Combined effects of emodin and Clostridium butyricum on growth and nons-pecific immunity of giant freshwater prawns, Macrobrachium rosenbergii

This study was conducted to evaluate the individual and combined effects of emodin and Clostridium butyricum on growth and non-specific immunity of giant freshwater prawn (Macrobrachium rosenbergii) for eight weeks with the initial body weight of 0.19 +/- 0.5 g. Nine trial diets were prepared to contain three emodin levels (0, 25 and 50 mg/kg) and three C. butyricum levels (0, 250 and 500 mg/kg, 2 x 10(7) CFU/g) following a 3 x 3 factorial design. The diets were named as 0/0, 250/0, 500/0, 0/25, 250/25, 500/25, 0/50, 250/50 and 500/50 (C. butyricum/emodin), respectively. The results showed an interactive effect on the weight gain (WG) and feed conversion ratio were observed in prawns fed a diet containing 250 mg/kg C. butyricum and 50 mg/kg emodin, respectively. Besides, WG and specific growth rate (SGR) of prawns fed 250 mg/kg C. butyricum were both significantly (P<.05) higher than that of the other treatments regarding C. butyricum. Higher values of inducible nitric oxide synthase (iNOS), nitric oxide (NO), and respiratory burst were observed with the increasing level of dietary emodin. Aspartate aminotransferase (AST) activities and total protein (TP) contents improved directly with the increasing levels of C. butyricum (P<.05). Furthermore, the content of interferon-gamma (INF-gamma), IL-1, TNF-alpha, and IL-6 were augmented by the dietary emodin and the interaction of C. butyricum and emodin was found in the contents of IL-1 and TNF-alpha. The mRNA expression of relish was affected significantly by emodin and the interaction of C. butyricum and emodin (P<.05). The mRNA expression of peroxiredoxin-5 was affected significantly by individual and interactional effects of emodin and C. butyricum (P<.001). The present study indicated that the individual or combined effects of C. butyricum and emodin could significantly improve the growth performance and improve the antioxidative status of M. rosenbergii. The optimum combination of these components was 250 mg/kg C. butyricum (2 x 10(7) CFU/g) and 50 mg/kg emodin, respectively.