Dietary enzymatically treated Artemisia annua L. supplementation improved growth performance and intestinal antioxidant capacity of weaned piglets

•Dietary supplementation with 2 g/kg enzymatically treated Artemisia annual L. could increase average daily gain and decrease the incidence of diarrhea in weaned pigs.•The optimal dose of enzymatically treated Artemisia annual L. in weaned pigs in the current study was 2 g/kg.•Diet supplemented with enzymatically treated Artemisia annual L. improved the intestinal morphology.•Dietary enzymatically treated Artemisia annual L. supplementation enhancd intestinal antioxidant capacity of weaned piglets by activating related gene and protein expressions of Nrf2/ARE-mediated pathway. The present study determined the optimal dose of enzymatically treated Artemisia annua L. (EA) and investigated the effect of dietary EA supplementation on the intestinal antioxidant activity of weaned piglets. Firstly, a total of 300 piglets with an average body weight of 5.62 ± 0.36 kg (21 days of age) were randomly allocated to 5 dietary treatments, including CON, EA1, EA2, EA3, and EA4 groups (basal diet supplemented with 0, 0.5, 1, 2, 4 g/kg EA, respectively). At 50 days of age, growth performance and the incidence of diarrhea were measured. The results showed that average daily gain was significantly increased (P < 0.05) and the incidence of diarrhea was significantly decreased (P < 0.05) in EA3 group compared to CON group. Therefore, we considered 2 g/kg EA as the optimal dose in pig diet in the present study. Then, 12 piglets from CON and EA3 groups (6 piglets per group) were slaughtered at 51 d for further investigation in vivo. Diet supplemented with 2 g/kg EA decreased (P < 0.05) crypt depth, increased (P < 0.05) villus height and villus height to crypt depth ratio in both jejunum and ileum of piglets. Dietary EA supplementation increased (P < 0.05) the activities of glutathione peroxidase (GPx) and total superoxide dismutase (T-SOD), decreased (P < 0.05) the concentrations of malondialdehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OHdG) in the serum. EA group had higher (P < 0.05) total antioxidant capacity (T-AOC) level and T-SOD activity, the abilities to inhibit hydroxyl radical and superoxide radical in both jejunum and ileum than CON group. EA diet increased (P < 0.05) jejunal GPx activity and ileal glutathione concentration, decreased (P < 0.05) ileal MDA concentration. EA group showed lower inducible nitric oxide synthase activities in both jejunum and ileum than CON group. The mRNA expressions of antioxidant related genes (Gpx1 mRNA in the jejunum, and Sod1, Nfe2l