In this study, two main probiotics (Lactobacillus plantarum andLactobacillus delbrueckiisubsp. bulgaricus) were isolated from the intestine ofTor grypus and their effects on growth performance, gut microbial flora and digestive enzymes activities (i.e., α-amylase, lipase, trypsin, chymotrypsin, and alkaline phosphatase) ofTor grypus (Karaman, 1971) were determined. Juveniles ofT. grypus (n=480, weighing 45±10 g) were randomly divided into 4 equal groups (with 3 replications) and fed on diets containing 5×107 cfu g-1 ofL. plantarum (G1),L. bulgaricus (G2),L. casei(G3) and a control diet (without probiotic) for 60 continuous days. Results showed that probiotic supplementations had generally significant effects on growth performance (p<0.05). The G2 group had the best effect on specific growth rate (SGR) and feed utilization efficiency inT. grypus. The digestive enzyme activities, on day 30 after feeding, significantly increased in G1 when compared with those in the control group (p<0.05). Significant changes in bacterial intestinal flora were observed in all probiotic groups compared with the control (p<0.05). Our results indicated that supplementation of isolated bacteria from the intestine ofT. grypus(i.e., G2) can efficiently improve growth performance, intestinal microbiota and some digestive enzyme activities in juvenileT. grypus. Therefore, it can be isolated and used as a growth enhancer just like the commercial probiotics.

Keywords:Tor grypus, Intestine lactobacilli, Growth performance, Digestive enzyme activity, Microbial flora.