فصلنامه تغذیه آبزیان
سال هشتم شماره 2 (پیاپی 20، تابستان 1401)

In this study, the effects of garlic phytoestrogen extract on gonad maturation along with estrogen and progesterone levels in yellowfin seabream (Acanthopagrus latus) were investigated. A total of 60 yellowfin seabreams were caught from Naseri pond in Khuzestan Province, Southwest Iran and transported to the laboratory. Fish were treated in four groups receiving garlic extract with doses of 0 (control), 0.5, 1 and 2 % of diet (T1, T2 and T3, respectively). Each treatment consisted of three replicates. The fish were fed twice a day at 3% of body weight for 14 days. For histological study, samples were taken from the gonads. In order to assay the hormone levels, samples were taken from the caudal vein of the fish on days 0, 7, 10 and 14. The histological results showed that garlic extract in the lowest dose caused a decrease in vitellogenesis, however, in higher doses an elevation in vitellogenesis and also the tendency of this hermaphrodite fish gonads to be female. The highest amount of vitellogenesis was reported in T1 on 10th day. In total, elevating in the amount of this extract initially upraised the number of vitellogenic follicles and promotion of ovarian maturation. However, higher doses and also increasing the administration time of the extract exhibited inverse results. Measuring the levels of hormones showed a significant change in their plasma levels during the experiment, so that an increase in level of estrogen was observed in all three prescribed doses and an increase in level of progesterone was observed in higher doses (T2 and T3; p<0.05). The results of the present study indicate the effect of garlic phytoestrogen extract on growth and maturation of ovaries.

Biofloc technology is an environmentally aquaculture production system in which nutrients are continuously recycled and reused. In this technology, growth performance, water quality and production costs need to be considered. The objective of this study was to evaluate intensive culture of common carp (Cyprinus carpio) in indoor biofloc system (BFT). One biofloc treatment with minimum water exchange and one control with 30% renewal water in triplicates were managed. Fish (40 g in weight) were stocked in 400 L fiberglass tanks at a density of 2 kg/m3 and 18-week experiment was conducted. Mollasses was added to the biofloc tanks at a C:N ratio of 20:1. In this study, biofloc treatment exhibited significantly higher mean total ammonia, nitrite, nitrate, alkalinity, total suspended solid and lower pH than the control (p<0.05). Growth parameters and final biomass did not differ significantly between BFT and control. Feed conversion ratio was higher (p<0.05) in the control than in the BFT treatment. Water consumption/kg common carp produced in the control was 12 times higher than in the BFT group. It can be concluded that farming common carp in BFT system is more economic in saving great amount of feed and water with minimal discharge of pollutants without negative effects on carp growth.

This study investigated the effects of feed additive containing organic acids, cinnamaldehyde and permeabilizers on growth rate and intestine structure of whiteleg shrimp (Litopenaeus vannamei). So, five isoproteic (∼38%) diets containing different levels of 3, 6, 9 and 12 g/kg (T3, T6, T9 and T12, respectively) commercial additive Biotronic Top 3 were formulated and a diet without this additive were considered as a control. Shrimps (2.7 g in average weight) were randomly placed in fifteen 300-liter fiberglass tanks containing sea water (20 shrimps in each tank) and each experimental treatment was in triplicate. Shrimps were fed at the rate of 7% of their body weight three times a day. At the end of the experiment, the average final weight in shrimps fed with diets containing additives was significantly higher than the control group (p<0.05). The highest average final weight was observed in T3. However, the addition of higher levels of this additive did not show any significant effect on the final weight of shrimps (p>0.05). The food conversion ratio in the treatments fed with additives, (except for T9) was significantly lower than the control group (p<0.05). Examining the shrimp intestine showed that using this additive elevated the height of the intestinal villi. In general, according to the findings of this study, dietary supplementation of Biotronic Top 3 at 3 g/kg can enhance the growth rate and intestine histology of whiteleg shrimp.

Features such as providing energy, essential fatty acids needed by fish and aid to absorb fat-soluble nutrients have made fat an important influencing factor in aquaculture. Given the increased global consumption of fish oil in aquaculture, it will be difficult to supply it in the future. The inexpensive and easily available alternatives, which do not cause disturbance the growth of fish or fillet quality is the main challenge in the sturgeon feeding process. Vegetable oils are considered as the most noteworthy source of alternative fats in dietary formulations of fish. However, fish needs a certain level of fat, and fat in amounts higher or lower than this desirable level can be a threat to the growth and even the health of the fish. So, it is important to explore the optimal measure of dietary lipid for aquatic animals with high economic value. Hence, due to the biological importance (evolutionary, geographical, morphological, anatomical and physiological) and economic value (environmental, recreational, aquaculture) of sturgeon fish, it is necessary to investigate and research the type and optimal level of dietary lipids. This approach, by introducing different vegetable oils and using them in the nutrition of sturgeon, provides a more realistic understanding of the nutritional needs of these valuable species, which will help to better manage sturgeon stocks and their more sustainable production.

This study was conducted with the aim of determining the effect of different probiotics administration on alterations in biochemical parameters of juvenile sea bass (Lates calcarifer). Four hundred and twenty sea bass with an average weight of 34 ± 4.5 g were prepared and randomly divided into seven groups with three replications (40 fish in each replication) and fed with experimental diets for 90 days. The experimental treatments included: group 1 (T1): different Lactobacillus plantarum sp.; group 2 (T2): L. plantarum sp., L. bulgaricus, L. acidophilus and L. rhamnosus in a combined form (combination of lactobacilli); group 3 (T3): the combination of diets 1 and 2 as well as Bacillus cereus and B. thuringiensis which was administered to fish every two weeks; group 4 was the control group without probiotics (C4). In addition, groups 5, 6 and 7 (T5, T6 and T7) were similar to groups 1, 2 and 3 which were continuously fed to fish. The results showed that there was a significant increase in blood serum cholesterol at the end of the experiment in T7 compared to the control group. The calcium level in T3 showed the highest amount compared to other treatments. All treatments showed a decreased amount of total protein at the end of the experiment compared to the control (C4). Moreover, the highest value was related to T6. T7 exhibited the highest amount of triglycerides and glucose at the end of the experiment. In case of liver enzymes, the lowest serum ALP level was found in T1 and the lowest AST in T6, while serum ALT level did not display any significant difference in any group. In cases of Cpk and HDL, the lowest values belonged to T1. In general, it can be concluded that the use of a mixture of probiotics in a pulse administration can cause positive effects on the blood biochemical parameters of L. calcarifer.

The high price of fish oil increases the cost of fish feed. So, using vegetable oils can significantly reduce its cost. Therefore, this study was investigated the effects of replacing fish oil with corn oil in the diet on the growth performance and biochemical composition of R. kutum fingerlings. In this study, twelve 100-L fiberglass tanks were used, each containing 20 fingerlings (6.05 ± 0.6 g in average weight and 7 ± 0.3 cm in average total length). The fish fed with four diets with the same protein, fat and energy including: T0 (control treatment), 25, 50 and 75% replacement of corn oil (T1, T2 and T3). The fingerlings were fed three times for 8 weeks and based on 3% of body weight. At the end of the experiment, growth rate, physical and chemical characteristics of water and biochemical composition of the carcass were measured. In this study, no statistically significant differences were observed between the treatments in terms of food conversion coefficient, protein efficiency coefficient, specific growth rate, body weight gain, length increase percentage, average daily growth, condition factor, survival rate, initial length, final length, initial weight and final weight (p>0.05). There was also no significant difference between the treatments in terms of carcass moisture and ash (p>0.05). However, significant differences were found in terms of the fish protein and fat among the treatments (p<0.05). Hence, the replacement of corn vegetable oil up to 75% with fish oil does not exhibit any negative effect on the growth performance of R. kutum.