Towards Sustainable Aquafeeds: Valorization of Codium sp. and Osmundea sp. as Functional Ingredients to Enhance Nutrient and Bioactive Compounds in European Seabass

Abstract

This study aimed to valorize Codium sp. and Osmundea sp. as functional ingredients for European seabass diets. For this purpose, triplicate groups of 25 fish (20.6 g) were fed, during 8 weeks, one of seven diets: the control (CTR), 5% of Codium and Osmundea ground (diets CO and OS, respectively), 5% of Codium and Osmundea ground and autoclaved (diets COA and OSA, respectively), and 0.5% of Codium and Osmundea polysaccharide extracts (diets COP and OSP, respectively). The same diets were used for a digestibility trial. Fish fed the CO diet presented lower growth and an apparent digestibility coefficient (ADC) for dry matter and protein compared to fish fed the CTR and OS diets. Diet COA counteracted these negative effects. No differences were observed in feed intake, feed efficiency, and lipid ADC. Antioxidant enzyme activities and distal intestine histomorphology, an indicator of gut health, were not affected. The expression of interleukin-1β and interleukin-6 increased in fish fed the COP diet. In conclusion, the processing methods counteracted the negative effects of raw Codium, enhancing its value as a dietary ingredient, while its polysaccharides showed immunomodulatory potential that could be valuable during stress or disease periods. These findings support the valorization of these algae for aquafeeds, with Osmundea being safely included at 5% without processing.

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