جستجوی مقالات مرتبط با کلیدواژه « fatty acid » در نشریات گروه « شیلات »

The microalga Nannochloropsis oculata is marine widely used in aquaculture systems as an essential source of protein, lipid, and polyunsaturated fatty acids. Day/night pH fluctuations driven by photosynthesis and respiration create an environment that exhibits changing pH ranges. The aim of this study was to find whether physical shocks could change the complete profile of nutrients (lipid, fatty acid, carbohydrate, chlorophylls, and proteins) in N. oculata. The algae were cultivated in 32 flasks of ten-liter for biomass production for 12 days using Guillard medium (f/2). The cells were reared at 0.5 molar salinity (29 ppt), under 3500 lux light intensity with a 12L:12D photoperiod and 21ºC temperature. After 12 days, when the cell density reached its stationary phase, they were centrifuged. The pellets were then re-suspended in fresh seawater thoroughly and transferred into thirty-two containers with 10-liter volumes, including eight treatments with four replicates. The algae in treatments 3, 4, and 8 were subjected to salinity (88 ppt), starvation, and pH (11) shocks, respectively and treatments 2, 5, 6, and 7 were subjected to salinity + pH + starvation, pH + starvation, salinity + pH and salinity + starvation shocks, respectively. The biochemical composition of N. oculata demonstrated that T3 at the end of the dark period, and T1 at the end of the light period, possessed significantly higher (51.51%), and lower (24.9%) lipid content, respectively. According to the results, EPA under pH shock, linoleic acid under pH + salinity + starvation shock, and DHA and omega-3 under pH + salinity shock at the end of the dark period revealed significant differences with the control group. The saturated fatty acids showed significantly higher value in the control group during the dark period. The monounsaturated fatty acids increased significantly under pH shock at the end of the light period on day 18. Based on the results, the best treatment to obtain more lipid production in N. oculata was using six-day salinity shock and harvesting algae at the end of the dark period, and for more EPA synthesis in N. oculata, pH shock for six days and harvesting the algae at the end of dark period is recommended.

The experiment was carried out for 120 days to determine the optimal dietary protein requirement for the growth of sandfish, Holothuria scabra. The experiment used 12 plastic containers sized 59×47×37 cm, and each container stocked 30 individual hatchery-produced sandfish juveniles (initial weight= 2.70±0.01 g). Experimental diets with different levels of protein, i.e., 10% (A), 20% (B), and 30% (C) as a treatment; it was as dry pellet with 3 mm diameters.  Sandfish were fed with experimental diets once in the afternoon at 2 % biomass. Results of the experiment showed that sandfish fed a 20% protein diet has the highest final weight (5.10±0.02 g), specific growth rate (SGR; 0.53±0.01 % day-1), and feed efficieny (FE; 62.48±0.13) and is significantly different compared to other treatments (p<0.05). On the other hand, feeding with different dietary protein levels did not influence the survival rate greatly (p>0.05), ranging from 85.00-95.83%. The total amino acid content of sandfish juveniles in treatment B was highest (6.62%) and followed by C (6.27%) and A (4.75%). Likewise, the highest fatty acid content was also found in treatment B (0.440%) followed by treatments A and C of 0.416%; 0.332% respectively.  Results of the present study found the best feed was treatment B at 20 % protein content. Moreover, based on statistical analyses, it is suggested that dietary protein requirement for maximum growth of juvenile sandfish is 16%.

Ephippia Moina macrocopa hatching relates to the quality of nutrients received by the parent. Increasing the quality of the parent feed can improve the quality of the nutrient in eggs (ephippium) and can increase hatchability. This study was conducted to examine the addition of fatty acids in the feed through replacing rice bran suspension with fishmeal suspension on the quality and quantity of ephippia M. macrocopa. The treatment in this research was a substitution of rice bran suspension with fishmeal suspension by 0, 15, 30, and 45%. This study indicated that substitution of rice bran suspension with fishmeal suspension of 30% and 45% in Moina culture produced the same ephippia production but with a higher degree of hatching. Moreover, the substitution of rice bran suspension with fishmeal suspension by 30% increased the concentration of n-3 fatty acids (1.15%) in the egg of ephippia M. macrocopa.

This study aimed to examine the effect of fatty acid in the diet on changes the incidence of the Red-head Syndrome under temperature stress and hypoxia in white leg shrimp (Litopenaeus vannamei) during 8 weeks. For this purpose, shrimps were fed  by 4 diets  (diet 1: containing 7.02% of total fat; diet 2: containing 6.41% of total fat; diet 3: containing 8.05% of total fat; diet 4: containing 6.41% of total fat with 1750 mg/kg of vitamin E), under 3 stressors (S1: no challenge to environmental stresses; S2: with hypoxic stress (2.0±1.0 ppm); S3: with increasing temperature stress (36±2°C). The results of the hypoxic stress on the incidence of redness in L. vannamei fed with different levels of fatty acids showed that there were differences significantly (p<0.05). Temperature increase although showed no differences between healthy shrimps(p>0.05) but, there were significant difference among red-headed shrimp in treatment 1, 2 and 3 (p<0.05). The examination in treatments 2 and 3 showed hepatopancreatic  were loss the columnar structure so thatelongated cells and dilated tubules were observed. Some B cells had no vacuoles and were not fully developed. The number of R cells was low and basophilic F cells were convex. In treatment 4, the cells have few reserves and were normal. Some B cells were degenerated. The height of the tubules was lower than normal, but no inflammatory reaction was observed in the tissue. In treatment 4, cell showed  better conditions than treatments 2 and 3. Accordingly, B cells were present well and R cells showed moderate storage. In general, it can be concluded that the use of vitamin E can reduce the complication of redness and minimal cell damage to hepatopancreatic tissue in L. vannamei.

The marine Copepoda species Oithona nana, is considered as one of the most Copepoda species that successfully mass cultured in marine hatcheries. This study investigated the effects of four feed diets (soybean, yeast, rice bran, and corn starch) on the population growth, growth rate, population composition, fecundity, and fatty acid composition of Copepoda, O. nana. The experiment was continued for 15 days and the copepods were fed on four feed diets with concentration of 1 g/106 individual/day. The results found that O. nana fed on corn starch showed the highest significant population growth (9067 Individual/L) and population growth rate (0.735). For nutritional value, copepods fed on rice bran were detected to have the highest content of monounsaturated fatty acid (MUFA), polyunsaturated fatty acids (PUFA), the lowest saturated fatty acids/unsaturated fatty acids ratio (SFA/UFA ratio) and the lowest SFA. More importantly, the rice bran diet was the only diet that showed eicosapentaenoic acid (EPA; C20:5ω3). Moreover, copepods fed on rice bran showed the highest significant female fecundity (8.33 egg/female), copepodite and nauplii percentages (33.27 and 32.65%, respectively). Finally, regarding to the quantity, corn starch is the most suitable diet for mass culturing O. nana, while, regarding to the quality, rice bran enhances the nutritional value and fecundity of the Calanoida Copepoda O. nana.

This study compared the efficacy of different diets on the population density, specific growth rate, doubling time, and fatty acids composition of the freshwater cyclopoid copepod Acanthocyclops trajani. The experimental diets consisted of fresh binary microalgae (Scenedesmus obliquus+Spirulina maxima), dry binary microalgae (S. obliquus+S. maxima), dry Gracilaria corticata, and mixed dry vegetables (including spinage, coriander, and parsley). Results have showed that the highest population growth rate (0.145), mean density (1445 ind L-1), and the shortest doubling time (4.76 d) have been obtained in copepods fed on dry binary microalgal diet. The amounts of fatty acids in A. trajani could be modified by feeding copepod with different diets. The amount of C22: 6n-3 (DHA) was significantly higher in copepods fed dry binary microalgae (3.75±1.08 %) compared to the other diets. This cyclopoid copepod had higher levels of EPA and DHA than those in corresponding diets, suggesting that the A. trajani is probably able to accumulate EFA (essential fatty acid). This study indicates the potential of using specifically dry microalgae to improve the nutritional composition in copepods as a suitable supplementary live food for freshwater fish larvae.

In this study, seasonal and sexual variations of fatty acid profiles of Pseudophoxinus fahrettini and Capoeta mauricii which are freshwater fishes in Turkey inland waters were investigated. The monounsaturated fatty acids (MUFAs) values were higher than saturated fatty acids (SFAs) and polyunsaturated fatty acids (PUFAs) values for both species. Also the ratios of MUFAs in P. fahrettini were higher than those of C. mauricii in all seasons. The results indicated that palmitic acid was the most dominant SFA for both species in all seasons. Oleic acid in the muscle of P. fahrettini and palmitoleic acid in the muscle of C. mauricii were the highest MUFA respectively in both genders in all seasons. The highest ratios of ω3 PUFAs were 23.00% in the muscle of C. mauricii in summer and 18.44% in P. fahrettini in winter. The ratios of ω3 PUFAs in muscles of both species and genders were higher than the ratios of ω6 PUFAs during all the seasons. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were significantly higher than the other PUFAs in both sexes of the species. The ratio of ω3 PUFAs to ω6 PUFAs was higher than 1.76 in both species and genders in all seasons.

Growth and survival of Polychaete, Nereis diversicolor fed on waste water of great sturgeon, Huso huso at different densities were studied. The study aimed to assess the efficacy of feeding of N. diversicolor with waste water derived from different densities of great sturgeon culture as well as to find a balance between fish density and growth of the worm. The worms (0.2-0.3 kg m-2) with an initial mean weight of 0.05 g were fed for 55 days with waste water of great sturgeon at densities of 2-3, 3-4 and 4-5 kg m-2 fish. A group of worms fed with fish feed was considered as the control. The obtained results showed that the biomass and average weight of the harvested worms were significantly higher at the density of 3-4 kg m-2 fish than in the other two treatments (p<0.05). Also, worms fed with fish feed (control group) showed higher survival rate and biomass production than the treatments. Some fatty acids were abundant in worms from the treatments, specifically 14:0, 16:0, C18:1n9c, 20:1, 22:1n-9, 18:3n-3, 20:2, 20:5n-3 (EPA) and 22:6n-3 (DHA), but were significantly lower than the control worms. The results demonstrate that production of N. diversicolor using fish waste water was highly efficient and can offer a sustainable solution to remove organic load in the aquaculture waste waters. Also, production of N. diversicolor via this method as an alternative source of fatty acids and protein for H. huso production could achieve multiple aims such as retention of valuable lipids from the H. huso waste water.

In this study rainbow trout (Oncorhynchus mykiss) fillets were vacuum packed, frozen and stored at -18°C and  the effect of this packaging method on proximate composition, fatty acids and amino acid profile and their changes compared to control conditions during 9 months of storage were studied. The results showed that 18 fatty acids were identified. The unsaturated fatty acid (UFA) were 56.77 and 57.23 % in control and vacuum packed samples in zero time and oleic acid and linoleic acid had high amounts among the UFA. The saturated fatty acid (SFA) were 29.51 and 29.31 in control and vacuum packed samples, respectively and stearic acid and palmitic acid were the most among the SFA. As a result of a frozen storage period of 9 months, a marked content decrease was found in the fatty acid groups such as MUFA, PUFA and ω -3 PUFA, as well as in the ω -3/ ω-6 ratio. However, a preserving effect on such fatty acid parameters could be observed due to the vacuum packed treatment. Results showed that moisture, ash, protein and fat content were 72.1, 2.27, 20.78 and 7.1 g/100g in fresh fillets. At the end of storage time moisture and protein content were decrease and fat and ash were increase in control and vacuum packed samples. On the other hand, the most abundant amino acids in rainbow trout fillets were glutamic acid, aspartic acid, arginine and leucine. The results indicate that vacuum packaging treatment, in all measuring factors had significantly reduced than those in control samples. Thus, vacuum packaging retain quality of fatty acid and amino acid of  rainbow trout fillets within the cold storage and utilization of this method is recommended.