Potential of plant oils as alternative to fish oil for live food enrichment: effects on growth, survival, body compositions and resistance against environmental stresses in rainbow trout, Oncorhynchus mykiss

Enrichment of live foods by essential nutrients such as highly unsaturated fatty acids is an important tool for improvement of larval fish quality. In this study, nutritional effects of Artemia urmiana enriched by fish and plant oils on growth, survival rate, body compositions and resistance against thermal, salinity and hypoxic stresses in rainbow trout, Oncorhynchus mykiss were examined. Six food treatments comprising a commercial feed, non-enriched Artemia nauplii and the nauplii enriched by either of fish, sunflower, canola and soybean oils were used in triplicates. The fish fed with Artemia enriched by fish, sunflower and canola oils had significantly higher (p<0.05) survival rate, total length, wet and dry weights, specific growth rate and lower food conversion ratio than those fed the commercial feed. However, there were no significant differences in growth indices between the fish fed fish oil-enriched and plant oil-enriched Artemia. Minimum eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were reported in the fish fed with the commercial feed, while maximum EPA and DHA were in the fish fed canola oil-enriched and nonenriched Artemia, respectively. The fish fed canola oil enriched Artemia had significantly higher (p<0.05) resistance against environmental stresses compared to fish fed the commercial diet. Results showed that the plant oils, mainly canola and sunflower oils can be used for Artemia enrichment as a suitable substitute for the more expensive and rare fish oil for improving growth and resistance to environmental stresses in rainbow trout larvae.