Abstract
Fermented traditional Chinese medicines (TCMs) have been identified as a low-cost and promising feed additive to to alleviate weaning stress in young livestock and poultry effectively. This study investigated the impact of probiotic fermentation on the metabolite content of BanQi (Radix Isatidis and Astragalus membranaceus) extract while also examined the effects of both fermented-BanQi (FBQ) and unfermented-BanQi (UBQ) on growth performance, serum biochemistry, intestinal villi, and gut microbiota in weaned lambs. This study demonstrated that compared with UBQ, FBQ contained significantly higher levels of free amino acids (e.g., phenylalanine and isoleucine), short peptides (e.g., Val-Leu-Pro-Val-Pro-Gln and Gly-Leu), and the active ingredients (e.g., vindesine and reserpine) (P < 0.05). The addition of FBQ to the diet significantly increased the final body weight and average daily gain of weaned lambs (P < 0.05). In addition, FBQ significantly increased the total protein level in the serum and the villus length of the jejunum and ileum in lambs, while significantly reduced the levels of aspartate aminotransferase (AST) and urea (P < 0.05). Sequencing of the intestinal flora showed that FBQ improved the diversity of intestinal flora and promoted the enrichment of beneficial bacteria in the lamb intestine, such as Mogibacterium and Butyrivibrio, compared to NC or UBQ groups (P < 0.05). Fermentation with Bacillus subtilis can enhance the content of free amino acids, peptides, and active ingredients in BanQi extract, making it an effective method to improve the efficacy of traditional Chinese medicine. Adding FBQ to the diet can improve the growth performance of weaned lambs, and its mechanism may be related to increasing the height of intestinal villi and increasing the diversity of intestinal flora.