Purpose: The aim of the present work was to investigate the effect of a probiotic L. acidophilus La-5 fraction on pigs to protect against Salmonella infection.
Methods: Six-week-old piglets were acclimatized at the animal facility for 14 days prior to inoculation with Salmonella Typhimurium SA941256. Two different protein concentrations of the L. acidophilus La-5 fraction were administered to two groups of 6 Salmonella-free piglets. After 7 days on this feeding regime, piglets were inoculated with 1.5 x 107 CFU of S. Typhimurium and the feeding regime was continued for 4 days post-infection. Bacteriological and molecular analyses were performed to detect S. Typhimurium in rectal swabs 4 days post-infection and in different tissues after euthanization.
Results: Salmonella was not present in rectal swabs after 48 h post-infection in piglets fed with the probiotic fraction containing a high protein concentration. Moreover, the bacterium was not found in the ileum and jejunum of these piglets. No statistically significant differences (P < 0.05) were found in the numbers of Salmonella in caecum and the contents of jejunum, ileum and caecum compared to non-treated piglets. However, the Salmonella amount in the contents was 1-log CFU less compared to non-treated piglets. Salmonella was detected by real-time PCR in the ileum of non-treated animals but not in piglets fed with the high-protein probiotic fraction.
Significance: Administration of bioactive peptides produced by probiotics reduces Salmonella carriage by pigs and may help reduce the burden of foodborne illness resulting from contamination of pork.