Preliminary Study on the Partial Substitution of Fish Oil with Amaranth Oil in diets for Rainbow trout (Oncorhynchus mykiss) Fingerlings: Effects on Body Composition and Fatty Acids Contents

摘要

The effect of the substitution of fish oil with amaranth oil in fish feed on body composition was studied in rainbow trout Oncorhynchus mykiss. Two experimental feeds, containing 7.2% and 5.0% of amaranth oil were used. The experiment was conducted in triplicate for each treatment (n=50). Initial body wet weight of experimental fish was 7.4±0.1 g. Feed was offered as 2.5% of fish biomass of respective group for 30 days. Chemical body composition and fatty acids composition were determined. No significant differences were found between the experimental groups and the control one. The highest specific growth rate (3.75%/day) was found in fish fed with feed containing the highest level of amaranth oil. The content of crude protein and crude fat in fish flesh was also highest in this group, 16.3% and 10.5% of body weight respectively. Fatty acids composition of fish fat was similar, however, higher content of amaranth oil in feed resulted in visible decrease of eicosapentaenoic acid (C20:5n-3, EPA) and docosahexaenoic acid (C22:6n-3, DHA) in fish fat.Our results indicate that amaranth oil can be a substitution of fish oil in feeds for rainbow trout, however, the study period of the experiment was relatively short and the fish number in experimental groups was rather limited. Hence, the results of the present trial might be considered as a preliminary study.