Abstract
Turbot (Scophthalmus maximus L.) is an important industrial mariculture species in China. With the development of high-density and intensive culture, turbot always suffer from various kinds of environmental stresses, which led to the reduction of fish immunity and brought out many diseases. Therefore, it is urgent to find the green feed additives to improve the immunity of fish to avoid the disease. Chinese herbal medicine is rich in carbohydrate, lipid, vitamin and minerals, and other bioactive substances such as alkaloids, saponins, polyphenols, flavonoids, polysaccharides and terpenoids, which could stimulate the activities of complement, lysozyme and antibody reaction and promote the function of phagocytes to improve the bactericidal activity. And The herbal medicine has the advantages of non-toxic, no drug resistance, no residue and environmental friendly. “Sijunzi Decoction” is an ancient prescription in China, and mainly composed of Panax ginseng, Atractylodes macrocephala Koidz, Wolfiporia cocos and Glycyrrhiza uralensis. The main active chemical components analyzed in this Decoction are ginsenosides (from Panax ginseng), flavonoids and triterpenoids (from Glycyrrhiza uralensis). It has the pharmacological activities including improving the gastrointestinal function, invigorating spleen-reinforcing Qi and immunomodulatory activity for human. However, there is no report about the application of this Decoction in fish. Based on the components of the traditional prescription of “Sijunzi Decoction”, nine kinds of Chinese herbal medicines was chose to apply in the feed of fish in this study. To investigate the effects of different levels of a Chinese herbal medicines mixture (CHMM: decoction of Codonopsis pilosula, Atractylodes macrocephala Koidz, Wolfiporia cocos, Rehmannia glutinosa Libosc, Glycyrrhiza uralensis Fisch, Crataegus pinnatifida Bunge, Rhus chinensis Mill, Gardenia jasminoides Ellis and Zingiber officinale Roscoe) on growth performance, feed utilization, body composition and related immune indices of juvenile turbot, basal diets were supplemented with 0, 1%, 2% or 4% CHMM in the form of water decoction to feed juvenile turbot initial mean body weight was (22.01±0.01) g for 40d. The fish were fed two times every day (8: 00 and 18: 00), the light period was 14h light and 10h dark, the water dissolved oxygen was greater than 6.0 mg/L, salinity was 25‰—28‰, water temperature was 15—18℃, and ammonia nitrogen concentration was less than 0.05 mg/L. The results indicated that dietary supplementation of CHMM had no significant influence on feeding rate (P≥0.05). However, the dietary CHMM significantly influenced the growth performance and feed utilization efficiency of turbot (P<0.05), the specific growth rate (SGR) and weight gain rate (WGR) of turbot in 1% group were significantly higher than those in other groups (P<0.05), no significant difference was observed between 2% group and control group (P≥0.05). The feed coefficient (FCR) in 1% group was significantly lower than other groups (P<0.05), and there were no significant differences among other groups (P≥0.05). The supplementation of CHMM in diet significantly affected the condition factor (CF) and spleen index (SI) of turbot (P<0.05), and the highest CF and SI were observed in turbot fed 1% CHMM diet (P<0.05). Meanwhile, the supplementation of CHMM had no significant effect on the visceral index (VSI), hepatosomatic index (HSI) and body composition of turbot (P≥0.05). The contents of C3 and activities of lysozyme in plasma were significantly affected by the dietary supplementation of CHMM (P<0.05), while no significant difference was observed in the contents of plasma IgM among all treatments. The contents of plasma C3 in 1% group were significantly higher than that in control group (P<0.05), the activities of plasma LZM in 1% group were significantly higher than those in other groups (P<0.05), and no significant differences were observed among other groups (P≥0.05). In conclusion, the supplement of CHMM in diet significantly improved the growth performance, feed utilization and non-specific immunity of turbot. The optimum supplemental level of this compound Chinese herbal medicine in the feed of turbot was 1%.
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