Effects of dietary Chinese herbal medicines mixture on feeding attraction activity, growth performance, nonspecific immunity and digestive enzyme activity of Japanese seabass (Lateolabrax japonicus)

The purpose of this study was to evaluate the effects of Chinese herbal medicines mixture (CHMM: consisted of asafoetida Ferula sinkiangensis K. M. Shen, Medicago falcata L.and Allium sativum) on feeding attraction activity (FAA), growth performance, nonspecific immunity and digestive enzyme activity of juvenile Japanese seabass (Lateolabrax japonicus). Six diets containing 0, 5, 10, 15, 20 and 25 g/kg CHMM were designed for the luring and feeding experiment. A clear attractive trend of the CHMM on Japanese seabass was found after a 5-day luring trial. The 28-day feeding experimental results indicated that dietary CHMM significantly influenced weight gain (WG) and specific growth rate (SGR) of fish (P < 0.05), with the highest WG and SGR observed in fish fed 20 g/kg CHMM diet. The feed conversion ratio (FCR) of each treatment group was significantly reduced by the CHMM. The body crude lipid content was significantly increased except for the 15 g/kg group (P < 0.05). The supplementation of CHMM could significantly increase the activity of lysozyme (LZM) and total superoxide dismutase (T-SOD) in serum with the highest values observed in the 20 mg/kg group while the content of total protein (TP) was increased significantly in the fish fed the diet with 10 15 g/kg CHMM (P < 0.05). Digestive enzymes including lipase (LPS) and trypsin activities were obviously affected by the CHMM and reached the highest among all groups at 20 g/kg diet. Regression analyse of the FAA, FCR, WG, SGR, TP, LZM, T-SOD, LPS and trypsin were performed, showing the optimal additional amount was 12.75, 15.09, 20.14, 20.00, 16.13, 18.31, 17.33, 21.38 and 21.17 g/kg, respectively. Comprehensive consideration of the current experimental results and the regression analyses, we suggested the additive suitable dosage of the CHMM was 20 g/kg diet