جستجوی مقالات مرتبط با کلیدواژه « درجه حرارت » در نشریات گروه « شیلات »

This study aimed to investigate the effects of different temperatures (20, 27 and 33 °C) and two feeding rates (2.5 % biomass per day and satiation) on growth performance, body composition, hematology and blood biochemistry of Asian sea bass (Lates calcarifer). For this purpose, 8 fish with an average initial weight of 99.55 ± 0.24 g were randomly transported to 200 liters tanks (6 treatments with three replicates) and fish feeding was done using a commercial feed for 6 weeks. At the end of the experiment, the growth performance, blood indices and chemical composition of fish carcasses were measured. The results of this study showed that the feeding rate of biomass (2.5%) and satitation had no significant effects on growth performance and nutrition of this fish (P<0.05). However, different levels of temperature showed a significant effect on these indices (P <0.05). The average final weight of fish grown at 33 °C and fed at the biomass level was higher than other treatments, although this difference was not significantly different from that of the stored group at 27 °C. Among the hematology parameters, the number of red blood cells showed significant changes among treatments (P<0.05). Plasma biochemical parameters such as triglyceride, glucose and cholesterol level were significantly affected by water temperature and feeding rates (P <0.05). The activity of liver enzymes in plasma was not significantly different in different treatments (P <0.05). The protein and lipid content of fish carcasses increased with increasing temperature so that the group stored at 33 °C had the highest protein and lipid content (P <0.05). In general, the results of this study showed that temperatures above 27 °C are more optimal for this species and the feed rates of biomass and satiation have no significant effect on the growth and health performance of this fish in this temperature range.

The aim of the present study was to extract gelatin from the skin of farmed great sturgeon at different temperatures, hydrolysis using Alcalase enzyme, and to measure molecular weight distribution of peptides, amino acid composition and antioxidant activity of hydrolysates.

After removing pigments and non‐collagenous proteins, defatting, and swelling of triple‐helix structure, gelatin was extracted at the temperatures of 50, 60, 70, and 80°C for 6h and then hydrolysed using Alcalase (E/S ratio of 1:20w/w) for 3h. Molecular weight distribution of peptides, amino acid composition and antioxidant activity of hydrolysates were determined in different models.

Degree of hydrolysis (DH) reached its maximum within the first 30min in all samples. The highest DH was in the 80°C. There were no significant differences among hydrolysates with regards to amino acid composition and peptide molecular weight distribution. Hydrolysates produced at the extraction temperature of 60°C showed that the content of small peptides (molecular weight<1kDa) and total amino acids (g/100g) were slightly higher compared to other samples. This could influence antioxidant activity. At higher extraction temperature of gelatin, the efficacy of hydrolysates in preventing the loss in total sulfhydryl groups content was decreased (p<0.05) while there was no effect on TBARS and surface hydrophobicity (p<0.05).

Extraction temperature of gelatin did not reveal a considerable effect on properties and antioxidant activities of the resulting hydrolysates and gelatin hydrolysates with antioxidant activity and rich in peptides with molecular weight less than 1kDa could be produced at 50°C.

This study was designed to determine the effects of parameters: temperature, pH and dKH on growth indices of Oscar fish (Astronotus ocellatus). For this purpose, in each aquarium, there was specific combinations of temperature, pH and dKH, using design of experiment with Design Expert 7.0, and in total 14 combinations or treatments, each with 3 repetitions and thus, 3 fishes were entered in each aquarium randomly. In timespan 1-30 days, the measurement of body weight and body length was done, and growth indices including: weight gain (WG) and length gain (LG) were identified. Studying of growth pattern showed that the best mathematical model to show the changes of growth indices was quadratic equation. Carbonate hardness had the most effects on weight changes. The optimum temperature was 23-26˚c, pH was 6.7-8.3 and dKH was 5-6. Growth pattern according to length gain, was quadratic equation. Carbonate hardness had the most effects and the optimum range was similar to optimum condition for weight gain.

The aim of this study was to investigate the effects of temperature, pH and orange essential oil on reducing the growth rate of L. monocytogenes. The variables included 45 ° C (for 144 hours), 50 ° C (for 72 hours), 55 ° C (for 6 hours), 4 pH levels (4, 5, 6) and essential oil citrus (Citrus aurantium L.) in 0.2, 0.4 and 0.6% levels on the growth rate of L. monocytogenes in cold smoked silver carp fillet. The results showed that the number of bacteria increased with increasing pH at the studied temperatures (P<0.05), But correlation analysis showed no correlation between L. monocytogenes and pH. The increase in temperature significantly reduced the number of bacteria in cold and hot smoked silver carp fillets, so that the lowest bacterial count in both cold and hot smoked fillets was counted in a temperature of 55 ° C. The correlation between number of bacteria and temperature also confirmed this. Regarding the effect of citrus essential oil on the number of bacteria, the results showed that in the conditions of pH and constant temperature, increasing the percentage of essential oil, the number of L. monocytogenes decreased and this decrease, especially in the treatment of 0.6% of orange essential oil. Also, at the same temperature and pH, hot smoking compared to cold smoking was more effective in reducing the number of L. monocytogenes. Given that the number of bacteria counted in both methods of smoke at different temperatures and pH was not higher than the107 Log cfu/ g standard, it could be argued that smoke is a reliable way to increase the shelf-life of silver carp fillet and the best temperature and time to smoke was 55 ° C for 6 hours, at pH = 4, and essential oil level was 0.6%.

When aquatic organisms expose to the stress condition, many processes of physiological, biochemical and molecular are changed undesirable, which one of them is heat shock proteins (HSP) expression. HSPs are unique group of proteins which act as a defensive barrier while expose under stress conditions results in degradation or deformation of proteins preventing. HSPs are significantly important in aquatic organisms. Since the farmed aquatic organisms are enabled to adapt the environmental stressful conditions, including temperature and pathogenic stressors. Although increasing level of this group of proteins is mainly observed by increasing temperature, however their expression has also been reported in response to low temperature. Increasing the level of these proteins can increase growth, survival and resistance to environmental stressors. In aquaculture, by artificial stimulation of production in this group of proteins or supplying feed containing HSP, the immune system can be improved against pathogens, and even as an alternative to antibiotics and vaccines in the aquaculture industry. This study reports the role and function of HSPs in aquatic organisms in aquaculture conditions.

Aims: In recent years, marine fish farming has been one of the most important aquaculture activities in tropical regions, and their cultivation has grown considerably in most parts of the world. Thus, this study aimed at investigating the effects of different water temperatures on growth performance, biochemical body composition, and hematological indices of Asian sea bass (Lates calcarifer).
In the present experimental study, 3 temperature treatments, including 20, 27, and 33°C with 3 replications for 6 weeks were run on 8 sea bass fish, which were randomly transported to 500 liter tanks and fish feeding was done, using commercial concentrate food. At the end of the experiment, the growth performance, hematological indices, and biochemical body composition of the fish were measured. The data were analyzed by SPSS 18 software, using one-way ANOVA and Duncan tests.
Findings: The final weight of the fish reared in 27°C was significantly higher than the other 2 treatments. Specific growth rate, weight gain, feed intake, and protein efficiency ratio of 27 and 33°C were significantly higher than 20°C group. Hematological parameters did not show significant differences. Among the hematological biochemical compositions, glucose and cholesterol were significantly affected by temperature. The activity of liver enzymes in the reared fish plasma and the biochemical body composition of the fish (fat, protein, ash, and moisture) were not significantly different.
The temperatures of 27 and 33°C are suitable for Asian sea bass farming in sea water. Hematological indices and chemical body composition of the fish are not affected by different temperatures.

Ever since the Artemia as per live feed shows an important role in the most ornamental fish feeding, so aninvestigation on optimal growth and survival conditions of this favorable species would be very important for its breeding and propagation. In this research the in vitro effects of water temperature and And two concentrations of algal cells Dunaliellas alinain order to study the survival and longevity of adult Artemia urmiana from mating to the death has been investigated At two different temperatures and 60 ppm of salinity in through four treatments. The One-way ANOVA analysis illustrated that there was no significant statistical difference amongs treatments in case of longevity during reproduction. Also, in high concentrations of algae- both temperature range- it seems that the longevity have fallen. Although the statistical analysis revealed no significant relationship between longevity or the survival of Artemia at different temperatures, the results obtained from the effect of temperature factor showed that the longevity during reproductive period was higher in 20° C in comparison with 27° C.

The present study carried out an in vitro experiment on effects of salinity and temperature on Acartia tonsa life cycle from Caspian Sea. During the experiment, temperature and salinity ranged 25, 27, 29 ± 1 °C and 12‰ and 17‰, respectively within a period of 60 days. Spawning rate was measured using mesh size of 100 µ planktonic net from surface to 10 m depth. Early results show that nauplii arrive to adult stage during 8-10 days. Significant differences in nauplii and copepodites stage were found also in different salinities and temperatures. High survival and spawning rate were also found in 17 ‰ and 29 °C (P

In this study, the acute toxicity of Cypermethrin insecticides on caspian kutum fry (Rutilus frisii Kutum Kamensky, 1901) with the weight of 3 ± 1 g (average ± SD) in three different temperatures (15 °C, 20 °C and 25 °C) measured. The aim of this study was to determine the lethal concentration of 50 % of fish population within 96 hours. According to O.E.C.D standard methods, Experiments conditions were static and lasted for 4 days (96 h). Water physico-chemical parameters such as pH, total hardness, dissolved oxygen and temperature mesearued During the experiment. To find out cypermethrin cytotoxic range, 10 sea kutum fry were placed in each 20 Litre aquarium and aerated during the experiment. After obtaining leathal concentration final experiment started with 6 treatment and 3 repeatation. The values of LC10, LC30, LC50, LC70, LC90 and LC99 at 24, 48, 72 and 96 hours for all three temperature treatments obtained By using probit analysis, and Cypermethrin acute toxicity (LC50 96-h) for caspian kutum fry at 15 ± 1 ºC, 20 ± 1 ºC and 25 ± 1 ºC was 1.54, 1.49 and 1.30 micro grame per Litre, respectively. Results showed that by increasing the temperature Cypermethrin toxicity increases and also more deaths occur. In this experiment, the Clinical signs such as caudal region bruises, abnormal breathing and fish irregular swimming observed.

Temperature is an important factor influencing fish reproduction and temperature changes significantly affect the physiological processes of fish life. In this study the effect of 6 different thermal treatments (fixed temperature, 20, 22, 24, 26, 28 and a treatment with raising temperature from 22 to 28 ° C) on reproductive indicators of female Rosy Barb (Puntius conchonius) was examined. Results of ANOVA and Duncan test (p 0.05). The results of this study indicate that the best temperature for Rosy Barb female reproduction is 28 ° C

Cell concentrations and growth rate of Dunaliella salina Teodoresco in light intensities of 50 and 150 μmol. photons.m-2.s-1 and temperatures 25 ± 0.5 and 31 ± 0.5 oC (mean ± SD) were studied. The algae was isolated from the Urumieh Lake and cultured in various treatments (n = 12). Algae cells were counted regularly using Thoma counting chamber in 3 replicates on daily basis. The curve of changes in population was plotted. The highest cell concentration (mean ± SD) of 4.8 ± 0.6 × 10 6 cell.ml-1 was observed in light intensity of 150 μmol. photons.m-2.s-1 and temperature 25 ±0.5 oC. The minimum cell concentration (2.8 ± 0.3 × 10 6 cell.ml-1) was observed in light intensity of 50 μmol. photons.m-2.s-1 and temperature 31 ± 0.5 oC. The maximum growth rate (0.38 d-1) was recorded in light intensity of 150 μmol.photon.m-2.s-1 and temperature 25 ± 0.5 oC and the minimum (0.16 d-1) in 50 μmol.photon.m-2.s-1 at temperature 31 ± 0.5 oC Increase in temperature from 25 to 31 oC was found to be correlated with decrease in cell concentration and growth rate in D. salina., but increase in light intensities from 50 to 150 μmol. photons.m-2.s-1 resulted in increase of these factors.

This study was conducted to compare the effects of varying water temperatures on filtration rate of micro-algae Isochrysis affines galbana by Pinctada margaritfera spat on microalgae. To determine the optimum temperature and maximum filtration rate, 10 pearl oyster Pinctada margaritfera spats with mean total and total hinge length 32.67±2.76 and 31.57±2.90 respectively were stocked in 70 liter rectangular glass tanks supplied with filtered seawater. The spats were exposed to seven treatments of temperature including 18.5±0.21oC, 20.5±0.21oC, 23±0.1 oC, 24.5±O.31oC, 26.5±0.21 oC, 27.5±0.15oC and 28.5±0.21 oC with 3 replicates.
The results of filtration on Isochiysis affines galbana showed that the maximum filtration of spats on microalgae cells and water volume were 181,324,595 cells and 3626ml per hour and 635,031,212 cells and 12700ml per two hours in 27.5±0.15oC, respectively. The minimum filtration of microalgae cells and water volume were 5,224,028 and 104ml per hour and 65,874,413 cells and 13l7ml per two hours in 18.50±021oC, respectively. The results of this study demonstrated that the optimum tem perature for maximum feeding of spats on Isochrysis affines galbana is 27.5±0.15oC.