restoration, this study was performed with the aim of the evaluation of these fish (average weight of 1.4 g± 0.018 g) to the salinity tolerance of the Caspian Sea by abrupt and gradual transfer methods on two different occasions of short-term (24 hours) and long-term (21 days). For this reason, 360 juvenile roaches were distributed to 9 different experimental treatments (each of them with 3 replicates) with 1) increased abrupt salinity (direct transfer to the Caspian Sea water), 2) increased gradual salinity (3 ppt for every 24 hrs) and 3) the Control group (freshwater). In order to evaluate the ion regulation, osmolality, Na⁺, K⁺ and Cl^- were measured in fish. Some immune responses related to the increased salinity (immunoglobulin and lysozyme) and stress indices (cortisol and glucose) were also measured. Based on the obtained results, the fish in both treatments of increased salinity showed high percentage of survival. All parameters related to ion regulation were decreased after a primary increase. Furthermore, the trend of cortisol and immunoglobulin changes were negatively correlated showing decreased stress response and increased immune system for both salinity transfer methods. Thus, the roach juveniles (1-2 g) are able to be transferred into the Caspian Sea directly.