Effects of Probiotic-Fermented Chinese Herb on Immune Response and Growth Performance in Common Carp (Cyprinus carpio)

This study investigated the effects of fermented Chinese herb (FCH) on the growth indices, leukocyte activity, and biochemical indices of carp (Cyprinus carpio). Astragalus membranaceus (AM), Pericarpium Citri Reticulatae (PCR), and Glycyrrhizae Radix et Rhizoma (GRR) as feed additives enhance immune function, promote growth, and exert anti-inflammatory effects, respectively. Therefore, this study investigated the effects of co-fermented blends of these three herbs on growth performance and related parameters in common carp. By adding 2%, 5%, and 10% of the FCH to co-incubate with carp leukocytes, the results show that all three experimental treatments could enhance the respiratory burst activity and phagocytic activity of carp leukocytes. After 28 days of feeding with basal feed supplemented with 2%, 5%, and 10% (w/v) of the FCH, the weight gain rate and specific growth rate of carp were significantly higher than those of the control treatment without additives (ANOVA, p < 0.05), with the 5% treatment showing the highest. The activities of intestinal digestive enzymes were significantly increased (ANOVA, p < 0.05). On the 21st day, the activities of amylase (AMS), lipase (LPS), and chymotrypsin were increased compared to the control treatment. The 5% and 10% treatments showed significantly higher intestinal digestive enzyme activities compared to the 2% treatment. The serum superoxide dismutase (SOD) levels in both the control and experimental treatments initially increased and then decreased, with all three experimental treatments having higher levels than the control treatment. The activities of liver glutamic-oxaloacetic transaminase (GOT) and glutamic-pyruvic transaminase (GPT) in the experimental treatments showed no significant changes compared to the control treatment (ANOVA, p > 0.05). However, the serum GPT activity in the 5% treatment was significantly lower than that of the control treatment (ANOVA, p < 0.05), while no significant differences were observed in the other treatments. The results indicate that adding 2~10% of FCH to carp feed can improve intestinal digestion, enhance phagocytic activity and the body’s antioxidant defense capabilities, and effectively promote the growth of carp. It can significantly improve farming efficiency and economic benefits, reduce dependence on chemical drugs, and lower environmental pollution, showing good application prospects in production.