Studies on translocation, acute oral toxicity and intestinal colonization of potentially probiotic lactic acid bacteria administered during calf rearing

In order to test the harmlessness of potentially beneficial bacterial strains when raising young calves, their safety level should be verified before they are included into a probiotic formulation. In the present study, an inoculum composed of three lactic acid bacteria of bovine origin, Lactobacillus casei DSPV 318T, Lactobacillus salivarius DSPV 315T and Pediococcus acidilactici DSPV 006T, was evaluated to define its acute oral toxicity and capacity to colonize, remain in the gastrointestinal tract and translocate to the organs in the internal medium.The inoculum was orally administered to a group of experimental calves in doses of 109 CFU/kg/day suspended in a NaCl 0.15 M solution. A control group received only a NaCl solution as placebo. The results showed that the bacteria of the used probiotic inoculum did not translocate to the internal medium and that there were no adverse effects on the general health state, weight gain and feed consumption in the animals treated with the inoculum. This situation suggests that the strains used are not pathogenic and will be probably safe if used as a food additive in calf diets.