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- Effect on health status and pathogen resistance of gilthead seabream (Sparus aurata) fed with diets supplemented with Gracilaria gracilisPublication . Passos, Ricardo; Correia, Ana Patrícia; Ferreira, Inês; Pires, Pedro; Pires, Damiana; Gomes, Emma; Carmo, Beatriz do; Santos, Paulo; Simões, Marco; Afonso, Clélia; Baptista, TeresaAquaculture 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.
- Potential use of macroalgae Gracilaria gracilis in diets for European seabass (Dicentrarchus labrax): Health benefits from a sustainable sourcePublication . Passos, Ricardo; Correia, Ana Patrícia; Pires, Damiana; Pires, Pedro; Ferreira, Inês; Simões, Marco; Carmo, Beatriz do; Santos, Paulo; Pombo, Ana; Afonso, Clélia; Baptista, TeresaSeaweeds still possess a large undisclosed potential, mainly due to their constituent’s richness, which may have several uses for society. In aquaculture, they may play a role as an ecological sustainable aquafeed supplement to increase overall health and fight pathogenic outbreaks. This study aimed to evaluate the general health modulation that the inclusion of Gracilaria gracilis could accomplish in the diet of Dicentrarchus labrax. Dried algae at 2.5% and 5% and algal extract at 0.35% inclusion levels were supplemented to seabass diet to evaluate possible growth, haematological, immunological, antioxidant, metabolic, and intestinal morphological modulations. The supplementations did not impact growth or feed utilization, and barely affected the haematological profile and some metabolic parameters. Nevertheless, it caused a marked outcome on lysozyme, some oxidative stress biomarkers, and intestine morphology, suggesting beneficial consequences from the algal inclusion. Dried algae powder, with a 2.5% inclusion, boosted immune response, with higher plasmatic lysozyme and intestinal acid goblet cells and protected against oxidative damages by improved enzymatic and non-enzymatic responses. Thus, we provide evidence that dietary seaweed application may be a path towards a more sustainable aquaculture industry.
- Pelvetia canaliculata as an aquafeed supplement for gilthead seabream Sparus aurata: A biorefinery approach for seaweed biomass valorisationPublication . Pires, Damiana; Passos, Ricardo; Carmo, Beatriz do; Tchobanov, Carolina F.; Forte, Sara; Vaz, Mariana; Antunes, Madalena; Tecelão, Carla; Baptista, TeresaFor sustainable and economically viable aquaculture, it is necessary to search for alternative sources of aquafeeds. Algae have been studied because of their bioactive compounds with several activities such as antioxidants. The direct incorporation of the macroalgae Pelvetia canaliculata in sunflower oil to increase oxidative stability and biological value results in waste with high nutritional value that may be used as an ingredient in aquaculture feed. This study aimed to evaluate the effect of incorporating algae powder (PEL 1%, PEL 10%) and algae waste obtained after sunflower oil supplementation (WO 1%, WO 10%) in aquafeeds for gilthead seabream. We studied the growth performance, haematological profile, oxidative stress and metabolic parameters, and intestine histomorphology. Experimental diets did not influence growth performance or somatic indexes, and barely affected the haematological profile. Catalase showed higher activity in seabream fed with PEL10 than with control diet. Total glutathione had a higher activity in fish fed with both WO diets. Plasmatic levels of cholesterol were higher in PEL1 and WO10. Triglyceride levels were higher in WO1 and total lipids were higher in both WO diets. The histomorphology of the intestine was slightly modulated by experimental diets but was not affected negatively. In general, supplementation with Pelvetia powder and algal waste oil may be used as an aquafeed for gilthead seabream according to the results obtained for growth, some haematological parameters, catalase and total glutathione, intestinal villi length, and the number of total and acid goblet cells.