It has been demonstrated that it was possible, under the conditions of the former GDR (East Germany), to decisively decrease the occurrence of Salmonella in livestock by means of the consequent combination of a good management including hygienic measures and of immunoprophylactic measures. This is one of the most important conditions for reducing the risk of food poisoning in man. 2. If using Salmonella live vaccines, cross immunity can be put to use. 3. Amount and duration of Salmonella shedding by calves can be decreased using orally administered live vaccines. 4. The immunogenicity of the S. typhimurium mutant serving as vaccine strain for Zoosaloral "Dessau" was retained after its 60-MDa plasmid had been deleted.