Effects of <i>Clostridium butyricum</i> on Growth, Immunity, and Intestinal Microbiota of <i>Penaeus monodon</i>

This study aimed to investigate the effects of Clostridium butyricum and its metabolites on the growth, antioxidant capacity, and intestinal microbiota of a selected population of Penaeus monodon . A total of 360 shrimp with similar vitality and size, having an initial body mass of (2.33±0.05) g, were selected and randomly divided into four groups, with three replicates per group and 30 shrimp per replicate. The groups were designated as the control group (CG, no additive in feed), the yeast extract group (YYG, feed supplemented with C. butyricum yeast extract), the supernatant group (SQG, feed supplemented with the supernatant of C. butyricum ), and the juice-sediment group (JNG, feed supplemented with the bottom sediment of C. butyricum ). Following 31 days feeding trial, the results showed that compared with the CG, the weight gain (WG), survival rate (SR), and specific growth rate (SGR) of YYG, SQG, and JNG increased, with YYG being significantly higher than CG ( P &lt;0.05), while JNG and SQG did not show significant differences compared to CG ( P &gt;0.05). Protease and lipase activities were significantly enhanced in YYG ( P &lt;0.05), alkaline phosphatase (AKP) activity was significantly higher in YYG and JNG than in CG ( P &lt;0.05), while there was no significant difference between SQG and CG ( P &gt;0.05). Acid phosphatase (ACP) activity was significantly higher in YYG and SQG compared to CG ( P &lt;0.05), with no significant difference between JNG and CG ( P &gt;0.05). Intestinal microbiota sequencing revealed that Proteobacteria was the most abundant phylum in all experimental groups, accounting for 71%, 69%, 73%, and 75% respectively. At the gene expression level, compared with CG, YYG showed significantly higher relative expression levels of immune-related genes such as PO, Toll, IMD, and Relish, as well as antioxidant-related genes such as CAT, GSH, and hsp70 in the hepatopancreas of P. monodon ( P &lt;0.05). Under the conditions of this experiment, supplementing feed with C. butyricum yeast extract achieved the best probiotic effect in P. monodon farming.