Partial replacement of corn and soybean meal with yeast culture improves growth performance and intestinal health and is associated with cecal microbiota modulation in broilers.

Yeast culture (YC) has demonstrated beneficial effects on animal growth and intestinal health as a functional additive; however, its potential as a partial substitute for conventional corn and soybean meal (SBM) in broiler diets remains unclear. Therefore, this study aimed to evaluate the effects of partially replacing corn and soybean meal with YC on growth performance, antioxidant capacity, intestinal health, and gut microbiota in broilers. A total of 900 healthy one-day-old Cobb broilers were randomly divided into three treatment groups with 15 replicates of 20 birds/pen. The broilers were fed either a basal diet (CON), a basal diet with 2% YC replacing 1% corn and 1% SBM (2% YC), or a basal diet with 3% YC replacing 1.5% corn and 1.5% SBM (3% YC) for 35 days. The results showed that, compared with the CON, 3% YC treatment significantly increased (p < 0.05) the average daily gain and average daily feed intake, as well as reduced (p < 0.05) the feed-to-gain ratio during the various experimental periods. Meanwhile, 3% YC increased (p < 0.05) the activities of SOD and GPX in serum, villus height, and the expression of ZO-1, Claudin-2, and IL-10 proteins in jejunum. Further cecal microbiota analysis showed that 3% YC enriched (p < 0.05) the abundances of Butyricicoccus, and Kineothrix genera. Furthermore, 3% YC treatment increased (p < 0.05) the cecal butyric acid concentration and also showed a trend toward increased (p = 0.07) butyric acid production in an in vitro fermentation trial. In conclusion, the improvement in broiler growth performance with 3% YC substitution may be associated with increased antioxidant capacity, jejunal morphology and barrier function, and modulation of cecal microbiota. These findings suggest that 3% YC could serve as a promising partial substitute for corn and SBM in broiler diets.