EN
The studies were carried out on 570 broiler chickens, 600 layers and 400 that were hatching eggs. The rate of infection by Campylobacter sp. and the dynamics of the alimentary tract colonization were determined under field conditions. In addition the samples of feed, water and litter were collected for the studies during the production period. Depending on the age of broiler chickens, the rate of infection with Campylobacter sp. ranged from 30.8 (on day 14) after hatching to 66.7% on day 47 after hatching. In layers the infection comparised 60.3% of birds under study. Among the isolated strains C. jejuni biotype 1 predominated. The eggs of newly hatched chicks, feed and water were free from Campylobacter sp. However, the bacteria were isolated from litter. The data obtained in this study exclude vertical transmission of the germs, but confirm that litter contributes to the spread of flock infection.