Potential use of macroalgae Gracilaria gracilis in diets for European seabass (Dicentrarchus labrax): Health benefits from a sustainable source.

Seaweeds 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.

Proximate Composition and Fatty Acid Profile of Gilthead Seabream (Sparus aurata) Fed with Pelvetia canaliculata-Supplemented Diets: An Insight towards the Valorization of Seaweed Biomass.

Seaweeds are a sustainable source of protein and lipids that may be used to replace fish by-products in aquaculture feed. This study aimed at using the macroalgae Pelvetia canaliculata as an ingredient in gilthead seabream (Sparus aurata) feed, either as freeze-dried powder or as algae residue (waste) that was obtained after the supplementation of sunflower oil. The formulated diets and the fish muscle were analyzed concerning the proximate composition and the fatty acid profile. The health lipid indices hypocholesterolemic/hypercholesterolemic (h/H), atherogenic (AI), thrombogenic (TI), as well as n-3/n-6 and polyunsaturated fatty acid/saturated fatty acid (PUFA/SFA) ratios were calculated. Additionally, the peroxidizability index (PI) was determined. No differences were observed in the proximate composition of fish muscle regardless of the diet used. Fish fed a diet supplemented with 10% of algae waste (W10) stand out for the highest content in oleic acid (C18:1 n-9), and the lowest in both linoleic (C18:2 n-6) and palmitic (C16:0) fatty acids. All fish samples showed values of health lipid indices within the limits recommend for a nutritional balanced diet. These results highlight that fish fed diets supplemented with P. canaliculata are sources of healthy lipids that might be consumed on a regular basis to prevent cardiovascular diseases.