Effect of Organic Plant Ingredients on the Growth Performance of European Sea Bass (Dicentrarchus labrax): Nutritional Efficiency, Fillet Nutritional Indexes, Purchase Intention, and Economic Analysis

The objective of the present study was to ascertain the effect of diverse organic feeds (25ECO, 30ECO, and 35ECO) containing varying levels of fishmeal (25%, 30%, and 35%) on the growth and fillet quality of juvenile sea bass. The ECO diets were composed of a blend of organic vegetable proteins. The control diet contained 30% fishmeal without any organic ingredients. The experimental period spanned 196 days, during which the fish were fed twice daily, with an initial mean weight of 40 g. The results indicated that reducing fishmeal to 25% in the 25ECO diet negatively affected growth and increased feed consumption. The 30ECO diet, which contains 30% fishmeal, exhibited no adverse effects; however, its biometric outcomes diverged from those of the control diet. The 25ECO diet demonstrated superior Met retention levels, and certain free amino acids that enhance flavour (SER, ALA, ASP, and GLU) exhibited higher concentrations in fillets from fish fed ECO diets (35ECO and 30ECO). No substantial disparities were observed in the fatty acid profile or fillet nutritional indexes, which were deemed to be satisfactory and conducive to good health. From an economic perspective, the 30 ECO diet was deemed optimal and exhibited the greatest inclination towards purchase.