AUTHOR=Mota Cátia S. C. , Pinto Olívia , Sá Tiago , Ferreira Mariana , Delerue-Matos Cristina , Cabrita Ana R. J. , Almeida Agostinho , Abreu Helena , Silva Joana , Fonseca António J. M. , Valente Luisa M. P. , Maia Margarida R. G. 

TITLE=A commercial blend of macroalgae and microalgae promotes digestibility, growth performance, and muscle nutritional value of European seabass (Dicentrarchus labrax L.) juveniles

JOURNAL=Frontiers in Nutrition

VOLUME=Volume 10 - 2023

YEAR=2023

URL=https://www.frontiersin.org/journals/nutrition/articles/10.3389/fnut.2023.1165343

DOI=10.3389/fnut.2023.1165343

ISSN=2296-861X

ABSTRACT=Algae can leverage aquaculture sustainability and improve the nutritional and functional value of fish for human consumption. This study aimed to evaluate the potential of a commercial blend of macroalgae (Ulva sp. and Gracilaria gracilis) and microalgae (Chlorella vulgaris and Nannochloropsis oceanica) in a plant-based diet up to 6% (dry matter basis) on digestibility, gut integrity, nutrient utilization, growth performance, and muscle nutritional value of European seabass juveniles. Fish (11.3 ± 2.70 g) were fed with isoproteic, isolipidic, and isoenergetic diets: i) a commercial-type plant-based diet with moderate fish meal (125 g kg-1 DM basis) and without algae blend (control diet; Algae0), ii) control diet with 2% algae blend (Algae2), iii) control diet with 4% algae blend (Algae4) and iv) control diet with 6% algae blend (Algae6) for 12 weeks. The digestibility of experimental diets was assessed in a parallel study after 20 days. Results showed that most nutrients and energy apparent digestibility coefficients were promoted by algae blend supplementation, with a concomitant increase in lipid and energy retention efficiencies. Growth performance was significantly promoted by the algae blend, the final body weight of fish fed Algae6 being 70% higher than that of fish fed with Algae0 after 12 weeks, reflecting the up to 20% higher feed intake of algae-fed fish and the enhanced anterior intestinal absorption area (up to 45%). Whole-body and muscle lipid contents were increased with dietary algae supplementation levels by, respectively, up to 1.79 and 1.74 folds in Algae 6 compared to Algae0. Even though the proportion of polyunsaturated fatty acids was reduced, the content of EPA and DHA in the muscle of algae-fed fish increased by nearly 43% compared to Algae0. The skin and fillet color of juvenile European seabass were significantly affected by dietary inclusion of the algae blend but changes were small and in the case of muscle meeting the preference of consumers. Overall results highlight the beneficial effects of the commercial algae blend (Algaessence®) supplementation in plant-based diets for European seabass juveniles but feeding trials up to commercial-size fish are needed to fully assess its potential.