Marine hydrolysates as functional nutritional supplements to promote European seabass (Dicentrarchus labrax) robustness addressing the European zero-waste strategy

• Autor(a) principal: Rodrigues, João
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.1/20421
• topic: Subprodutos de pescado; Hidrolisados; Péptidos bioativos; Dieta funcional; Dieta sustentável; Economia circular

Traditionally, fishmeal is the standard dietary protein for aquaculture-produced species, but environmental and economic concerns drive the shift to sustainable-oriented practices. Plant-based proteins are a more sustainable alternative to fishmeal. However, they have drawbacks such as antinutritional factors that affect fish growth, intestinal health, and immunity. Recent research indicates that low dietary inclusion rates of marine protein hydrolysates enhance the nutritional quality of high-vegetable protein diets, positively impacting fish growth and robustness. Thus, in this study, the effects of supplementing a highly vegetable-based commercial diet with 3% blue shark skin hydrolysate on the growth, stress response, and disease resistance of juvenile European seabass were assessed. The fish growth parameters were mostly unaffected when comparing the experimental (SHARK) to the commercial diet (CTRL), except for a higher protein efficiency ratio (PER) in the CTRL treatment. However, fish showed good acceptance, metabolization, and utilization of the SHARK diet. The whole-body composition showed a higher ash content in the SHARK treatment, likely due to the hydrolysate mineral profile. In response to a stress challenge, fish fed both diets presented a typical increase in glucose, lactate, and cortisol levels. Interestingly, fish fed the SHARK diet showed significantly lower cortisol levels, suggesting better energy utilization. No negative significant impact on animal metabolism was observed. Regarding the immune markers, peroxidase levels were higher in the CTRL treatment after the stress challenge, but other immune indicators remained unaffected by the diet. During the infectious challenge with Photobacterium damselae subsp. piscicida, both treatments showed similar low cumulative mortality rates. This study demonstrates that incorporating low levels of blue shark skin hydrolysate into low fishmeal diets does not impact the growth and robustness of juvenile European seabass. This suggests that the hydrolysate is a safe and beneficial ingredient for aquafeeds targeted at this fish species.