Oleanolic acid improves antioxidant capacity and the abundance of Faecalibacterium prausnitzii in the intestine of broilers

This study investigated the effect of dietary oleanolic acid (OA) addition on broiler intestinal morphology, intestinal antioxidant capacity, changes in cecum microbiota, and the relationship between microbiota and antioxidant capacity. A total of 288 Arbor Acres broilers at 1-day-old broilers were reared, and they were randomly divided into four groups. The control and experimental groups were fed the basal diet and the basal diet supplemented with 50, 100, and 150 mg/kg OA for a total of 42 d respectively. The results showed that OA does not affect the performance of broiler chickens. The OA supplementation increased the ratio between jejunum villus height and crypt depth (P < 0.05). The expression of antioxidant enzymes (GSH-PX and CAT) and antioxidant-related genes (HO-1, NQO1, Nrf2, and CAT) was significantly increased in the jejunum and cecum (P < 0.05). In addition, jejunal T-AOC activity (P < 0.05) and cecum antioxidant-related gene GPX-1 expression (P < 0.01) were significantly increased. The expression of oxidation-related genes (NOX and ROMO1) was significantly down-regulated in both jejunum and cecum (P < 0.05). The addition of 150 mg/kg of OA increased the relative abundance of potentially beneficial bacteria and Faecalibacterium prausnitzii was significantly and positively correlated with the expression levels of antioxidant-related genes. In conclusion, the addition of OA to the diet may improve the intestinal antioxidant capacity and modulate the intestinal microbiota of broilers. Moreover, OA improved intestinal antioxidant capacity by increasing the relative abundance of F. prausnitzii.