[Administration of autochthonous intestinal microflora--a method to prevent Salmonella infections in poultry].

Administration of autochthonous intestinal microflora to chicks during the early period after hatching (Competitive Exclusion) is a widely accepted prophylactic method to control Salmonella infections in poultry. The method of competitive exclusion consists in an administration of intestinal flora from healthy adult birds to chicks during the first hours or days of their life. Use of competitive exclusion cultures will considerably enhance resistance to all Salmonella serovars colonising the chicken intestine and reduce shedding of salmonellas by infected animals. However, sole use of this method does not completely prevent Salmonella colonisation of the animals nor elimination of the agents from poultry flocks. At present, only complex competitive exclusion cultures whose composition has not been defined are capable of inducing an adequately high and reproducible efficacy. Effective preparations with a defined composition have not yet been developed because knowledge of the mechanisms of action of the competitive exclusion cultures as well as the effective species of the various bacterial genera is still inadequate. Since in approval procedures, the competitive exclusion cultures with a non-defined composition can neither be classified as medicines nor feed additives nor vaccines, WHO has proposed to establish the product category "Normal Gut Flora" (WHO, 1994). Basic prerequisites for an effective reduction of non-host-adapted Salmonella serovars in, or their elimination from poultry flocks are the performance and assurance of effective hygienic measures. Like the methods of immunisation using live or inactivated Salmonella vaccines in poultry, the method of competitive exclusion constitutes an additional prophylactic method that may be applied directly in the animal to enhance its resistance to Salmonella infection.