Efficacy of Lactobacillus plantarum supplementation in broilers challenged with avian pathogenic Escherichia coli and Salmonella Typhimurium

Two experiments were conducted to determine the effects of Lactobacillus plantarum (DFM) on performance in broilers challenged with avian pathogenic Escherichia coli (APEC) and its effects on Salmonella colonization following S. Typhimurium challenge. In experiment 1, broilers were reared from d zero to 28 and orally challenged with 1 x 10(8) CFU of APEC on d 7. Treatments included a non-challenged positive control (PC), challenged negative control (NC), NC + 0.05, 0.10, or 0.20% DFM, and NC + 0.05% antibiotic (BMD). Body weight (BW) was not different among treatments. Mortality-corrected feed conversion ratio (FCRm) was increased with APEC challenge in comparison to the PC, while BMD returned FCRm to that of the PC (P <= 0.05). Treatment with 0.10% DFM resulted in the largest relative spleen weight (SW: % BW) at d 14, but also resulted in the lowest number of APEC associated mortalities, suggesting an enhanced immune response. In experiment 2, one-day-old broilers were orally challenged with 1 x 108 CFU of S. Typhimurium and fed a control diet (PC), or the same diet with 0.10 or 0.20% DFM. Intestinal samples were collected for determination of Salmonella colonization by the most probable number method at d 3 and d 7 post inoculation, and bioluminescence imaging using In-Vivo Imaging System at d 7 post inoculation. Treatment with DFM reduced total Salmonella content on d 7, but changes in bioluminescence were not significant. Overall, DFM treatment was concentration specific, but did result in positive responses to both APEC challenge and total Salmonella counts.