Growth performance,nutrient digestibility and lipase activity in juvenile rainbow trout (Oncorhynchus mykiss) fed fat powder in diet containing emulsifiers (cholic acid and Tween‐80)

This research was conducted to investigate the effects of two dietary emulsifiers on nutrient digestibility and lipase activity in rainbow trout (Onchorhyncus mykiss). A basal rainbow trout diet containing fat powder supplemented with 10 and 5 g kg^?1 of cholic acid, and 20 and 40 g kg^?1 of Tween‐80. Control diet contained no emulsifiers with fat powder was replaced by fish oil. Each diet was randomly assigned to 1,500‐L tanks in triplicate. Juvenile rainbow trout with an initial weight of 27.32 ± 2.03 g were randomly distributed in the experimental tanks. The results showed that growth parameters did not change by the addition of the two emulsifiers (p > .05). Total triglyceride content was significantly higher in control fish fed diet containing fish oil (p < .05), while serum cholesterol content showed no significant differences among treatments (p > .05). Control diet resulted in a higher fat digestibility than those of other experimental diets. However, protein and ash digestibilities in diet containing emulsifier were higher than those of the control diet. Control group showed the lowest lipase activity, whereas 20 g kg^?1 Tween‐80 diet caused the highest lipase activity among treatments (p < .05). In conclusion, it seems that a higher lipase activity induced by the emulsifiers could not compensate for the negative impacts of fat powder on the experimental diets.     

Effects of total fish oil replacement to vegetable oils at two dietary lipid levels on the growth,body composition,haemato‐immunological and serum biochemical parameters in caspian brown trout (Salmo trutta caspius Kessler, 1877)

This research aimed to evaluate the effects of two dietary fat levels [low fat (LF) (10%), high fat (HF) (20%)] and sources [fish oil (FO), vegetable oil (VO)] on the growth and some physiological parameters of Caspian brown trout fingerlings for 60 days. Tuna oil or blends of canola and soybean oils (85:15) were added to diets to design four feeds namely LFFO, HFFO, LFVO and HFVO according to the fat levels and sources. The fish fed the LFFO diet had lower weight gain than the other fish (P<0.05). The total n‐6 fatty acids increased in fish fed diets with the blends of VO, while the total n‐3 fatty acids decreased in these fish (P<0.05). Serum lysozyme activity was higher in fish fed the HFVO diet than the other fish (P<0.05). Serum glucose, total cholesterol, triglyceride and very low‐density lipoprotein were lower in fish fed LFFO than the other fish (P<0.05). The present study demonstrates that in terms of fish growth, VOs can be used as an alternate source of dietary fat, whereas fish health and nutritional value are improved with the LFFO diet. According to these results, a partial substitution of FO by VO in high‐level fat diets is suggested for long‐term feeding of Caspian brown trout.     

The use of fenugreek seed meal in fish diets: growth performance,haematological and biochemical parameters,survival and stress resistance of common carp (Cyprinus carpio L.)

The present study was conducted to investigate the effects of fenugreek seed meal (FKSM) on growth performance, blood haematological and biochemical factors, survival and stress resistance of the common carp (2.46 ± 0.06 g) fingerlings. Four practical diets containing 0 (control), 0.5%, 1% and 1.5% FKSM were used to feed fish. Fish were fed on the tested diets at a rate of 3% of body weight for 8 weeks. Results indicated that fish fed the control diet had a significantly lower weight gain, specific growth rate and condition factor compared to the other treatments (P < 0.05). Feed conversion ratio decreased significantly in fish fed diets containing FKSM. There were no significant differences in glucose levels, red blood cell count, haematocrit and haemoglobin between treatment groups and the control group (P > 0.05). Significantly lower white blood cells count was observed in fish treatment with FKSM when compared with the control group (P < 0.05). The cholesterol level in group fed supplemented diet by 1% fenugreek significantly lower than other groups (P < 0.05). Total protein levels were significantly higher in all treatments compared to the control (P < 0.05). No mortality was recorded during the feeding trial. In salinity stress experiment, highest survival rate belong to fish fed supplemented diet by 1% fenugreek. These results indicate that FKSM can be considered as a beneficial dietary supplement for improving the growth performance and blood indices of common carp fingerling.     

In vitro oocyte maturation and blood‐circulating steroid hormones in Sterlet (Acipenser ruthenus) and Siberian sturgeon (Acipenser baeri)

The oocyte of Sterlet (Acipenser ruthenus) and Siberian sturgeon (Acipenser baeri) was evaluated after incubation with 17α, 20β‐Dihydroxyprogesterone (DHP) in artificial media. Concentration of testosterone (T), progesterone (P4) and 17‐β estradiol (E2) in blood and their relation to fertilization rate were measured during experimental period. The oocytes at the same developmental stages were incubated in SIS (based on sturgeon blood ionic composition), RM2 (Ringer solution modified for sturgeons) and L‐15 (Leibovitz medium) artificial mediums in the presence of 1 μg/ml of 17α, 20β‐Dihydroxyprogesterone for 12, 18 and 24 hr. The result of this study demonstrated that fertilization rate decreased with the increasing duration of incubation in all mediums. In the Siberian and Sterlet sturgeon, the highest fertilization rate was observed in the oocytes incubated in RM2 (0.81 ± 0.4) and SIS (0.44 ± 0.8) mediums for 12 hr respectively. In the Siberian sturgeon, fertilization rate decreased significantly (p < .05) with incubation time in all three mediums. In Starlet, fertilization rate decreased significantly (p < .05) with time and reached a minimum after 24 hr (0.16 ± 0.1) in L‐15 medium. No significant (p > .05) differences were observed between blood plasma hormones and fertilization rate. The results of this study indicated that 17α, 20β‐Dihydroxyprogesterone is essential for induction of in vitro oocyte maturation in these species.     

Biochemical and histological changes in the liver tissue of rainbow trout (Oncorhynchus mykiss) exposed to sub-lethal concentrations of diazinon

The organophosphate insecticide diazinon is widely used to control pest in Iran. The purpose of the present study was to investigate the antioxidant and histopathological changes in the liver tissue of rainbow trout (Oncorhynchus mykiss) exposed to 0.1 and 0.2 mg/L of a commercial formula of diazinon for a period of 28 days. Antioxidant enzyme activities—catalase, superoxide dismutase, glutathione peroxidase and glutathione reductase—were determined after 7, 14 and 28 days of exposure. Histopathological analyses were performed at the 28th day. All antioxidant enzymes were induced after 7 days of diazinon treatment in both concentrations of diazinon. Catalase and superoxide dismutase maintained elevated activities during all the treatment period. Glutathione peroxidase activity returned to the control values at the 14th day, decreasing to values below control at the 28th day in both diazinon concentrations. Glutathione reductase maintained increased activities at the 14th day in the 0.1 mg/L diazinon, decreasing to control values at the 28th day. In the 0.2 mg/L group, the activity returned to control values at the 14th and decreased below the control at the 28th day. Total antioxidant capacity of hepatocytes significantly decreased in fishes exposed to diazinon during all experimental periods. Hypertrophy of hepatocytes, vacuolization of cell cytoplasm and hepatocyte cloudy swelling were observed in the liver tissue of fish exposed to both concentrations of diazinon. The results showed that diazinon altered the activity of antioxidant enzymes and the cellular total antioxidant capacity inducing oxidative stress and cellular damage in hepatocytes evidenced by histopathological analysis.     

Effects of different salinity and temperatures on the growth,survival, haematocrit and blood biochemistry of Goldfish (Carassius auratus)

The aim of the present study was to investigate the effects of different salinities (0‰, 6‰ and 12‰) and temperatures (23, 27 and 31 °C) on the food consumption, growth, blood biochemistry and haematocrit of Goldfish. After 45 days of exposure to different salinities and temperatures, Goldfish showed a good adaptation to these salinities and temperatures in terms of blood biochemistry (glucose and triglyceride) and haematocrit. Salinities (0‰ and 6‰) and temperatures (23 and 27 °C) did not affect the weight gain, specific growth rate, final biomass and feed conversion rates, but these parameters were significant (P<0.05) at 12‰ salinity and 31 °C temperature. Plasma total protein levels decreased with the increase in salinity (P<0.05), while they were independent of temperature. In conclusion, Carassius auratus, a freshwater stenohaline fish, showed good growth in saline waters with maximum 12‰ salinity and 31 °C temperature.     

Effects of melatonin on oocyte maturation in PCOS mouse model

The purpose of oocyte in vitro maturation is generation of mature oocytes that could support future development. Efforts have been made to enhance oocyte developmental competence by developing optimal culture conditions. The present study is conducted to determine melatonin effects on quality of polycystic ovarian syndrome (PCOS) oocytes when it has been added during in vitro maturation, and immature oocytes were cultured in defined conditioned medium with and without different melatonin concentrations. Melatonin could significantly improve nuclear maturation of PCOS oocytes (81.1% vs. 56.3%, P < 0.05 were achieved with 10^?6 mol/L concentration). Cleavage rate was significantly higher in 10^?5 mol/L concentration compared to untreated oocytes in PCOS (54% vs. 35%, respectively) and it was significantly higher with 10^?6 mol/L concentration in the control group, 55% versus 38%, compared to untreated oocytes. This study showed that melatonin has the potential to induce oocyte nuclear maturation and guarantee fertilization potential. © 2016 Japanese Society of Animal Science