Evaluation of Sargassum fusiforme and Ecklonia cava as Dietary Additives for Olive Flounder (Paralichthys olivaceus)

摘要

A 6-week feeding trial was conducted to evaluate the efficiency of hijiki (Sargassum fusiforme) and ecklonia (Ecklonia cava) as dietary supplements for juvenile olive flounder. Fish growth performance, hematology, innate immunity and disease resistance were examined. A basal experimental diet was used as a control and supplemented with 6% of either S. fusiforme or E. cava and another diet was prepared to contain 0.5% oxytetracycline (designated as Con, Hij-6, Eck-6 and OTC-0.5, respectively). The experiment was conducted in triplicate (25 fish per replicate) and the fish (initial body weight, 18.3±0.04 g) were fed one of the test diets at a rate of 3% body weight twice daily. Significantly higher (P<0.05) antioxidant capacity and polyphenolic compounds concentration were detected in hijiki and ecklonia supplemented diets. At the end of the feeding trial, fish growth performance and feed utilization were not significantly affected by dietary treatments. Significantly higher (P<0.05) hemoglobin level and respiratory burst activity were found in fish fed Hij-6 diet. The fish fed Hij-6 and Eck-6 diets exhibited higher resistance against Edwardsiella tarda challenge compared to those fed Con and OTC-0.5 diets. The findings in this study may show that hijiki and ecklonia can be used as environment friendly substitutes for antibiotics in diets for olive flounder.