Effect of Mussel Meal Feed Supplement on Growth, Health Status, Proximate Composition and Fatty Acid Profile of Gilthead Seabream (Sparus aurata)

To evaluate the effects of mussel meal, as a sustainable ingredient for fish feed, on the growth, health status, proximate composition, and fatty acid profile of gilthead seabream, mussel meal was included in commercial feed formulations. Sunflower oil (2%) was used as a binding agent. Four groups of gilthead seabream were fed either with control feed (commercial feed, commercial feed and sunflower oil) or mussel-meal-supplemented formulations (commercial feed, sunflower oil, and 2.5 or 5% mussel meal) for six weeks. In this experiment, a total of 180 specimens of gilthead seabream juveniles were included. The initial weight and length of the gilthead seabream specimens were, on average, 13.04 g and 9.57 cm, respectively. The average temperature of the seawater ranged between 25 and 26 °C during the experiment. The results of this study indicated a higher relative weight gain and a slightly lower feed conversion ratio in the control group fed with commercial feed, probably because of macronutrient imbalances introduced by the addition of mussel meal and sunflower oil. The groups fed with mussel-supplemented diets had a slightly lower crude protein content compared to the group fed with a commercial diet. The addition of sunflower oil and mussel meal decreased the saturated fatty acid content while increasing the monounsaturated and polyunsaturated fatty acid content compared to the control group. However, the high content of DHA and EPA in the mussel meal resulted in a proportional increase of these fatty acids in the muscle tissue of gilthead seabream, although the overall effect was not statistically significant. The findings of this study suggest that mussel meal is a promising source of protein and lipids for sustainable fish feed production, but under the experimental setup, mussel meal did not act as an attractant for increasing fish feed intake during the summer conditions.