Growth performance, non-specific immunity, intestinal histology and disease resistance of Litopenaeus vannamei fed on a diet supplemented with live cells of Clostridium butyricum

This study conducted a 42-day feeding trial and a subsequent 14-day challenge test to Vibrio parahaemolyticus to determine the effects of Clostridium butyricum CBG01 on the growth, immune responses, intestinal histology and disease resistance of Litopenaeus vannamei (initial weight 1.60 +/- 0.02 g). Shrimp were fed with seven experimental diets containing different doses of C. butyricum with 0, 1 x 10(7), 1 x 10(8), 1 x 10(9), 1 x 10(10), 1 x 10(11) and 1 x 10(12) cfu/kg (the control, LA, LB, LC, LD, LE and LF, respectively). The result indicated that specific growth rate and weight gain of shrimp in LE and LF group were significantly improved while feed conversion ratio for all treatments were significantly reduced as compared to the control (P < .05). The intestinal villus height of shrimp in all treatments was significantly higher than the control (P < .05), and the intestinal wall thickness in treatments except LE were higher than the control (P < .05). The activities of alkaline phosphatase (AKP), acid phosphatase (ACP), lysozyme (LZM) and total nitric oxide synthase (TNOS) in the serum of shrimp for LE and LF group were all significantly enhanced (P < .05). However, no significant difference in the superoxide dismutase (SOD) activity was found among the control, LA, LB, LC, LD and LF. The respiratory burst activity of hemolymph for the shrimp in LB, LC, LE and LF significantly higher than the control (P < .05). The expression level of Toll, Imd and Relish gene in lymphoid organ of shrimp in LC, LD, LE and LF were higher significantly those in the control (P < .05). After injection of inactivated V. parahaemolyticus, Relish gene expression level in LE and LF was significantly up-regulated at 1 and 2 h (P < .05). In the challenge test to V. parahaemolyticus, the cumulative mortality of shrimp in LD, LE and LF were significantly lower than the control (P < .05). These results suggested that 1011 and 1012 cfu/kg C. butyricum supplemented into feed could significantly improve the growth performance, immunity capacity and resistance against V. parahaemolyticus of L. vannamei, also have a positive effect on the intestinal morphological structure.