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Probiotic feed additives have to undergo a strict assessment according to EU regula-tions, including the evaluation of the influence on the gut microflora of the host animal. A probiotic strain of the genus Enterococcus faecium and two different host animal species, young calves and newly hatched turkeys, were chosen as a test model for the establishment of schemes for feeding trials. Investigations included faeces samples and pooled swab samples of faeces as well as samples from gut sections derived from diagnostic slaughtering. The samples were tested for aerobic total count, for enterococci count and for Enterobacteriaceae and E. coli. The test schemes were appropriate for the evaluation of the influence of the probiotic feed additive on the physiological gut microflora of the host animals. Additional information could be gathered concerning safety aspects and effectiveness.

One of the most promising genotyping methods for microorganisms is the AFLP (amplified fragment length polymorphism)-analysis, originally developed to genotype plants. The AFLP method has a high discriminatory power and an excellent reproducibility. Thus it is suitable for solving taxonomic and epidemiological questions. AFLP analysis was used to reveal the genetic diversity of Campylobacter (C.) jejuni strains from turkeys. The aim was to detect and genotype C. jejuni strains on individual turkeys throughout the complete slaughter process. A broad spectrum of genotypes was detectable on the turkey skin at the beginning of the slaughter line. At the end of the slaughter process-after chilling, only a diminished spectrum of genotypes was detectable by AFLP-analysis, suggesting, that slaughter specific environmental stressors may exert a selective pressure on the strain diversity. Our results proved, that AFLP analysis is an excellent tool for subtyping large numbers of Campylobacter strains.

A report is given on the development and function of the autochthonous intestinal flora in poultry. The relevance of this flora for infections with Salmonella spp., both following egg transmission and oral intake from the 4th to 6th week of life is discussed.