Differences in composition and fatty acid contents of different rainbow trout (Oncorhynchus mykiss) strains in similar and contrasting rearing conditions

Fatty acid (FA) composition and contents of fillets of seven strains of rainbow trout Oncorhynchus mykiss, reared in the same farm and sampled at the same time were studied. Three strains were compared with those from another farm as well as with outbreed and wild fish of the same fish species. In general, FA composition of farmed fish reflected their diet composition. Nevertheless, a genetics factor (belonging to a certain strain), also was found to contribute to fish FA composition. Rainbow trout of strain Steelhead appeared to have comparatively higher ability to regulate their FA composition, in particular, to retain high contents of physiologically important eicosapentaenoic (20:5n-3, EPA) and docosahexaenoic (22:6n-3, DHA) acids in biomass despite variations of their diet contents. Differences in contents of the EPA + DHA of different strains, found in this study, likely provided evidence for a potential of selective breeding of rainbow trout strains with a high EPA and DHA, which are of key importance for humans' diet. Besides, FA markers, which allow differentiating wild and farmed rainbow trout, were revealed.