Abstract
Campylobacter jejuni/coli strains from 164 chickens were serotyped by the methods previously described by Penner et al. and Lior et al. The chickens were sampled during breeding from hatching to the age of 42 weeks. The birds were housed, in two separate groups, under different environmental conditions, (for comparison of the effect of hygienic precautions on the transmission of the bacteria during breeding). In the group where the hygienic conditions could be controlled to a greater extent, the chickens became colonized later in the breeding chain and with only one single campylobacter strain. Once campylobacter appeared in the group housed at the breeding farm, the birds were colonized with heterogenous antigenic strains. All birds in this group were colonized with more than one strain. By identifying campylobacter strains from chickens during breeding, it was shown that the hygienic conditions are very important for the production of chickens free from campylobacter, or for minimizing the number of colonizing strains.