Vaccination versus antimicrobials to prevent Porcine Proliferative Enteropathy: associated costs and effects on piglets' growth, health, and serological performance.

Introduction: This study evaluated vaccination and prophylactic use of antimicrobials as strategies to prevent Porcine Proliferative Enteropathy (PPE) during nursery and growth-finishing phases.

Methods: Three hundred weaned piglets (~ 29 days old) were distributed into groups: NVMED - no vaccinated against Lawsonia intracellularis but in-feed medicated with antimicrobials (amoxicillin, florfenicol, lincomycin, spectinomycin and tilmicosin); VMED - vaccinated and in-feed medicated; VNMED - vaccinated but no in-feed medicated. Piglets were vaccinated at weaning (Porcilis^® Ileitis, MSD Animal Health). The following variables were assessed: growth and health performance, anti-L. intracellularis IgG levels, L. intracellularis fecal shedding, Pneumonia and Pleurisy Index (PPI) at slaughter, antimicrobial consumption and costs, and vaccination expenses.

Results: Average daily gain (ADG) at the nursery phase was lower in VNMED group (p < 0.01); however, there was no treatment effect on feed conversion, ADG, and body weight at growth-finishing phase (p ≥ 0.23). Similar anti-L. intracellularis IgG levels were found for VMED and VNMED groups at all evaluated moments (p = 0.01). L. intracellularis was only detected in feces samples from 4/90 tested piglets and no difference in health performance was found (p > 0.05). Groups presented PPI < 0.89. In-feed antimicrobial consumption and related costs were 3 to 3.5-fold higher for NVMED and VMED groups compared to VNMED group.

Discussion: The prophylactic administration of antimicrobials used in this study did not affect the serological performance post-vaccination against L. intracellularis. Additionally, vaccine use to prevent PPE reduced the antimicrobial consumption and related costs by ~70%, with no impairments on production outputs.