فصلنامه تغذیه آبزیان
سال هفتم شماره 2 (پیاپی 16، تابستان 1400)

In this study the mutual effects of zinc nanoparticles (Zn NPs) and vitamin E nanoparticles (Vit E NPs) on growth and immune parameters of fingerling sized Cyprinus Carpio with an average weight of 9 g was evaluated over a period of 60 days in three different treatment (Treatment I : 100 IU/kg normal vitamin E plus 15 mg/kg normal zinc sulfate; treatment II: 100 IU/kg Vit E NPs plus 15 kg/mg Zn NPs; treatment III: 300 IU/kg Vit E NPs plus 15 kg/mg Zn NPs) groups compared to the control group that received normal diet without any supplements. The results showed significant increase in % weight gain (%WG, 144.1 ± 56.85), Average daily growth (ADG, 41.15 ± 2), specific growth rate (SGR, 46.13 ± 1) and feed conversion ratio (FCR, 59.68 ± 4), immunoglobulin(IgM , 4.49± 1.71) in treatment group III compared to the control group (p < 0.05). However, the condition factor (CF) was the highest in the control group and there was no significant difference between the control group and the treatment groups (p > 0.05). Based on these findings, treatment III is recommended for increasing the growth parameters and treatment II for increasing immune parameter in this species of fish.

This study was performed to evaluate the ability of juvenile Caspian roach Rutilus caspicus (1.4 ± 0.018 g) to acclimate to the salinity of the Caspian Sea by the direct transfer method with short-term starvation and re-feeding periods within 60 days. So, 450 juvenile fish were randomly distributed into 5 groups: three groups were deprived from feeding for 3, 5 and 7 days (3S, 5S and 7S). They were then re-fed for 10 days and this cycle was repeated during 46 days. Forth group were unfed during the whole experimental period (S) and fifth group were continuously fed (F or control group). All fish after the starvation-refeeding in freshwater were directly transferred to the Caspian Sea water for 14 days, and staved during this period. Growth performance were evaluated for all of the experimental treatments. Some of stress indices (osmolality, cortisol and glucose) and immune response (total immunoglobulin and lysozyme) concerning to the alternative nutritional periods and abrupt salinity elevation were measured in fish blood. The highest and lowest fish growth performance were obtained in F and S groups, respectively. Osmolality and lysozyme activity were not statistically significant between F, 3S and 5S groups. Total immunoglobulin was significantly increased in 5S (31.50 ± 0.99 mg/g). The highest cortisol and glucose concentrations were obtained in groups 7S and S compared to the other experimental groups. The results showed that, not only the juvenile roach with the short-term feed deprivation periods in 3S and 5S groups were not affected by physiological stress due to starvation and increased salinity, but also their growth performance enhanced because of living in iso-osmotic environment of the Caspian Sea.

The aim of the present study is to investigate the effect of microalgae (Chlorella vulgaris) and brewer’s yeast (Saccharomyces cerevisiae) on growth performance, digestive enzymes activity and intestinal microbiota in sterlet juveniles (Acipenser ruthenus). Total number of 315 sterlet juveniles (24.5 ± 0.2g) were divided into 7 treatments and were fed with a basal diet containing different amounts of Chlorella and yeast during 8 weeks. Treatments 1 to 7 were fed with a basal diet supplemented with no chlorella and yeast (control), 1% yeast, 0.5% yeast, 3% Chlorella, 5% Chlorella, a combination of 0.5% yeast and 5% Chlorella and a combination of 0.5% yeast and 5% Chlorella, respectively. At the end of trial, growth factors, digestive enzymes and total number of intestinal bacteria were measured. The results showed that the addition of yeast and Chlorella to the fish diet improved growth performance, increased the secretion of digestive enzymes and also increased the number of intestinal bacteria compared to the control (p<0.05). The best growth performance was observed in treatments 5 (5% Chlorella) and then treatments 6 and 7 (combination of Chlorella and yeast) so that the highest amount of body weight gain, average daily growth, specific growth rate, and the lowest feed conversion ratio were observed in treatments 5, 6 and 7 (p<0.05). No significant difference was seen in the survival rate between treatments (p>0.05). The results showed that supplementing the diet of sterlet juveniles with microalgae and brewer’s yeast as well as their combination significantly improve the growth performance, secretion of digestive enzymes and intestinal bacterial flora.

The study was executed to find out the potential effects Sanyar prebiotic on production performance, water nitrogen compounds, blood and metabolic parameters of Common carp (Cyprinus carpio) reared in a biofloc system. 324 fish fingerlings (average weight 10.09 ± 0.45 g) were stocked in eighteen 35-L tanks (18 fish in each tank). Six experimental groups after 10 days of adaptation to laboratory conditions were tested for 60 days, which including: Control group without additive with clean water (C), Control group without additive with Floc (FC), Floc groups with 0.1 and 0.2 g (FP1 and FP2) powder prebiotic and Floc groups with 1 and 2 ml (FL1 and FL2) liquid prebiotic per 100 g of basic diet. At the end of the experiment, the FP1 group significantly increased final biomass weight, final density, and protein efficiency ratio (PER) and decreased feed conversion ratio (FCR) when compared to other groups. Total water ammonia was reduced in the biofloc groups containing prebiotic supplementation compared to the biofloc group without prebiotic (FC). Serum urea and creatinine levels increased significantly in the FC group compared to the other experimental groups. ALT, AST and ALP enzymes were significantly increased in groups C and FC compared to the groups fed with Saynar prebiotic. The highest WBC and RBC counts were obtained in FL1 and FC groups, respectively. In conclusion, dietary supplementation of FP1 (0.1 g Sanyar prebiotic per 100 g of basic diet) can be potentially used as health enhancer in Common carp cultured under biofloc system.

In this study with using plant proteins and yeast, several balanced protein diets were made with the aim of reducing the consumption of fish meal. Rainbow trout fingerlings (Oncorhynchus mykiss) to experimental diets and cultured in the aquaponics systems. The experimental treatments were control treatment (commercial diet), treatment 1(25% Fish meal (M)  and 57% (Plant protein) pp, treatment  (23%FM,4%yeast,47%pp) treatment3 (20%FM,9%yeast,52%pp) ,treatment4 (18/5%FM,14/5%yeast,46%pp),treatment5 (17%FM,21%yeast,41%pp), treatment6(10%FM,25%yeast,45%pp),treatment7(28/5%yeast,45%pp).The160 rainbow trout fingerlings with an average weight of 38 ± 2 and the 320 seedlings of peppermint (Mentha piperita) with an average weight of 25±2 gr were randomly introduced to the 16 experimental units and cultured for nine weeks. The results showed that the growth performance of fish such as final weight, specific growth and protein efficiency rates increased in treatment 3 compared to other treatments (P<0/05). Carcass composition showed that the highest amount of crude protein was observed in treatment 3, the highest fat crude was observed in control treatment, the highest moisture content was obtained in treatments 6 and 7. And there was no significant difference in ash content between treatments(P>0/05). The data from total bacterial count showed that the highest total count of bacteria in the intestine, reservoir water, and plant roots belonged to treatment 5, and the other treatments did not have any significantly differences. It seems that in these treatments, there were an equilibrium among bacteria of fish intestines, reservoir water, and plant roots. The best experimental diet in combination with rainbow trout and peppermint was recorded in treatment 3, and it was demonstrated that to grow rainbow trout using diets containing vegetable proteins, yeast, without using fish meal, is possible but to get the best growth conditions, it is needed to have at least 10% fish meal in the diet.

Tilapia is an omnivorous fish that uses different levels of food. This species is more of a filter feeder that provides its own food by refining the food in the environment. The aim of this study was to evaluate the histomorphology of esophagus and intestine under the influence of replacing blood powder with fish powder in the diet of Nile tilapia. After preparation, fish were fed with designed diets containing 0, 25, 50, 75, and 100% blood powder for 8 weeks and each treatment was performed with three replications. After this period, the fish were anesthetized and after opening the abdominal area 0.5 cm tissue samples were taken from the esophagus and intestine, fixed in 10% formalin buffer, and after tissue preparation steps included dehydration with alcohol, clarification with xylol, blocking with paraffin, cutting 4-6 microns thick with microtome were done. Hematoxylin-eosin staining were performed and the study of microscopic slides were performed under a light microscope. The results of measuring and measuring indices such as height and thickness of villi, the thickness of epithelium and muscle layer, and change in the number of mucous cells in the esophagus and intestine in the group receiving blood powder completely and 75% compared to the control group and other groups has been less. Therefore, blood powder in the diet is somewhat tolerable and replaceable for the species.