Effects of Dietary Kugija Lycium chinense Supplementation on Juvenile Korean Rockfish Sebastes schlegeli

A 8-week feeding trial was conducted to investigate the effects of dietary supplementation of Kugija (Lycium chinense) on the growth and immunological response in juvenile Korean rockfish (Sebastes schlegeli). Six experimental diets were supplemented with Kugija at 0, 0.1, 0.5 1.0, 3.0 and 5.0% ($K_0,\;K_{0.1},\;Ko_{0.5},\;K_{1.0},\;K_{3.0},\;K_{5.0}$) on a dry-matter basis. After 2 weeks, triplicate groups of 30 fish initially averaging 3.36$\pm$0.2 g (mean$\pm$SD) were randomly distributed into the aquarium and were fed one of the experimental diets for 8 weeks. By the end of the 8-week feeding trial, fish fed the $K_{0.5}$ and $K_{1.0}$ diets exhibited a higher weight gain and specific growth rate than fish fed $K_0$ and $K_{0.1}$ diets (P<0.05). Feed efficiency of fish fed the $K_{0.5}$ diet showed significant higher value than that of fish fed the $K_0$, $K_{3.0}$ and $K_{5.0}$ diets (P<0.05). Hepatosomatic index of fish fed the $K_{0.5}$ diet was significantly higher than that of fish fed the $K_{0.1}$ and $K_{5.0}$ diets (P<0.05). Hematocrit of fish fed the $K_{0.5},\;K_{1.0}$ and $K_{5.0}$ diets was significantly higher than that of fish fed the $K_0$ diet (P<0.05). Glutamic oxaloacetic transaminase of fish fed the $K_{0.5},\;K_{1.0},\;K_{3.0}$ and $K_{5.0}$ diets was significantly lower than in fish fed the other diets (P<0.05). Glutamic pyruvic transaminase activity of fish fed the $K_{3.0}$ diet was significantly lower than those of fish fed the $K_0$ and $K_{0.1}$ diets (P<0.05). However, there was no significant difference in the activity of the transaminase in fish fed the $K_{0.5}\;K_{1.0},\;K_{3.0}$ and $K_{5.0}$ diets. Lysozyme activity of fish fed the $K_{0.5}$ and $K_{1.0}$ diets was significantly higher than that in fish fed the $K_0$ and $K_{0.1}$ diets (P<0.05). Respiratory burst activity of fish fed the $K_{3.0}$ diet was significantly higher than those of fish fed the $K_0$ and $K_{0.1}$ diets (P<0.05). However, there was no significant difference in respiratory burst activity of fish fed the $K_{0.5}\;K_{1.0},\;K_{3.0}$ and $K_{5.0}$ diets. Fish fed Kugija showed lower early mortality than fish fed a Kugija-free diet upon challenge with Vibrio ordalii. The results suggest that feeding of Kugija (Lycium chinense) enhances growth, non-specific immunity and disease resistance in juvenile Korean rockfish.

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