Effects of the Clostridium butyricum on growth performance, antioxidant capacity, immunity and disease resistance of Litopenaeus Vannamei fed with cottonseed protein concentrate (CPC) replacement of fishmeal in diet

Clostridium butyricum (CB) is a gram-positive bacterium that secretes short-chain fatty acids such as butyric acid and so on. An 8-week feeding trial was conducted to investigate the effects of CB on the growth performance, antioxidant capacity, immunity and resistance to Vibrio parahaemolyticus in Litopenaeus Vannamei fed with cottonseed protein concentrate (CPC) replacement of fishmeal. Six iso-nitrogenous (40%) and iso-lipidic (6%) diets were formulated including a positive control group (PC, 25% fishmeal), a negative control group (NC, CPC replaced 30% of fishmeal protein), and 0.03% (C1, 3 x 10(8) CFU/kg), 0.12% (C2, 1.2 x 10(9) CFU/kg), 0.48% (C3, 4.8 x 10(9) CFU/kg) and 1.92% (C4, 1.92 x 10(10) CFU/kg) CB were supplemented on the negative control group (NC). After the feeding trial, the remaining shrimp in each treatment group were subjected to a challenge experiment with Vibrio parahaemolyticus. The results indicated that weight gain rate (WGR), specific growth rate (SGR) in C4 group were significantly lower than those in PC and C2 groups (P < 0.05); the feed conversion ratio (FCR) was significantly higher than that of PC and C2 groups (P < 0.05). There was no significant difference in survival rate (SR) among all groups (P > 0.05). Compared to the PC and NC groups, the total superoxide capacity, superoxide dismutase and lysozyme were significantly higher in the C4 group (P < 0.05); the glutathione peroxidase, acid phosphatase and alkaline phosphatase were significantly higher in the C3 group (P < 0.05); and the malondialdehyde was significantly lower in the C4 group (P < 0.05). The relative mRNA expressions of Toll receptor (TLR), innate immune deficiency gene (IMD), penaiedin3a (Pen3) were significantly down-regulated in the NC group than those in the PC group (P < 0.05). In addition, the relative mRNA expressions of TLR, IMD and Pen3 were significantly up-regulated in all groups supplemented with CB than those in the NC group (P < 0.05). Moreover, the cumulative mortality rate in the NC group was not significantly different from the PC group (P > 0.05) and was significantly higher than those in the C3 and C4 groups (P < 0.05). In conclusion, the CB supplementation on the basis of CPC replacement of 30% fishmeal protein enhanced significantly the antioxidant capacity, immunity and disease resistance of shrimp and improved its growth performance. Therefore, considering the factors of the growth, immunity and disease resistance, the CB supplementation of 0.12%-0.48% (1.2 x 10(9) CFU/kg-4.8 x 10(9) CFU/kg) was recommended in the diet of L. vannamei based on the results of this experiment.

Automated summary

In this study, an 8-week feeding trial and challenge experiment were conducted to investigate the effects of different concentrations of CB on the growth performance, antioxidant capacity, immunity, and resistance to Vibrio parahaemolyticus in Litopenaeus vannamei. The results showed that the supplementation of CB at appropriate levels significantly enhanced the antioxidant capacity, immunity, and disease resistance of shrimp, while improving their growth performance.