Iranian South Medical Journal (Feb 2008)
The effect of using different concentrations of flaxseed oil instead of fish oil in the diet of rainbow trout for increasing n-3 fat in their tissue
Abstract
Background: Sea fish oils are rich in n-3 fatty acids, these oils are useful in treatment of diseases. The majority of clinical health benefits of n-3 fatty acids belongs to Docosahexaenoic acid (DHA) and Eicosapentaenoic acid (EPA). These two compounds are found only in fish tissue. The aim of this study was to use flaxseed oil as a precursor in the production of DHA and EPA in the Oncorhynchus mykiss tissues. Methods: Rainbow trout fishes with average weight of 6.150 ± 0.240 gr were stoked in polyethylene tanks with the capacity of 250 liters and reared in a randomly 3 repeats form. A diet containing 25, 50, 75 and 100 % flaxseed oil were prepared and given to the fishes bond on their biomass which was determined every 20 days. During the period of investigation, different parameters were measured as follows: water temperature 15 2˚C, pH=7.500-7.850, dissolved oxygen (saturated level), electrical conductivity=2800qm/cm and salinity 1.4 g/l. Results: By increasing the amount of flaxseed oil in the foods given to the fishes, the percentage of crude fat, the body protein and total fatty acids of n-3 type were significantly increased. The maximum change was in EPA type. There was no significant change in the final weight and growth rate of the fishes (p<0.05). Conclusion: We conclude that a diet containing 75% flaxseed oil and 25% fish oil will provide the biological need of the fishes and better protein absorption, and will increase the percentages of the fatty acids of DHA and EPA up to two times in the tissues.
