Evaluation of the seaweeds Chondrus crispus and Ulva lactuca as functional ingredients in gilthead seabream (Sparus aurata)

The effect of a dietary incorporation of the seaweeds Ulva lactuca and Chondrus crispus as functional ingredients was evaluated in gilthead seabream ( Sparus aurata ) juvenile growth, feed efficiency, muscle lipid composition, intermediary metabolism, oxidative status and gut histomorphology. Fish (15 g initial body weight) were fed with isoproteic (46%) and isolipidic (18%) diets with fish meal (FM) and plant feedstuffs (PF) (27:73 protein from FM:PF) as main protein sources (control diet). Three other diets were formulated similar to the control but including 5% U. lactuca , 5% C. crispus or 2.5% of both algae (diets Ulva , Chondrus and Mix, respectively). Dietary incorporation of Ulva did not affect growth performance ( P > 0.05) while it leads to higher muscle ΣSFA (saturated fatty acids); and liver lipid peroxidation (LPO). Moreover, lower muscle ΣPUFA (polyunsaturated fatty acids) and plasma glucose was observed. Dietary incorporation of Chondrus leads to lower growth; whole-body dry matter and lipid content; muscle ΣPUFA and ω3 fatty acids; and plasma glucose. In addition, higher muscle ΣMUFA (monounsaturated fatty acids); and liver LPO was observed. Dietary incorporation of both algae (Mix) led to lower growth; whole-body lipid content; muscle ΣPUFA and ω3 fatty acids; plasma glucose; and hepatic PK (pyruvate kinase) and HOAD (3-hydroxyacyl-CoA dehydrogenase). Furthermore, it leads to higher muscle ΣSFA and ΣMUFA; and liver LPO. Overall, no beneficial effects of including the tested seaweeds in the diets was observed, while oxidative status was negatively affected in all dietary treatments.