Effects of orally administered Escherichia coli Nissle 1917 on growth performance and jejunal mucosal membrane integrity, morphology, immune parameters and antioxidant capacity in early weaned piglets

The objective of this study was to assess the effect of orally administered Escherichia coli Nissle 1917 (EcN) on the jejunal health of weaned piglets that were unchallenged or challenged with porcine enterotoxigenic E. coli Abbottstown (EcA). A total of 40 weaned Landrace × Yorkshire piglets (5.83 ± 0.24 kg) were allocated to 4 groups with 10 barrows per group, following a 2 × 2 factorial design with 2 inclusion levels of EcN (daily oral administration of 2 mL sterile water or 2 mL EcN (109 cells/mL)) at 10:00 h) and 2 inclusion levels of EcA (daily oral administration of 2 mL sterile water or 2 mL EcA (109 cells/mL) at 14:00 h). Thus, there were four treatments: (1) control diet (C); (2) C + EcN (N); (3) C + EcA (A); (4) C + EcN + EcA (N + A). This experiment lasted for 21 d. The results indicated a significant interaction between EcN and EcA on growth performance and jejunal mucosal membrane integrity, morphology, immune parameters and the antioxidant capacity in 21-day-weaned piglets (P<0.05). The results that piglets in the A group had lowest feed conversion, daily weight gain, daily feed intake, jejunal villus height (P<0.05) among the 4 groups suggested that the oral administration of EcA decreased growth performance. The results that piglets in the A group had lowest mRNA levels of regenerating islet derived protein 3 gamma and transforming growth factor beta 1 (P<0.05), lowest protein levels of claudin-1, occludin, and zonula occludens-1 (P<0.05) and highest serum d-lactate concentration (P<0.05) among the 4 groups suggested that the oral administration of EcA damaged jejunal mucosal membrane integrity. The immune and antioxdant parameters results that orally administered EcA increased mRNA levels of interleukin (IL)-1β, IL-8, tumor necrosis factor (TNF)-α, and toll-like receptor (TLR) -4 (P<0.05), increased the concentrations of IgM, IgG, IL-1β, TNF-α, sIgA (P<0.05), and TLR-4, and decreased activities of superoxide dismutase and total antioxidant (P<0.05) suggested that EcA could make the jejunal mucosal membrane inflamed in early weaned piglets. Orally administered EcN tended to improved growth performance, jejunal villus height, the immune and antioxdant function, jejunal mucosal membrane integrity in piglet unchallenged or challenged with EcA. This improvement of the jejunal health and growth performance of piglets challenged with EcA by oral administration of EcN could be attributed to increased defense against harmful bacteria and improved epithelial barrier function. These results demonstrated that EcN could be used in early-weaned piglets to prevent intestinal infection by the pathogenic bacteria EcA.