[Efficacy of maternal Salmonella antibodies and experimental oral infection of chicks with Salmonella enteritidis].

Distribution of maternally transmitted Salmonella antibodies and their protective effects were studied in the progeny of broiler breeder birds which had been vaccinated with live S. Typhimurium and inactivated S. Enteritidis vaccines. Vaccination resulted in a significant increase of the antibody concentration in yolk of hatching eggs and in serum and jejunum of the progeny of immunized breeder birds. Higher antibody titres for isotypes IgG and IgA were still seen on day 21 of age. Antibody production of isotypes IgA and IgM by the chickens themselves was found between 14 and 21 days of age. Two challenge models (10(2) cfu/bird on day 1 of age and a seeder bird model, respectively) were used to evaluate the efficacy of maternal antibodies against challenge with S. Enteritidis. Using both models numbers of challenge organisms were lower in the caeca of the progeny of immunized parent birds between day 7 and day 21 of age (maximum about 1.5 log10 units) compared with control chicks. The results indicate the efficacy of maternally transferred antibodies but it remains the question of their practical relevance. The effects of acquired maternal antibodies on an active immunization of the progeny of immunized breeder birds with live Salmonella vaccines are discussed.