نشریه توسعه آبزی پروری
سال هجدهم شماره 3 (پاییز 1403)

The aim of the research was to determine the effect of feeding frequency on growth indicators, carcass composition, activity of some digestive enzymes and survival of beluga (Huso huso) larvae. For this purpose, the total number of 10800 beluga larvae, with initial weight of 0.048+0.001 g, were randomly stocked in 36 500-liter fiberglass tanks containing 100 liters of well water, for 31 days with a feeding frequency of 6 and 12 times a day using Artemia nauplii, Artemia biomass, Daphnia, chironomid larvae and formulated diet were reared. The results showed that, feeding larvae with chironomid larvae or Artemia biomass, could increase the survival rate and weight of larvae, respectively. The survival percentage of the treatments on different days after hatching of the larvae during 12 times of feeding per day in most treatments was significantly higher than that of 6 times of feeding per day (p<0.05). The average weight of larvae in different treatments, when feeding 12 times a day compared to feeding 6 times a day, had no statistically significant difference (p>0.05). In most treatments, carcass protein content of larvae, during 12 and 6 times feeding a day, had no statistically significant difference (p>0.05). But the carcass fat content, during 12 times feeding per day in half of treatments, was significantly higher than 6 times feeding per day (p<0.05). The activity of pepsin, trypsin and lipase enzymes, during 12 times feeding a day was significantly more than 6 times a day feeding. Totally, feeding larvae 12 times a day was preferable to feeding 6 times a day, based on improvement of survival of larvae, condition factore and activity of enzymes.

In order to achieve a better and more economical diet for the cultivation of Artemia, three diets were used: chickpea flour (100%) as the first nutritional treatment, soybean flour (100%) as the second nutritional treatment, and a third nutritional treatment consisting of chickpea flour (40%), soybean meal (40%), and sesame flour (20%) compared to the control group fed with Spirulina algae. Feeding with experimental diets was carried out in three replicates, and the experiment lasted from hatching to the maturity of the last treatment group, which was 23 days. The results showed a significant difference in average length growth between the groups fed with different treatments and the control group (p>0.05). The average total length of Artemia in the second treatment group (soybean flour) was the highest (1.98 ± 0.01 cm), while the control group (Spirulina) had the lowest value (0.60 ± 0.01 cm). The maturation of Artemia in the individuals of the group (with a minimum of ten mature individuals in each of the three replicates) as an effective phenomenon in the growth interruption occurred in the first nutritional treatment (chickpea flour) on the 18th day of feeding, followed by maturation in the second nutritional treatment group (soybean flour) after twenty days and in the third nutritional treatment group (mixed flour) after twenty-three days. Until the end of the maturation day of the treatment groups, the control group of Artemia fed with Spirulina algae did not reach maturity. Feeding the larvae after nauplii hatching with chickpea flour as the first option and also with soybean meal in this experiment resulted in better length growth compared to Spirulina algae.

This study was conducted to evaluate the effects of different levels of biosilage produced from the wastes of warmwater fish in the practical diet on growth performance, survival, and carcass composition of common carp (Cyprinus carpio). Juveniles (average initial weight of 48±1.3 g) were fed in 15 fiberglass tanks with a useful capacity of 200 liters (with a stocking density of 20 fish per tank) and in five treatments including control diet (carp pellets with fishmeal and no biosilage), 25% (25% biosilage + 75% fishmeal), 50% (50% biosilage + 50% fishmeal), 75% (75% biosilage + 25% fishmeal) and diet containing 100% biosilage for 56 days. No significant difference was observed in the survival rate of fish between treatments (p≥0.05). Final body weight gain, specific growth rate, protein efficiency ratio and food conversion ratio in the diet of 50% (50% biosilage + 50% fishmeal) showed the best performance (p≤0.05); and inclusion levels higher than 50% and finally levels lower than showed performances. Crude protein content of carcass in fish fed 50% biosilage + 50% fishmeal and then 75% biosilage + 25% fishmeal showed significant differences compared to other groups (p≤0.05). The lowest amount of crude carcass lipid was obtained in fish fed with 50% biosilage + 50% fishmeal, which had a significant difference with other groups (p≤0.05). Based on the results, it is suggested that the possibility of substituting 50% biosilage obtained from warmwater fish waste instead of fishmeal in the diet of common carp led to increased growth, improved food conversion ratio and carcass quality.

Untreated effluent in most trout culture farms in Mazandaran province is discharged into the environment. Characteristics of effluents from seven flow-through trout farms in the plain of Amol city are investigated. Water samples were taken from both inlet and outlet of fish farms. Thirteen physical and chemical parameters of effluent that were analyzed indicated that the concentrations of Dissolved Oxygen (DO), Electrical Conductivity (EC), Nitrate (NO3-), Chloride (CL-), Iron (Fe), sulfate (SO4-2), phosphate (PO4-3), Ammonium (NH₄⁺) and (pH) satisfied the wastewater standard of Environment Organization of Iran and effluent discharging to surface waters was characterized by high quality on the Water Quality Index (WQI). As the result of the principal component analysis, TH, Fe, TSS, and DO, were the most influential parameters in the first component and SO4-2 in the second component, in measuring the wastewater quality variation. A significant increase from inlets to outlets was observed for (pH), total suspended solids (TSS), total dissolved solids (TDS), phosphate (PO4-3), and total hardness (TH) (p<0.05) due to no effluent treatment processes and intense culture at the fish farms and implies a Wastewater treatment system for removing suspended solids, pH control, and reducing TH and TDS.

This study aimed to investigate the effect of dietary fatty acid composition on growth performance and some hepatopancreatic enzymes under temperature stress and hypoxia in western white shrimp (Litopenaeus vannamei). For this purpose, 27 tanks with a volume of 300 liters, the density of 15 shrimps with 3 types of diets under 3 stress treatments (1: no challenge to environmental stresses; 2: with hypoxic stress (2±1 ppm); 3: with increasing temperature stress (36±2 °C). After the end of the experimental period, the highest survival rates in treatments 1 and 3 were 91.11 and 86.67%, respectively. The obtained results showed that the consumption of diet 1 compared to diet 2 shows a 90% survival rate. There was a significant difference in specific growth rate between treatments so that the highest rate was obtained in treatment 1 and the lowest in treatment 2 (p<0.05). The results of the physical and chemical parameters of water on different days showed that there was no significant difference between different treatments (p<0.05).The results of aspartate amino transferase (AST) in different treatments showed that there is a significant difference between the amount of AST in different diets before and after environmental stress (p>0.05). In shrimp fed with diet 2, the amount of enzyme during temperature stress (285.83±17.7 IUL) showed the highest increase in the amount of enzyme titer, which was more than 3 times the amount of enzyme in pre-stress conditions. Based on the results, the amount of alanine amino transferase (ALT) in shrimp fed with diets 2 and 3 increased sharply. Also, the measurement results of this enzyme in different treatments were significantly different (p>0.05). Generally, it can be concluded that shrimp fed a diet with 7.02% of total fat, total saturated fatty acids (5 g per 100 g of food), and total unsaturated fatty acids (13 g per 100 g of food) had the highest survival rate and higher specific growth under adverse environmental conditions.

This study was conducted to evaluate the effect of dietary administration of citric acid and lemon juice (Citrus limon) on growth performance, serum, and mucus immune responses, related-genes expression of growth (GH, IGF-I), and immune (Lyz, IL-1) in common carp (Cyprinus carpio). In this study, 300 common carp (mean weight 15±0.4 g) were randomly distributed between fifteen, 300 l fiberglass holding tanks. The fish were fed in five groups (each with three replicates) containing 0.5 and 1% citric acid, 0.5 and 1% lemon juice per kg feed, and also control with a basal diet without additives for eight weeks. Obtain results showed that fish fed with the diet containing citric acid had significantly higher growth indices compared to the control group (p<0.05). Also, the results indicated a significant increase in the innate immune responses including serum and mucus immunoglobulin and lysozyme, when the diet was supplemented with 1% citric acid (p<0.05). The levels of alanine aminotransferase and Glutathione S-transferase enzymes showed a significant reduction in the fish fed with additives, while the activity of alkaline phosphatase and lactate dehydrogenase enzymes were significantly reduced in the fish fed with a diet containing 1% citric acid (p<0.05). Regarding the genes expression, results revealed that the growth (GH, IGF-I) and immune (Lyz, IL-1) genes were significantly influenced by dietary supplementation, indicating that the genes expression were increased in compared to the control group (p<0.05). In conclusion, the results of this study showed that dietary administration of citric acid and lemon juice, especially 1% citric acid, have been improved the growth and some immune indices in common carp.

Studies on nutrient utilization and growth performance of Beluga (Huso huso) raised on five feeding schedules (treatment 1 continuously fed plant protein diet, treatment 2 continuously fed fish meal diet, treatment 3 alternate feeding of a 1-day plant protein diet; followed by a 1-day fish meal diet, treatment 4 plant protein diet in the morning fallowed by fish meal diet in the afternoon and treatment 5 fish meal diet in the morning followed by plant protein diet in the afternoon) in 3 replication (20 fish in each repetition) under laboratory conditions showed that continuous feeding with Fish meal diet (treatment 2) resulted in maximum growth, which was not significantly different from treatments 4 and 5 (p<0.05). While feeding with plant protein diet (treatment 1) and feeding every other day (treatment 3) led to a decrease in fish growth performance (p<0.05). In terms of protein digestibility, the best treatments were 2, 4 and 5, which did not show any significant difference with other treatments (p<0.05). The highest amount of muscle arginine belonged to treatments 2, 4 and 5, which was significantly higher than muscle arginine of fish fed with treatments 1 and 3 (p<0.05). Also, the highest amount of glycine was observed in treatment 5, which was not significantly different from other treatments except treatment 1. No significant difference was observed in the amounts of other muscle amino acids of the experimental treatments (p<0.05). The obtained results showed that the alternating change of the dietary protein source during one day (morning and evening and vice versa) does not have any negative effect on the growth performance and feed efficiency, and in most of the nutritional factors, it is equal to the treatment fed with fish meal.

This study was conducted with the purpose of investigating the addition of different concentrations of selenium and iron nanoparticles to the diet and its effect on the values of growth indicators and the percentage of carcass chemical compounds in rainbow trout (Onchorhynchus mykiss). In this research, 240 rainbow trout with an average weight of 5.21 ± 0.02 grams were fed for 8 weeks with diets containing 0.5, 1, 2 mg/kg of selenium nanoparticles in amounts of 10, 30 and 50 mg. iron nanoparticles in a completely randomized design to 4 experimental treatments; Treatment 1 (control group), treatment 2 (0.5 Se + 10 Fe), treatment 3 (1 Se + 30 Fe) and treatment 4 (2 Se + 50 Fe) were each divided by 3 repetitions and fed as free ions. According to the results, the values of body weight, percentage of weight gain, specific growth rate and protein efficiency ratio in the amount of 2 mg of selenium nanoparticles and 50 mg of iron nanoparticles increased compared to other values and had a significant difference with other treatments (p<0.05). Also, food conversion coefficient, in amounts of 2 mg of selenium nanoparticles and 50 mg of iron nanoparticles, had a significant difference with other treatments (p<0.05). In carcass analysis, the highest amount of protein was found in the treatment of 0.5 mg/kg of selenium nanoparticles and 10 mg of iron nanoparticles, which was significantly different from the control treatment (p<0.05). And by increasing the amount of selenium and iron nanoparticles in the experimental treatments, the amount of protein increased. Also, in terms of the amount of fat, a significant difference was observed between the experimental treatments and the control treatment (p<0.05). The results showed that the use of 2 and 0.5 mg of selenium nanoparticles and 10 and 50 mg of iron nanoparticles has a good effect on rainbow trout.