Illicium verum extracts and probiotics with added glucose oxidase promote anti-oxidant capacity through up-regulating hepatic and jejunal Nrf2/Keap1 of weaned piglets.

Accumulating evidences indicate that plant extracts and probiotics are effective anti-oxidant substitutes which play important roles in animal production. However, the comparative study of the mechanism underlying the anti-oxidant property of Illicium verum extracts (IVE) and probiotics with added glucose oxidase (PGO) on piglets remains to be explored. This study evaluated the difference and the interaction effect of IVE and PGO on serum, liver and jejunum anti-oxidant capacity of weaned piglets. A total of 32 weaned piglets (Duroc × Landrace × Yorkshire) at the age of 28-d with an average body weight of 14.96 ± 0.32 kg were randomly divided into four treatments with eight replicates per treatment in a 2 × 2 factorial arrangement. Treatments included basal diet (IVE-PGO-), basal diet + 1000 mg/kg PGO (IVE-PGO+), basal diet + 500 mg/kg IVE (IVE+PGO-), and basal diet + 500 mg/kg IVE + 1000 mg/kg PGO (IVE+PGO+). All the piglets were housed individually for the 42-d trial period after 7-d adaptation. The piglets were euthanized at the end of the experiment and the liver and jejunum samples were taken and subjected to immunohistochemistry, western blotting, as well as anti-oxidant and, qRT-PCR analysis. Significant interactions were observed between IVE and PGO for total superoxide dismutase (T-SOD) and glutathione peroxidase (GSH-Px) in serum (42-d), liver and jejunum, malondialdehyde (MDA) in serum (21-d), mRNA and protein expression of Keap1 and Nrf2/Keap1 in the liver and jejunum (P < 0.05). Both IVE and PGO improved (P < 0.05) T-SOD and GSH-Px in the serum (42-d), liver and jejunum, and the mRNA and protein expression of Nrf2 and Nrf2/Keap1 in the liver and jejunum, but decreased (P < 0.05) MDA in the serum (21-d), mRNA and protein expression of Keap1 in the liver and jejunum. Immunohistochemical results confirmed that IVE and PGO enhanced the positive reactions of Nrf2, but weakened Keap1 both in the liver and jejunum. In conclusion, the results confirmed that Illicium verum extracts (500 mg/kg) and probiotics with added glucose oxidase (1000 mg/kg) can improve the anti-oxidant capacity of weaned piglets, and that the interaction effect between IVE and PGO is significant. At the same time, the fact that IVE and PGO activate the Nrf2/Keap1 in the liver and jejunum signaling pathway, suggest that they play an important role in the ameliorative anti-oxidant capacity of weaned piglets. Therefore, the combination of Illicium verum extracts and probiotics with added glucose oxidase could be recommended as a new potential alternative to antibiotics in piglets' diets.