Illicium verum and Eucommia ulmoides leaf extracts promote nutrient availability and antioxidant capacity in piglets by upregulating duodenal and jejunal Nrf2/TNF-α.

The effect of Illicium verum extracts (IVE) or Eucommia ulmoides leaf extracts (ELE) on nutrient availability, duodenal and jejunal antioxidant ability of Duroc ×Landrace × Yorkshire (DLY) and Chinese native Licha-black (LCB) piglets was investigated. Ninety-six piglets (48 DLY and 48 LCB respectively) without significant difference in body weight (11.22 ± 0.32 kg) were used in a 2 × 4 factorial design. Animals were randomly allocated to four treatments, and each had four replicates with three DLY and three LCB piglets. Treatments were basal diet (CON) and basal diet with 500 mg/kg IVE, 250 mg/kg ELE and 50 mg/kg chlortetracycline (CHL) respectively. Animals were placed individually for 7-days adaptation following 42-days test. Results showed the significant interaction (p < 0.05) between dietary treatments and pig species in activity of total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px), content of malondialdehyde (MDA), and α-tumour necrosis factor (TNF-α), nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf2/TNF-α at mRNA and protein level in duodenum and jejunum of DLY and LCB piglets. The IVE and ELE increased (p < 0.05) activity of GSH-Px and T-SOD, and the Nrf2/TNF-α at mRNA and protein level, however, the decreased (p < 0.05) MDA content, and TNF-α at mRNA and protein level in duodenum and jejunum were observed. The CHL decreased (p < 0.05) activity of GSH-Px and T-SOD, TNF-α and Nrf2 at mRNA and protein level in duodenum, but increased (p < 0.05) MDA content and Nrf2/TNF-α in jejunum. DLY piglets had higher (p < 0.05) nutrient digestibility (organic matter, crude protein and gross energy), availability (biological value and net protein utilization), MDA content, and TNF-α at mRNA and protein level in jejunum, and had lower (p < 0.05) activity of GSH-Px and T-SOD, and Nrf2 and Nrf2/TNF-α at mRNA and protein level in duodenum and jejunum than LCB. In conclusion, the 500 mg/kg IVE and 250 mg/kg ELE improved the nutrient availability, and the improvement of antioxidant capacity is realized by activating the Nrf2/TNF-α of duodenum and jejunum. The CHL had adverse effects on antioxidant ability of DLY and LCB piglets. The results showed that the nutrient digestion and absorption capacity of DLY were stronger than that of LCB piglets, but the antioxidant capacity was lower than that of LCB piglets. Therefore, the IVE and ELE are recommended as a new potential alternative to antibiotics in piglets' diets.