EFFICACY OF MATERNAL SALMONELLA ANTIBODIES AGAINST 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 bir ds which had been vaccinated with live S. Typhimurium and inactivated S. Enteritidis vaccines. Vaccination resulted in a significant increas e 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. Ant ibody production of isotypes IgA and IgM by the chickens themselves wa s 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 wit h S. Enteritidis. Using both models numbers of challenge organisms wer e lower in the caeca of the progeny of immunized parent birds between day 7 and day 21 of age (maximum about 1.5 log(10) units) compared wit h control chicks. The results indicate the efficacy of maternally tran sferred antibodies but it remains the question of their practical rele vance. The effects of acquired maternal antibodies on an active immuni zation of the progeny of immunized breeder birds with live Salmonella vaccines are discussed.