Process optimization of compound fermented traditional Chinese medicine and its feeding effect on dairy cows

This study evaluated the efficacy of a compound fermented traditional Chinese medicine (TCM) preparation in dairy cows. Five TCMs and three probiotics were selected from 25 candidate herbs and six probiotics based on in vitro antibacterial activity against Staphylococcus aureus and Escherichia coli using agar well diffusion and paper disc diffusion methods. The five TCMs were formulated according to the "Jun-Chen-Zuo-Shi" principle, and the optimal solid-state fermentation process was identified through single-factor and orthogonal experiments. The results showed that the optimal conditions included a Bacillus subtilis: Bacillus coagulans: Lactobacillus plantarum ratio of 1:3:1, a moisture content of 32%, an inoculation rate of 10%, a temperature of 31 °C, and a fermentation duration of 5 d. HPLC was used to examine changes in bioactive compound levels before and after fermentation. Fermentation significantly increased the concentrations of Resveratrol, Salvianolic acid B, and Quercetin, whereas the Polydatin content decreased. To determine in vivo effects, the fermented TCM was fed to dairy cows, and the indices of production performance, milk quality, serum biochemical levels, immune function, antioxidant capacity, and hormone levels were evaluated. Additionally, the changes in intestinal flora were analyzed by sequencing rectal contents using 16 S rRNA. The results showed that fermented TCM could improve the production performance of dairy cows and milk quality, enhance humoral immunity, strengthen antioxidant capacity, induce modest shifts in gut microbiota composition, and regulate metabolism. This study provides reliable experimental evidence supporting the development and application of compound fermented TCM as a functional feed additive in dairy production.