The role of the specific immune response on cecal colonization of slow-growing broiler chickens reared on litter contaminated by Campylobacter jejuni

anglais. The aim of this experiment was to study the relation between the specific immune response and infection of slow-growing broiler chickens reared on straw litter contaminated by Campylobacter jejuni. The 11-weeks experiment was carried out in a 45 m2 broiler house with 500 chickens from 1 day of age, which had access to an open-air range. Litter contamination was performed before the setting up of the chicks by rearing campylobacter-positive cocks. These birds were also used to contaminate the open-air range during one week before the exit of the chickens, at 5 weeks of age. Blood samples were taken weekly on 20 chickens for anti-campylobacter IgG quantitative measurements on serum. Chickens were then euthanized and cecal contents and bile were collected for Campylobacter enumeration and anti-campylobacter IgA quantification, respectively. A high serum anti-campylobacter IgG titer of 110.13 was measured in one-day-old chicks. The IgG antibodies level significantly decreased to 5.60 at 28 days of age which coincided with the onset of Campylobacter infection in the flock. A significant reduction of the cecal colonization from 11 weeks of age was correlated with the increase in biliary IgA titers. These results suggest that the 2-3 week’s delay generally observed in poultry production before flock infection by Campylobacter may be, at least partly, explained by the protective effect of maternal antibodies. The increase of secretory immune response as bird age may help to limit Campylobacter population in the chicken gut.

Sélection d’un complexe enzymo-bactérien antagoniste de Campylobacter ssp. pour l’élevage, sur parcours extérieur, de poulets de chair