فصلنامه تغذیه آبزیان
سال نهم شماره 1 (پیاپی 23، بهار 1402)

The aim of the present study was to evaluate effects of different levels of thyme, Zataria multiflora (n growth performance, body chemical composition and resistance to environmental stressors such as temperature and acidity in zebra fish, Danio rerio. 480 Fish with an average weight of 0.33 ± 0.08 g were distributed in 12 tanks and fed by four isonitrogenous and isoenergetic diets including replacement levels of 0, 1, 1.5 and 2% thyme powder (T0, T1%, T1.5% and T2% respectively). After 10 weeks, growth performance, survival and body proximate composition, were determined, then 10 fish per tank were taken for environmental resistance and 10 fish per tank for the body composition analysis. According to the results, the highest final weight, weight gain, body weight increase, specific growth rate and protein efficiency ratio were obtained in T2% (p < 0.05), while the lowest feed conversion ratio in T2%. It was also true for the highest survival rates which were also found in T2% but not significant (p>0.05). Differences among treatments in survival rate against acidity and temperatures were also not significant (p>0.05). Significant difference between treatments were observed in body composition including moisture, protein, fat and ash (p<0.05). In conclusion, using thyme powder at the food dietary of the zebra fish, can affect the growth performance, carcass composition and survival rate of D. rerio but not on resistance against the environmental stressors.

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.

Nowadays, given the numerous disease problems that have arisen in shrimp farms, the utilization of nutritional supplements to strengthen the immune response and controlling the common diseases in dense shrimp farming have been highly regarded.  So, the present study aimed to investigate the effect of basic diet formulated with different levels of Moringa oleifera leaf powder (25, 50 and 100g/kg) and ethanolic extract (0.25, 0.5 and 1g/kg) in seven treatments each with three replicates on the expression of immune genes in the Pacific white shrimp Litopenaeus vannamei. After 8 weeks, the mRNA expression of four immune genes, including alpha-2-macroglobulin (α2M), Lipopolysaccharide and B1,3-glucan binding protein (LGBP), Peroxinectin (PX) and integrinß, were measured in the hepatopancreas using Real-time PCR technique. The results showed a statistically significant differences in the expression levels of the α2M, LGBP, PX genes in all treatments (p<0.05). The expression level of α2M in treatments of 0.25 and 0.5 g/kg extracts and 25 g/kg Moringa leaf powder were significantly higher than that of the other treatments (p<0.05). The highest levels of LGBP expression were observed in 0.5 and 1g/kg Moringa leaf extract and the highest level of PX gene expression was observed in 0.5 and 1g/kg Moringa leaf extract and 25g/kg Moringa leaf powder treatments, which was significantly higher than other treatments and the control treatment (p<0.05). In conclusion, the results of this study showed the positive effects of using 0.5 and 1 g/kg Moringa leaf extract and 25 g/kg leaf powder on the functioning of the immune system in L. vannamei.

Extrusion process is widely used in food processing. This process is effective on the anti-nutritional factors present in food raw materials and their digestibility. In treatments 1, 2 and 3 acorn flour with particles less than 250 microns in diameter was mixed with tap water at the rate of 200, 100 and 200 mL per kg of flour and then extruded by a single-axis extruder under the temperature of 135, 135 and 100 °C, respectively. Treatment 4 (control) was not subjected to the conditions of dough preparation and then extruded. Extruding exhibited no significant effect on ash content and non-tannin phenolic compounds of oak flour (p>0.05). However, it significantly decreased the contents of crude protein, crude fat, total phenolic compounds and condense tannins, while led to the elevation in  the digestibility of carbohydrate and protein (p<0.05). In extruded treatments, there were no significant differences in crude protein, crude fat, ash, total phenolic compounds, non-tannin phenolic compounds and condensed tannins. The highest carbohydrate digestibility was observed in treatments 1 and 2, and the highest protein digestibility in treatment 2 (p<0.05). In total, treatment 2 (135 °C and 100 mL tap water per kg flour) was recognized as the best treatment for extruding oak acorn flour for common carp.

This study was conducted to investigate the effect of replacing fish oil with canola oil in the diet on the growth performance and biochemical composition of common carp fingerlings. To carry out this study, a total number of 180 common carp fingerlings were introduced in twelve 100-L fiberglass tanks with an average weight of 4.07 ± 0.7 g and an average total length of 7 ± 3 cm. Four diets with the same protein, fat and energy levels were formulated. Canola oil was replaced with fish oil at four levels of 0, 25, 50 and 75%. Fingerlings were fed three times a day for 8 weeks based on 3% of body weight. At the end of the experiment, growth indices, and carcass biochemical composition was measured. Based on the obtained results, no significant differences were observed among the treatments in terms of food conversion ratio, protein efficiency ratio, specific growth rate, body weight gain, total length increase, average daily growth, condition factor, survival rate, final length, and final weight (p>0.05). The results of carcass composition also showed that there was no significant difference in the carcass moisture content between the treatments (p>0.05). However, significant differences were recorded in the contents of protein, ash and fat (p<0.05). According to the findings, different levels of canola oil in the diet did not affect the growth performance and carcass composition in the common carp fingerlings.

In this study, using different biological factors, we tried to remove the fish metabolites and improve the water quality in the culture system. Therefore, operation of some recirculating system were investigated during a 2-month culture period. The biological factors were bacterial (aerobic and none aerobic bacteria, in two separate departments), Lemnea plant and hetrotrophic bacteria for formation of biofloc with adjusting the ratio of C/N. The treatments included 1- a system consisted of the plant (P), 2- a system comprised the plant and biofilter (PB), a system containing of the plant, biofilter and biofloc (FBP) and finally, a system without biological compartment just physical section as control. Twenty tilapia fingerlings (10 ± 0.5 g) were introduced in each experimental unit. The results indicated that efficiency of FBP system based on food conversion ratio, specific growth rate and survival was significantly higher than other culture systems (p<0.05). The fish were died at the 23th day of initiation of the study in the control system. The rate of Lemnea plant in the treatment P was significantly higher than in other treatments (p<0.05). The concentrations of Ca, P, nitrate, ammonia, nitrite and pH were significantly different among treatments. So that, these minerals in treatment FBP were lower than those in the other treatments at the end of the study. The results indicated that using different biological methods (together) in a tilapia culture system could be more efficient in the removal of fish metabolites, in addition to the improvement of fish growth and plant in an integrated fish and plant culture system.