فصلنامه تغذیه آبزیان
سال چهارم شماره 1 (پیاپی 7، بهار و تابستان 1397)

This study was conducted to evaluate the effects of different levels of Echinacea angustifolia and Origanum majorana extracts on growth performance, feed efficiency and survival of rainbow trout (Oncorhynchus mykiss) juveniles. Seven experimental diets with 0 (control), 0.1, 0.2 and 0.4% E. angustifolia and 0.1, 0.2 and 0.4% O. majoranawere prepared. Fish with initial weight 2.6 ± 0.3 g were randomly divided into 7 groups in triplicates and were fed with experimental diet for 4 weeks. At the end trial, the growth parameters, feed efficiency and survival were calculated. Growth and feed indices such as specific growth rate (SGR), Feed conversion ratio (FCR), weight gain, feed efficiency, average final weight, protein efficiency ratio were significantly affected by different levels of plant extracts (P<0.05). Experimental treatments were not significantly affect on condition factor and final length (P>0.05). However, condition factor was higher in fish fed higher levels of plant extracts. No mortality was observed during the experiment. Regression analyses showed relationship between SGR and FCR in fish fed O. majoranaextracts(P<0.05). According to the results of growth parameters and feed efficiency, it can be concluded that dietary 0.2% extract of E. purpurea and 0.1% of O. majorana have growth enhancement effects in this fish.

Artemia urmiana nauplii were used as a vector in bioencapsulation processing to carry blends of five probiotic bacilli called Protexin aquatic,including Bacillus circulans, B. subtilis, B. licheniformis, B. laterosporus and B. Polymyxa to digestive system of Beluga Huso huso larvae. Nauplii were bioencapsulated with three concentrations of 1×105 (T1), 2×105 (T2) and 3×105 (T3) bacteria per mililiter in suspension and were fed to Beluga larvae for 10 hours. The larvae were fed on the base of the 50% of their body weight for 6 times a day in a completely randomized design and the results were compared with control group (unbioencapsulated Artemia nauplii) in fourteenth day of experiment. The results suggest a positive effect of probiotic bacillus on growth of Beluga larvae compared to the control group. The highest weight was obtained in fish fed by bioencapsulated Artemia with a concentration of 1×105 bacteria/mL. . Food conversion rate significantly decreased in experimental treatments. The probiotic bacilli had significant positive effects on the specific growth rate, relative gain ratio, survival rate, average daily growth and thermal growth coefficient in comparison with control (P<0.05). However, condition factor did not show any significant difference (P>0.05). The results showed that probiotic bacilli have the highest ability in increasing the growth of Beluga larvae and fish fed by bioencapsulated Artemia with a concentration of 1×105 bacteria/mL had the best results.

The aim of this study was to investigate the effect of different dietary crude protein/energy ratios on growth indices and body composition of Bester juveniles. Triplicate groups (60 individuals per group) of fish (average weight ± SD, 358.4 ± 13.37g) were fed with three diet (D1, D2 and D3) including 31.67%, 35.54% and 40.86% of crude protein and 4377, 4800 and 5344 kcal of energy/kg, respectively, during eight weeks based on 1.5% of biomass per day. The result showed different significant of growth parameters (P<0.05). Body weight increase, condition factor, specific growth rate, average daily growth, protein productive value, and feed conversion ratio (FCR) improved in D2 and D3 treatment groups compared with D1. Comparison of the carcass composition of examined fish showed significant different between treatment groups (P<0.05). Therefore, the highest moisture, lipid and ash level of carcass gained in fish fed with diet D2 (P<0.05). Also highest carcass crude protein recorded in fish fed with diet D3 (P<0.05). These results suggested that the diet including 35.54% of crude protein and 4800 kcal of energy/kg is economic and suitable for culture of juvenile Bester.

This study was conducted to investigate the effects of dietary betaineon fecundity, fertilization, hatching, larvae survival rates and interval times among continuous spawning in the Golden Severum, Heros severus. For this purpose, three experimental diet treatments were applied to Severum brood stocks as follow: an ornamental commercial diet without betaine (control diet), the commercial diet with 5g betaine per kg food (treatment 2) and the commercial diet with 10g betaine per kg food (treatment 3). Four replicates were used in this trial. In this study, 12 pairs of spawning Severum fish has been kept in 12 aquariums with 50 liters volume, in 28 ± 1°C. Feeding were two times a day. The highest fecundity with average of 655.4 eggs were observed in treatment 3 and the highest hatching rate and larval survival rate respectively 98.79 and 94.58 were observed in treatment 2 which were significantly different from the control (P≤0.05). The shortest interval times between continuous spawning with average of 7.31 days was observed in treatment fed with 5g betaine per kilogram diet which was significantly different from the other treatments. In summary, it can be concluded that using betaine with 5 g per kg diet can make a positive increasing in reproductive performance in Severum fish.

The purpose of this study was to investigate the effect of dietary pistachio hull extract (PHE) on physiological responses of common carp Cyprinus carpio following handling stress. Fish were fed five experimental diets supplemented with 0, 0.5, 1.5, 4.5, 9 g PHE/kg diet. At the end of the experiment, all fish (n=12) in each tank were subjected to acute handling and air exposure stresses. Obtained results showed that fish fed PHE at 0, 0.5, 1.5 g/kg diet had significant increase (P<0.05) in glucose in comparison with initial time (before subjected to stress). These results indicate that different levels of dietary PHE failed to reduce cortisol levels of serum after stress. According to results, it can be concluded that 1.5 g PHE/kg diet added to the diet has a good effect on response to stress in common carp.

This study aimed to investigate the histoarchitecture of the esophagus in common bream (Abramis brama) during early development using light microscopy and transmission electron microscope (TEM) from hatching up to day 60 post hatch (DPH). Larvae were sampled randomly every day from hatching time to 6 DPH, on every alternate day from 8 DPH to 20 DPH, every 5 days from 25 DPH to 40 DPH, and two last samples have down at 50 and 60 DPH. Then fish larvae were fixed by immersion in Bouin´s solution and 4% glutaraldehide (pH = 7.4). Results showed that the esophagus differentiated from the anterior part of the alimentary tract at hatching time. At 1 DPH, the esophagus lined by squamous cells and forming a tine tubular structure lined with cubical cells. First goblet cell was observed at 2 DPH in the mucosal layer of the esophagus. At 3 DPH, they showed presence of the various mucosal material. In addition, epithelium of the esophagus changed to columnar cells. The first taste bud was detected at 5 DPH and the main phenomenon was the appearance of a serrated outline of the esophagus apical cells. Longitudinal folds of the esophagus were developed at 8 DPH. No remarkable histological changes were observed till 25 DPH, but the number of the taste buds and goblet cells and their size were increased. From 25 to 60 DPH, low dense of goblet cell, increasing in posterior esophagus region, led to differed histological characteristics with anterior esophagus segment encompassed increasing number of taste buds.

Various researches have proved that growth and biochemical content of rotifers can be affected by type and concentration of food. Microalgae as a source of food are essential for the rotifer rearing, especially for its growth, survival, protein, lipid and fatty acids contents. The present study was carried out to compare the effects of dried algae (powdered chlorella) (equivalent weight of fresh algae) on growth factor, and proximate body composition of rotifer Brachionus plicatilis in comparison with fresh algae (Isochrysis galbana and Nannochloropsis oculata) at 5×106 cells/mL. Rotifers were cultured in standard conditions in 500 mL plastic containers with initial density of 30 ind/mL. The results showed that the population growth rate of rotifers fed with I. galbana (5×106 cells/mL) was higher than the treatments fed with the chlorella powder and N. oculata (P<0.05). High specific growth rate was in treatment fed with I. galbana (P<0.05), while the lowest was in rotifers fed with powdered chlorella. The protein and lipid contents were significantly higher in rotifers fed with chlorella powder and I. galbana, respectively. The highest DHA and DHA/EPA were significantly found in treatments fed with I. galbana, while the high amount of EPA was significantly showed in treatment fed with N. oculata. The present study showed that fresh algae can be better to create growth in marine rotifer than chlorella powder.

This study aimed to introduce new protein sources to replace fish powder in diets for rainbow trout, Oncorhynchus mykiss. In this study, fish powder protein was replaced with the typical Kabuli chickpea (Cicer arietinum) and irradiated pea seeds in the diet followed by assessing their effects on growth and nutritional indices, digestion and body composition of rainbow trout. The study was conducted in the Artemia and Aquatics Propagation Research Institute, University of Urmia, Urmia, Iran. 720 juvenile O. mykiss (60 ± 4 g) were randomly divided equally into eight treatments with three replicates, and were fed with experimental diets for 60 days. The experimental diets were commercial food, homemade food without pea (control), typical pea diets containing 20, 30 and 40% and diets containing 20, 30 and 40% irradiated pea. The results showed that radiation has not significantly affected the food ingredients of peas (protein, fat and dry matter) and growth parameters (P>0.05), but there were significant changes in nutritional indicators and digestibility of the diet along with increasing the percent of peas replacement (P<0.05). As a result, the increase in radiation as well as 40% peas in the diet of O. mykiss did not exhibit negative impact on growth performance. Therefore, the irradiated pea protein can be a good food item to replace fish powder in the fish diet.