Passos, RicardoCorreia, Ana PatríciaFerreira, InêsPires, PedroPires, DamianaGomes, EmmaCarmo, Beatriz doSantos, PauloSimões, MarcoAfonso, CléliaBaptista, Teresa2021-08-102021-08-102021Ricardo Passos, Ana Patrícia Correia, Inês Ferreira, Pedro Pires, Damiana Pires, Emma Gomes, Beatriz do Carmo, Paulo Santos, Marco Simões, Clélia Afonso, Teresa Baptista, Effect on health status and pathogen resistance of gilthead seabream (Sparus aurata) fed with diets supplemented with Gracilaria gracilis, Aquaculture, Volume 531, 2021, 735888, ISSN 0044-8486, https://doi.org/10.1016/j.aquaculture.2020.7358880044-8486http://hdl.handle.net/10400.8/6055This study had the support of Fundação para a Ciência e Tecnologia (FCT), through the strategic project UIDB/04292/2020 granted to MARE, and the project MAR-02.01.01-FEAMP-0084.Aquaculture intensification turns the reared populations prone to disease outbreaks, leading the industry to use antibiotics and chemotherapeutics. As the industry is searching for solutions, the development of sustainable aquafeeds with immunostimulant properties is emerging. This work aimed to assess the health benefits of Gracilaria gracilis as a supplement in Sparus aurata feed as well as its protective effect in a bacterial challenge. G. gracilis supplementation improved growth performance and influenced the haematological profile, namely in the constitution of the leukocytic population and erythrocytes size. Algae powder supplementation did not compromise the hepatic antioxidant systems and intestinal health and morphology were not affected by the algal supplementations. Algal extract improved lysozyme plasmatic concentration and a 5% algae powder inclusion was able to successfully protect the fish against a Photobacterium damselae subsp. piscicida infection, granting a 95% survival. In general, a 5% G. gracilis powder diet supplementation was able to improve growth, health, and bacterial resistance in gilthead seabream.engAquacultureBacterial challengeDietary supplementationFish welfareSeaweedjournal article10.1016/j.aquaculture.2020.735888