Abstract

Considering algae as novel dietary ingredient for aquafeeds, this study evaluates the effects of three algae,Ulva rigida,Crassiphycus corneus(formerlyHydropuntia cornea) andScenedesmus almeriensis, on non-specific immune response and fatty acid profile in juvenile Nile tilapia (Oreochromis niloticus) after a short dietary administration period (30 days).U. rigida,C. corneusandS. almeriensisdiets (UL-25, CC-25 and SC-25 respectively) included 25% dry algae biomass, whereas an algae-free diet was used as control. Biological samples were taken at 7, 15 and 30 days. Diet SC-25 significantly improved respiratory burst, alternative complement (ACH50) and lysozyme activity (p .05). Regarding tissue fatty acid composition, SC-25 diet reduced the levels of saturated fatty acid in liver and muscle, while increased levels of C20:3n6 and eicosapentaenoic acid (EPA) in liver, and total n-3 content, arachidonic acid (ARA), EPA and docosahexaenoic acid (DHA) in muscle (p .05). UL-25 and CC-25 groups showed the lowest levels of ARA in liver but increased levels of monounsaturated fatty acids. In conclusion, the results obtained lead us to consider the use of a short pulse of dietary algae is suited for improving the immune response and modulating the tissue fatty acid composition in this fish species.