EFFECT OF DIETARY INCLUSION OF THE VARIOUS SOURCES OF ADDITIVES ON PERFORMANCE AND CHALLENGE TEST OF JUVENILE ROCKFISH, (Sebastes Schlegeli)

Dietary inclusion of the various sources of additives on growth, body composition and challenge test of juvenile rockfish (Sebastes schlegeli) was determined. One thousand six hundred and eighty fish averaging 3.0g were randomly distributed into 24, 200 L flow-through tanks. Eight experimental diets were prepared; the control diet (Con)  with no additive, ginger (GG), cheongkukjang (CJ), blueberry (BB), persimmon (PM), tomato (TT), broccoli (BC) and yacon (YC). One percent of each additive was included in the each experimental diet at the expense of wheat flour except for the Con diet. At the end of the 7-week feeding trial, fish was used for the Streptococcus parauberis challenge and water was not exchanged throughout the challenge test.

Weight gain and specific growth rate (SGR) of fish fed the YC diet was significantly higher than that of fish fed the all other diets, followed by the GG, BB and Con diets. Feed conversion ratio (FCR) and protein efficiency ratio (PER) of fish fed the TT and YC diets were significantly higher than those of fish fed the all other diets. FCR and PER of fish fed the Con and GG diets were significantly higher than those of fish fed the CJ, BB, PM and BC diets. Accumulative mortality of rock fish fed the Con diet was significantly higher than that of fish fed the all other diets since 36-hr after infection throughout the 10 day observation (Fig. 1). All dietary additives used in this study were effective to lower mortality of rockfish at occurrence of S. parauberis. At 10 day, the lowest cumulative mortality was observed in fish fed the GG diet, followed by the BB, YC, CJ, BC, PM, TT and Con diets in order. This indicated that GG, BB and YC would be the good dietary additive to lower mortality of rock fish at occurrence of S. parauberis. In Conclusion, YC was the best dietary additive to improve weight gain and SGR of rockfish. In addition, YC and TT was the most effective to obtain improved FCR and PER of fish. However, dietary inclusion of GG, BB and YC were the most effective to lower mortality of rockfish at infection of S. parauberis.