The objective of this investigation was to study if different feeding strategies influence experimental infections of pigs with Lawsonia intracellularis, the causative agent of proliferative enteropathy. In three sequential trials, a total of 144 weaned pigs were fed five different diets all made from a standard diet based on wheat and barley as carbohydrate source and soybean as protein source. The five diets were: a standard diet (fine ground and pelleted), the standard diet fed as fermented liquid feed, the standard diet added 1.8% formic acid, the standard diet added 2.4% lactic acid and a diet similar to the standard diet (made from the same ingredients), but fed coarse ground. Twenty-four pigs on each diet were orally inoculated with L. intracellularis and growth performance and faecal excretion of bacteria were monitored. Twenty-four pigs fed the standard diet were included as not experimentally infected controls. Pigs in the first two trials were sacrificed 4 weeks post-inoculation, whereas animals in the third trial were sacrificed after 5 weeks. Pigs in all experimentally infected groups excreted L. intracellularis. The fermented liquid diet delayed the excretion of L. intracellularis and furthermore, pigs fed the standard diet supplemented with lactic acid had limited pathological lesions when the intestines were examined 4 weeks after inoculation. The growth performance was reduced in pigs experimentally challenged with L. intracellularis, however the prevalence and severity of diarrhea was limited.