Under the principles of the circular economy, replacing traditional and imported ingredients with available agro-industrial by-products is essential to promote aquaculture sustainability. This study evaluates the feasibility of incorporating alkaline pre-treated Gelidium macroalgae by-product (GBP) in European seabass (Dicentrarchus labrax) diets, alone or in combination with an exogenous carbohydrase complex (Natugrain®). From a control diet (Diet CTRL: CP:44%; EE 16%), three isonitrogenous and isolipidic experimental diets were formulated including 15%GBP (Diet G15), 15%GBP with 1%Natugrain® (Diet G15Nat1) and 15%GBP with 2%Natugrain® (Diet G15Nat2), replacing a mixture of soybean and wheat meals. A total of 360 seabass juveniles (12.7±0.2 g) were randomly distributed into 12 RAS tanks (3 tanks per dietary treatment; 30 fish per tank) and fed twice a day until satiation for 62 days. Final body weight (33.4 g, on average), specific growth rate (1.58% day−1), and viscerosomatic index (2.7%) were similar among experimental diets and diet CTRL (p>0.05), whereas feed efficiency and protein efficiency ratio were lower (−19% and −18%, respectively) in fish fed experimental diets compared to those fed diet CTRL (p<0.01). Whole-fish carcass composition was not affected by GBP inclusion, alone or enzyme-supplemented (p>0.05). Overall, 15% GBP inclusion did not impair growth performance but reduced feed utilisation, whereas the supplementation of Natugrain® did not enhance growth performance or feed efficiency compared to the addition of GBP alone. Future research should evaluate ingredient digestibility, assess the functional properties of GBP, and optimise processing and feeding strategies, to improve nutrient bioavailability and valorise GBP as a novel and sustainable ingredient for aquafeed, increasing the circularity of aquaculture.
Incorporating agar by-products in European seabass diets: A circular economy approach to sustainable aquaculture
Fanizza C.
;Trocino A.;
2025
Abstract
Under the principles of the circular economy, replacing traditional and imported ingredients with available agro-industrial by-products is essential to promote aquaculture sustainability. This study evaluates the feasibility of incorporating alkaline pre-treated Gelidium macroalgae by-product (GBP) in European seabass (Dicentrarchus labrax) diets, alone or in combination with an exogenous carbohydrase complex (Natugrain®). From a control diet (Diet CTRL: CP:44%; EE 16%), three isonitrogenous and isolipidic experimental diets were formulated including 15%GBP (Diet G15), 15%GBP with 1%Natugrain® (Diet G15Nat1) and 15%GBP with 2%Natugrain® (Diet G15Nat2), replacing a mixture of soybean and wheat meals. A total of 360 seabass juveniles (12.7±0.2 g) were randomly distributed into 12 RAS tanks (3 tanks per dietary treatment; 30 fish per tank) and fed twice a day until satiation for 62 days. Final body weight (33.4 g, on average), specific growth rate (1.58% day−1), and viscerosomatic index (2.7%) were similar among experimental diets and diet CTRL (p>0.05), whereas feed efficiency and protein efficiency ratio were lower (−19% and −18%, respectively) in fish fed experimental diets compared to those fed diet CTRL (p<0.01). Whole-fish carcass composition was not affected by GBP inclusion, alone or enzyme-supplemented (p>0.05). Overall, 15% GBP inclusion did not impair growth performance but reduced feed utilisation, whereas the supplementation of Natugrain® did not enhance growth performance or feed efficiency compared to the addition of GBP alone. Future research should evaluate ingredient digestibility, assess the functional properties of GBP, and optimise processing and feeding strategies, to improve nutrient bioavailability and valorise GBP as a novel and sustainable ingredient for aquafeed, increasing the circularity of aquaculture.
Pubblicazioni consigliate
I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
