A short pulse of dietary algae boosts immune response and modulates fatty acid composition in juvenileOreochromis niloticus

Abstract

Considering algae as novel dietary ingredient for aquafeeds, this study evaluates the effects of three algae, Ulva rigida, Crassiphycus corneus (formerly Hydropuntia cornea) and Scenedesmus 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. corneus and S. almeriensis diets (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.

Effects of a short pulse administration ofUlva rigidaon innate immune response and intestinal microbiota inSparus auratajuveniles

“…The chemical parameters were determined weekly. Fish were hand fed twice per day (09:00 and 17:00 hours) at a rate of 2.5% of their body weight over a 30-day period (García-Márquez et al, 2020).…”

“…Serum was obtained after clotting of blood samples at room temperature (for 60 min) and subsequent centrifugation (3000 g, 20 min, 4 °C) (García-Márquez et al, 2020), and stored at −20°C until use.…”

“…Head kidney phagocytes were isolated following the methodology described by Secombes (1990) with modifications by García-Márquez et al (2020). In brief, the tissues were homogenized and filtered using a 100 μm nylon mesh with Leibovitz medium (L-15) containing 2% foetal calf serum (FCS, Sigma-Aldrich), 1% penicillin-streptomycin (Sigma-Aldrich), 0.1% (5 mg/ml) gentamicin (P/S/G) (Sigma-Aldrich) and 10 U heparin ml −1 .…”

“…and at 550 nm (A 550 ), respectively, in a UV-1601 spectrophotometer (Whitakker Bioproducts) following the methodology described by Secombes (1990) and García-Márquez et al (2020). Rico et al (2016).…”

“…The use of immunostimulants to enhance the non-specific immunity and to prevent the bacterial diseases has been evaluated (Yengkhom et al, 2018). In this context, immunomodulatory activity has been previously described after dietary administration of algae to farmed fish (Fumanal et al, 2020;García-Márquez et al, 2020;Valente et al, 2016).…”