Effect of a live attenuated vaccine against Lawsonia intracellularis in weaned and finishing pig settings in Finland.

Background: The intracellular bacterium Lawsonia intracellularis is an important pathogen in modern swine production. The aim of this study was to investigate the effect of a live attenuated L. intracellularis vaccine (Enterisol Ileitis) on the health and production parameters of weaned and finishing pigs in a commercial Finnish 850-sow farm with diagnosed L. intracellularis infection. The herd was free from enzootic pneumonia, swine dysentery, progressive atrophic rhinitis, sarcoptic mange and salmonellosis. Four weekly groups of approximately 500 piglets were included in the study for a total of approximately 2000 piglets. Half of these piglets were vaccinated at 3 weeks of age and the other half served as controls. The study piglets were ear-tagged with individual numbers and colour-coded and were individually weighed at weaning (4 weeks), delivery to the finishing farm (12-14 weeks) and at slaughter. Mortality, symptoms of diseases and medications of the study piglets were registered in the nursery and finishing unit. Feed conversion rate was calculated for the finishing period and lean meat percentage was measured at slaughter.

Results: Vaccinated piglets had a higher live weight than unvaccinated piglets at delivery to the finishing unit (+ 1.18 kg, P = 0.002) and at slaughter (+ 3.57 kg, P < 0.001). The daily weight gain of vaccinated piglets was better than unvaccinated piglets in the nursery (+ 14.8 g/d, P = 0.013) and in the finishing unit (+ 30.9 g/d, P < 0.001). Vaccination had no effect on feed conversion rate or lean meat percentage (P = 0.102). Altogether, 3.9 and 4.6% of the pigs were medicated for different reasons in the vaccinated and control groups, respectively. The return on investment for the vaccination was calculated to be 0.41.

Conclusions: Immunisation of piglets with a live attenuated L. intracellularis vaccine resulted in higher meat yield in pig production via significantly higher live weight and average daily weight gain in a Finnish specific pathogen-free setting.