Maintaining Production Performance of Rainbow Trout While Reducing Reliance on Fish Oil-Based Feeds

Static landings and increasing cost of fish oil have led culturists to investigate alternative lipids and feeding strategies in order to reduce production costs and pressure on reduction fisheries. Rendered fats, like beef tallow, may prove to be suitable alternatives that could maintain production performance and allow tissue fatty acid profile to be conserved or restored utilizing fish oil-based feeds.  Accordingly, we evaluated fish oil sparing with beef tallow (50, 75 or 100% replacement of added fish oil) in feeds for rainbow trout fed for a total of 31 weeks in combination with 4, 8, or 12 weeks of finishing with a fish oil-based feed. Fish oil replacement and finishing duration had no significant effect on production performance: survival – 91.5 ± 1.3%; final weight – 587.7 ± 13.1 g; weight gain – 1151 ± 29%; FCR – 1.49 ± 0.03; SGR – 1.15 ± 0.01 %BW/day; feed intake – 2.19 ± 0.02 %BW/day. Based on these results, beef tallow may spare fish oil without negative effects on production, while reducing costs and reliance on marine resource-based feeds. However, these regimens may affect fillet and tissue fatty acid composition, which will be discussed in terms of physiological robustness and consumer acceptability of fillets.