256 Effects of Lactobacillus Fermentate Replacing Bacitracin on Biomarkers Associated with Bacterial Cell Wall Recognition and Intestinal Integrity in Pigs

Abstract

Abstract Two experiments were conducted to evaluate the efficacy of Lactobacillus fermentate (LBF) as postbiotic on immune response and barrier function in jejunal mucosa of nursery pigs challenged with F18+Escherichia coli. Sixty-four pigs (32 barrows and 32 gilts) weaned at 21 d of age with 7.9 ± 0.5 kg in Exp. 1 (n = 32) and 6.6 ± 0.7 kg in Exp. 2 (n = 32) were allotted based on a randomized complete block design with sex and initial BW as blocks. The treatments were NC: no challenge/no supplement; PC: E. coli challenge/no supplement; AGP: E. coli challenge/bacitracin (30 g/t feed); and PBT: E. coli challenge/postbiotic (2 kg/t feed). Pigs were fed a basal diet for 28 d, formulated to meet the nutrient requirements of NRC (2012). At d 7, the challenged pigs were orally inoculated with F18+E. coli. At d 28, pigs were euthanized to collect jejunal tissue to analyze gene expressions involved in bacterial cell wall recognition, immune response, and intestinal barrier function. Data were analyzed using the Proc MIXED of SAS 9.4. The PC tended to reduce (P = 0.097) the relative expression of PGLYRP2A (1.12 to 0.76) and increased (P < 0.05) TLR4 (0.98 to 1.67) and NOD1 (0.99 to 1.56) compared with NC. The AGP tended to increase (P = 0.074) PGLYRP2A (0.76 to 1.15) and tended to reduce (P = 0.099) PGLYRP3 (1.21 to 0.82) compared with PC. The PBT increased (P < 0.05) PGLYRP4 (0.86 to 1.53) compared with PC. The AGP tended to reduce (P = 0.085) TLR4 (1.67 to 0.98) compared with PC. The AGP and the PBT reduced (P < 0.05) NOD1 (1.56 to 0.98 and 0.97, respectively) compared with PC. The PC tended to increase (P = 0.079) CD14 (1.13 to 2.13) compared with NC, however, PBT tended to reduce (P = 0.091) it (2.13 to 1.27) compared with PC. The AGP increased (P < 0.05) interferon-γ (1.13 to 1.21) and the PBT tended to increase (P = 0.096) it (1.13 to 1.63) compared with PC. The AGP tended to increase (P = 0.082) claudin-1 (0.85 to 1.81) compared with PC. In conclusion, F18+E. coli challenge upregulated the expression of pathogen recognition genes, including TLR4, CD14, and NOD1, which can increase the production of cytokines associated with pro-inflammatory response. The AGP showed a trend towards increasing the intestinal barrier function, possibly by increasing the expression of interferon-γ and reducing the expression of genes associated with pathogen recognition. The PBT enhanced the immunocompetence of nursery pigs by increasing the expression of interferon-γ and PGLYRP4, and reducing the expression of genes associated with pathogen recognition including NOD1 and CD14, which may indicate a reduction of the pathogen invasion.