217 Influence of F18+Escherichia Coli challenge on jejunal mucosal immunity of nursery pigs at different ages

Abstract The objective of this study was to test a hypothesis that nursery pigs would be more susceptible to F18+E. coli for their impacts on the jejunal mucosal immunity at their early age. Thirty-two pigs were weaned at 21 d of age (6.8 ± 0.3 kg) and allotted to 2 treatments (NC: no challenge; PC: F18+E. coli challenge) in a randomized complete block design, with initial body weight and sex as blocks, and fed for 14 d (in 2 phases: 7 and 7 d, respectively) or 28 d (in 3 phases: 7, 13, and 8 d, respectively). On d 7, pigs were orally inoculated with F18+E. coli (1.5 × 1010 CFU). At 35 d and 49 d of age, pigs were euthanized to collect jejunal mucosa and tissue for jejunal mucosal immunity. Treatments were arranged in 2 × 2 factors with age (d 14 or 28 post-weaning) and F18+E. coli challenge (saline solution or F18+E. coli at 1.5 × 1010 CFU). Pigs had smaller (P < 0.05) jejunal IgA at 35 d of age than at 49 d of age. Pigs had greater (P < 0.05) jejunal MDA at 35 d of age than at 49 d of age. Pigs in PC had smaller (P < 0.05) jejunal IL-8 than those in NC. Jejunal TNF-α of pigs was not different between NC and PC at 35 d of age, whereas pigs in PC had smaller (P < 0.05) jejunal TNF-α than those in NC at 49 d of age. Pigs in PC had greater (P < 0.05) jejunal IL-6 than those in NC at 35 d of age, whereas jejunal IL-6 of pigs was not different between NC and PC at 49 d of age. Pigs in PC had smaller (P < 0.05) jejunal villus height to crypt depth ratio than those in NC. Pigs in PC had smaller (P < 0.05) jejunal ratio of cell proliferation than those in NC at 35 d of age, whereas jejunal ratio of cell proliferation of pigs was not different between NC and PC at 49 d of age. Jejunal villus height of pigs was not different between NC and PC at 35 d of age, whereas pigs in PC tended to have smaller (P = 0.072) jejunal villus height than those in NC at 49 d of age. In conclusion, the F18+E. coli challenge had greater negative influence on the jejunal immune response and cell proliferation in the jejunum at 35 d than at 49 d of age, whereas a negative impact on intestinal morphology could be seen at 49 d of age, indicating that pigs were more susceptible to F18+E. coli at their early age.