Dietary Oregano aqueous extract improves intestinal health of broilers through modulating gut microbial populations

Abstract Background: Intestinal health plays an important role in broiler chicken production. Oregano aqueous extract (OAE) effectively exerts anti-inflammatory and antibacterial effects. However, the protective effects of OAE on gut health in broilers and the underlying mechanism remain unclear. This study aimed to investigate the potential effects of OAE on production performance, the intestinal microbiome and gut health, and to verify the effect of intestinal microbe on gut health. Results: Dietary 700 mg/kg OAE supplementation resulted in an increase (P < 0.05) in body weight and a decrease (P < 0.05) in feed conversion ratio than the control at D42 of the trial. Compared to the control, OAE addition resulted in lower (P < 0.05) jejunal crypt depth and the relative mRNA expression of IL-4 and IL-10 at D42. Dietary OAE increased (P < 0.05) the abundance of Firmicutes and Lactobacillus in the cecum, and affected the content of short-chain fatty acids. In addition, the results of microorganisms affected by OAE in vitro were consistent with those in vivo. The relative mRNA expression of IL-4 was significantly increased (P < 0.05) by feeding oregano fermentation microorganisms at D42. And the secretion of SIgA was significantly increased (P < 0.05) in the ileum in S group.Conclusions: Dietary OAE addition could increase the abundance of intestinal Lactobacillus and acetic acid content, which were capable to improve intestinal mucosal immunity and barrier function, thus maintaining intestinal health and improving production performance.