فصلنامه تغذیه آبزیان
سال ششم شماره 3 (پیاپی 13، پاییز 1399)

The aim of this study was to compare the effects of adding taurine to diet as a mixture with feed and also as spray on growth and feeding performance, body composition and physiological responses of Asian sea bass, Lates calcarifer (13.62 ± 0.2 g). This study was carried out in a completely randomized design as three treatments with triplicates. Fish were fed with feed containing 0 (control group), 10 g/kg taurine in feed as mixture (treatment M) and 10 g/kg as spray on feed (treatment S) for 6 weeks. At the end of the experiment, final weight, weight gain, specific growth rate and feed conversion ratio were significantly higher in treatment S compared to the control and treatment M (p < 0.05). Carcass fat and moisture contents significantly varied in treatment M with the control and with treatment S (p < 0.05). However, carcass protein value was not influenced by supplemented tuarine (p>0.05). The obtained results indicated that dietary taurine did not enhance Asian sea bass blood biochemical factors and non-specific immune response (p>0.05). Overall, it can be concluded that feeding Asian sea bass with the diet supplemented by 10 g taurine as spray for a period of 6 weeks enhances the growth and feeding performance.

Exogenous multi-enzyme supplementations can eliminate the effects of antinutritional factors and improve the growth performance of aquatic animals. The purpose of this study was to investigate utilizing Kemin multi-enzyme supplementation in the diet and its effects on growth factors, body composition, and some blood biochemical parameters in Carassius auratus gibelio. The experiment was conducted in a completely randomized experimental design with 5 treatments and 3 replications. The Kemin at 4 levels of 0, 250, 500, 750, and 1000 mg/kg was added to the diet and given the experimental diets to fishes for 8 weeks and growth factors, Weight growth percent (WGP), specific growth rate (SGR), feed conversion ratio (FCR), Condition factor (CF), Protein efficiency ratio (PER) were studied. Body composition and blood biochemical factors (glucose, total protein, albumin, cholesterol, and triglyceride) were measured and evaluated. Different treatments of CF were not significantly different from each other (P> 0.05). But WGP, SGR, FCR and PER, the enzyme levels of 500, 750, and 1000 mg/kg were significantly different from the control group (P <0.05). Body composition and blood biochemical parameters were not significantly different between enzyme levels (P> 0.05). Based on the results of this study, it seems that Kemin multi-enzyme supplementation diets can improve the growth and FCR in Carassius auratus gibelio.

Study of fishes’ alimentary canal ontogeny is important to understand their nutritional requirements during their early development and is a research priority for candidate species in aquaculture. Therefore, this work was conducted to study the early development of the Binni fish’s (Mesopotamichthys sharpeyi) alimentary canalusing histological method. A total of 200 larvae and fry were sampled from hatching up to 41 day post hatching (DPH), and then histological sections were prepared using paraffin method and staining with hematoxylin-eosin. Based on the results, mouth opening, exogenous feeding and the esophagus development covered with a cuboid epithelium were happened on 3 DPH, and the emergence of the gill arches on the 4 DPH. The complete absorption of the yolk sacs was lasted until the 4 DPH. The developmental characteristics of Binni fish during its early stages indicated the concurrence of biological structures with their needs. In addition, these ontogenic changes were similar to those of other cyprinid’s digestive system.

To evaluate the flesh quality of fingerling common carp reared in aquaponics culture system, fish with cucumber and lettuce was reared under the aquaponics system for 60 days with three treatments including cultivation of common carp without plants (T0), an aquaponics system for culturing common carp with lettuce (TL), and cucumber (TC) each with three replications. For the meat quality evaluation of reared fish, at the final rearing period after harvesting fish, chemical composition, fatty acid profile, color, texture profile analysis, and sensory assessment were determined. The result showed that protein and lipid content in T0 and TC were significantly higher than in TL (P<0.05). Most of the sum monounsaturated fatty acids (∑MUFA) and polyunsaturated fatty acids (∑PUFA) were recorded in TC and T0, respectively. Lipid quality base on the atherogenic (AI) and thrombogenic (TI) indices in TL was higher than in TC. According to color indices, fish skin in T0 and TL exhibited similar lightness and transparency, higher than in Tc. The color of fish muscle in TC displayed redness higher than in the other treatments. In case of texture profile analysis, springiness in TC was significantly higher compare to the other treatments. In case of sensory assessment, the score of odor attribute in TC was significantly lower compare to the other treatments. In conclusion, the muscle quality in the fish reared under aquaponics culture system was more acceptable in comparison with that in T0 (common carp reared without the plants) and in case of fish reared under aquaponics system, those reared with cucumber revealed better quality than the lettuce.

This study was conducted to evaluate the effects of different dietary levels of butyric acid on growth performance, immunity and digestive enzyme activities in yellowfin seabream (Acanthopagrus latus) (8.59 ± 0.33 g) at the period of 60 days. After 2-week adaptation, 120 fish with a density of 10 fish/tank in a completely randomized design were distributed to 12 tanks. Fish were fed with 4 levels of butyric acid including zero (control), 2.5 (T1), 5 (T2) and 10 g/kg (T3) of diet 2 times per day. The results showed that different levels of butyric acid in diet had significant effects on growth performance and nutritional indices compared to the control (p<0.05). However, protein productive value of T1 and control exhibited no significant difference (p>0.05). The food conversion ratio in control group was significantly higher than in the other treatments (p<0.05). Nonspecific immune responses, lysozyme activity and ACH50 in T3 were also significantly higher than in the other treatments (p<0.05). Protease activity in T3 and also amylase in T2 and T3 were significantly increased compared to the control (p<0.05), whereas lipase activity did not exhibit any significant difference (p>0.05). In conclusion, butyric acid, especially at the level of 10 g/kg of diet, displayed positive effects on the growth, immune indices and enzyme activities in yellowfin seabream.

The aim of this study was to investigate the antimicrobial effects of kefir as a dietary supplement on the growth and infection caused by Aeromonas hydrophila in Cyprinus carpio. Totally, 72 juvenile carp weighing approximately 10-15 g were used. The fish were divided into 4 groups fed with 3, 5 and 10% kefir and the control group (without adding kefir) with three replications (six fish per replication) and were fed 3% of their body weight daily. The antimicrobial effect of kefir against A. hydrophila was investigated as well. After two weeks, the levels of IgM, ALT, AST, ALP and total protein in fish serum were evaluated. The liver, kidney and spleen tissues of fish were examined for histological study. The results showed that the 48-h kefir product had the highest antimicrobial effect against A. hydrophila. Feeding the fish with 3% kefir caused significant increases in length and weight of the fish. The statistical analyses revealed that the levels of IgM, AST, ALP and the serum total protein were not significantly different between the four groups, while the average amount of ALT in treatment 3% exhibited significant difference, which was less than the other two groups, while was not significantly different from the control. All experimental groups exposed to A. hydrophila revealed tissue damage in liver, kidney and spleen. However, tissue damage was less in treatment 3%.