Effects of dietary <i>Clostridium butyricum</i> on growth performance, non-specific immunity, intestinal microbiota and disease resistance of <i>Scylla paramamosain</i>

This investigation examined how Clostridium butyricum influences the growth, innate immune reaction, intestinal microbiota, and disease resistance of Scylla paramamosain . Different concentrations of C. butyricum were sprayed on the feed: 0 (CC), 3.6×10 4 CFU/g (CB1), 3.6×10 5 CFU/g (CB2), 3.6×10 6 CFU/g (CB3), and 3.6×10 7 CFU/g (CB4) over 42 days. The findings indicated that the final weight and specific growth rates of S. paramamosain in the CB2 and CB3 treatment groups were significantly greater compared to the other groups ( P &lt;0.05). Compared to the control group, the activities of alkaline phosphatase (AKP), superoxide dismutase (SOD), total antioxidant capacity (T-AOC), and intestinal lipase (LPS) were all elevated, with significant improvements noted particularly in the CB3 group ( P &lt; 0.05). Furthermore, the relative expression levels of the IL8 and TNF-α genes in the CB2 and CB3 groups and the GPx3 and SpPO genes in CB3 and CB4 groups were markedly elevated compared to the other groups ( P &lt; 0.05). Incorporating 3.6×10 6 CFU/g of C. butyricum into the diet improved the variety of the gut flora in S. paramamosain . Functional analysis conducted through KEGG Pathway Level 2 indicated that the experimental group had more metabolism-related pathways than the control group, with the CB3 group displaying the highest levels. In conclusion, including an appropriate level of C. butyricum within the dietary composition can foster the growth of S. paramamosain , enhance the diversity of gut microbiota, and improve immune function; the optimal concentration identified was 10 6 CFU/g in the feed.