85 Vaccination Mitigates Performance Losses During a Lawsonia Intracellularis Experimental Challenge

Lawsonia intracellularis is endemic to swine herds worldwide. Currently, vaccination is one of the few strategies available to mitigate L. intracellularis. Thus, this study aimed to characterize the impact of vaccination on growth performance and disease severity during experimental challenge. Thirty-six L. intracellularis negative barrows were assigned to treatment groups as follows (n = 12/trt): 1) nonvaccinated, L. intracellularis negative (NC); 2) nonvaccinated, L intracellularis challenged (PC); and 3) L. intracellularis challenged, vaccinated (Enterisol® Ileitis, Boehringer Ingelheim) at 1 week postweaning (VAC). On days post inoculation (dpi) 0 (7 weeks post-weaned) PC and VAC pigs were inoculated with L. intracellularis. Individual feed disappearance and BW were recorded weekly and all pigs were euthanized at dpi 21. Post-inoculation, ADG was reduced in PC (P < 0.001) and VAC (P = 0.001) pigs compared with NC pigs. Average daily gain was additionally reduced in PC pigs compared with VAC pigs (P < 0.001). Similarly, ADFI was reduced in PC (P < 0.001) and VAC (P = 0.029) pigs compared with NC pigs, and further reduced in PC pigs compared with VAC pigs (P = 0.032). Overall G:F was reduced in PC pigs compared with NC (P < 0.001) and VAC (P = 0.015) pigs, which did not differ. For antibody response and fecal shedding, NC pigs remained negative. Antibody responses and fecal shedding were lower in VAC pigs compared with PC pigs (P < 0.05). Ileal gross lesion severity was greater in PC pigs compared with VAC (P = 0.018) and NC (P = 0.003) pigs, which did not differ. Similarly, ileal lesion length was greater in PC pigs compared with NC (P = 0.007) and VAC (P = 0.045) pigs. Microscopic lesion severity was greater in PC pigs compared with both PC and VAC pigs (P < 0.05). Taken together, these data characterize the impact L. intracellularis has on growth performance of pigs and highlight the importance of vaccination to prevent disease associated performance losses.