فصلنامه تغذیه آبزیان
سال ششم شماره 4 (پیاپی 14، زمستان 1399)

The present study examined the effects of different protein concentrations  on growth of juvenile common carp kept in 15 fiberglass ponds (0.5 × 2 × 2 m) under intensive culture system involving 5 treatments and 3 replications, based on the following raw protein contents  (24.22, 26.15, 28.32, 30.31, 33.29%) included in the fish diet for a period of 60 days and with a water temperature ranging 22-31oC, and dissolve oxygen level of 5.1-7.3 mg/L to determine diet formulation ensuring an optimum growth performance. Each rearing pond was introduced with 250 pieces of juvenile fish (4 ± 0.66 g) amounting to an average of 1 kg fish biomass. The results indicated that juveniles receiving protein levels of 28.32% and 26.15% had the highest body weight, specific growth rate, weight gain percentage and protein yields (p≤0.05). In addition, the feed conversion ratio related to these two diets showed significant decline (p≤0.05). The condition factor and survival rate remained the same across all treatments (p≥0.05). The study revealed that the protein increment ratio of up to 28.15% in the diet contributed to the increased growth indices among juvenile common carp and concentrations beyond that did not lead to any effective increase in fish growth.

The aim of this study is to evaluate the Effect of different levels of turmeric on diet on Blood indicators and histopathological examination of liver, kidney and intestine in Juvenile Sevryuga. In this regard, 120 specimens were distributed in 12 Treatments (45 ± 0.5g) and (26 ± 0.5cm). The fish were fed in 4 groups with 4 experimental diets containing different levels of turmeric including: 0, 0.5, 1 and 2% formulated. At the end of the course , blood indices and histopathological examination of liver, kidney and intestine were evaluated. Increasing the dose of turmeric in 2% of the diet increased the amount of hematocrit, hemoglobin, RBC, AST and ALT and the difference between treatments was significant (P 0.05). The results of MCV ٬ MCH and MCHC analysis showed that the amount of the mentioned indicators decreased with increasing the dose of turmeric and the difference between the treatments was significant (P

This study aimed to evaluate the fillet quality of rainbow trout, Oncorhynchus mykiss after feeding with different levels of Celmanax prebiotic. A total of 780 trout with an initial body weight of 18 ± 2 g were randomly distributed after adaptation to the experiment environment in tanks filled with 105 L spring water (65 fish per tank). Three experimental groups and control each with three replicates were considered. Trout were fed with diets containing 2 (T2), 4 (T4) and 6 (T6) g/kg prebiotic for eight weeks. Then, the fish were filleted and maintained in the refrigerator. The chemical parameters including TVB-N, PV, TBA, FFA, TVC and PTC were estimated in 0, 3, 6, 9, and 12 days of storage time. No significant differences were observed in experimental groups and control in free fatty acids content in fillet (p>0.05). The amounts of peroxide and thiobarbituric acid in experimental groups were lower than control. The amount of TVB-N increased in experimental groups compared to control. The total viable count and psychrophilic count of bacteria in the control group were higher than the experimental groups (p<0.05). The lowest counts of bacteria belonged to T6 (p<0.05). This study showed that the increased levels of Celmanax prebiotic in trout diet could increase shelf-life of fillet in the refrigerator.

This study was carried out regarding the effects of cyclopoid copepod Acanthocyclops trajani on first feeding of beluga larvae (Huso huso). The treatments comprised a control diet containing Artemia naupli and Daphnia magna and a combined diet containing Artemia naupli, Daphnia magna and A. trajani. The results of this study indicated that the average length, body weight and specific growth rate in larvae of control and combined diets were not significantly different. In spite of the fact that, A. trajani was significantly different in the amount of n-3 fatty acids in comparison with the other live feeds in this study, but indicated more effectiveness in survival rates (80%) of beluga larvae, as a supplement. Furthermore, the combined diet was significantly different in DHA, in comparison with control diet. This study indicated that freshwater copepod is potential supplemental live food, to increase nutritional value from the point of view in terms of essential fatty acids and survival rate of valuable fish larvae such as beluga.

The aim of the present study was to investigate the effects of dietary lysophospholipid and carbohydrates (rye and corn meal) on growth performance, blood and biochemical parameters in rainbow trout. So, 480 fish (6.70 ± 0.99 g in weight) were fed with experimental diets containing 100 g/kg corn, 250 g/kg corn, 100 g/kg corn + 9 g/kg lysophospholipid, 250 g/kg corn + 9 g/kg lysophospholipid, 100 g/kg rye, 250 g/kg rye, 100 g/kg rye + 9 g/kg lysophospholipid and 250 g/kg rye + 9 g/kg lysophospholipid in triplicate. The experimental design was a 2 × 2 × 2 factorial arrangement. Results of growth performance demonstrated elevating in final weight, specific growth rate and feed intake in Tcorn100+lyso and Tray100+lyso, whereas Tcorn250+lyso and Tray250+lyso contrarily led to lower growth performance (p<0.05). Also, RBC and hematocrit indicated interaction effects between diet × lysophospholipid and lysophospholipid × carbohydrate level (p<0.05). RBC and hematocrit were elevated in Tcorn100+lyso and Tray100+lyso (p<0.05). Comparative results of biochemical parameters showed reaction effects of cholesterol between diet × lysophospholipid (p<0.05). Cholesterol values reduced by adding lysophospholipid to different levels of rye and corn and also higher value was observed in Tcorn100+lyso and Tray100+lyso compared to Tcorn250+lyso and Tray250+lyso (p<0.05). It seems that rainbow trout has potency of using 250 g rye and corn in diet containing fat powder without lysophospholipid, while lysophospholipid negatively affects this level of carbohydrates. However, lysophospholipid helps enhancing growth and erythropoiesis in the levels of 100 g rye and corn.

The Bio-Floc has more efficacies compared to fixed Bio-film for removing the nitrogen compounds in water recirculating fish culture system. In this trial, a completely randomized experimental design was run to evaluate the roles of three different ratios of carbon to nitrogen (C:N) including 10 (treatment 10 = T10), 15 (T15) and 20 (T20), into the carp culture systems on growth and water quality. The mean individual weight was significantly higher in T20 compared to the other treatments. At the end of the experiment, the fish attained from 70 to 552.8, 704.7 and 708.8 g in T10, T15 and T20, respectively. The FCR, ammonia and nitrate concentrations were significantly higher in T10 compared to the other treatments (p<0.05). Concentration of ammonia in T10, T15 and T20 were 78, 29.9 and 29.9 mg/L, respectively. A depletion trend was recorded in pH in all treatments during the experimental period. The electrical conductivity (EC) and Bio-Floc formation rate increased in all treatments and was significantly higher in T20. The EC of water were 1327.5, 1419.83 and 1419.83 mmos/cm in T10, T15 and T20, respectively. The rates of Bio-Floc reached to 71, 143, 163 mL/L in T10, T15 and T20, respectively. The results of this experiment indicated that using molasses to adjust C:N ratio of water at 20, enhances formation of Bio-Floc, carp growth rate and water quality in a zero-exchange water system.