Effect of Orally Administered Egg Yolk Antibodies onSalmonella enteritidisContamination of Hen's Eggs

Summary The influence of oral application of anti‐Salmonellaegg yolk antibodies on thein vivoSalmonellacontamination rate of eggs laid by experimentally infected hens was investigated. Antibody containing egg powder was obtained by spray drying of whole egg contents from hens immunized with twoSalmonella enteritidis(S. enteritidis) strains. The whole egg powder was administered orally to a laying hen group. The effects of anti‐Salmonellaegg yolk antibodies in this experimental group were compared with a control group. In experiment 1, hens were infected orally with 2 × 109colony‐forming units (CFU) ofS. enteritidisper hen, compared with experiment 2 with an infection dose of 2 × 108 CFU/hen. Eggs laid by the experimental and the control groups were monitored forS. enteritidis; egg shells, the albumen and the egg yolk were sampled separately. Results indicated that the rate ofSalmonellacontaminated eggs of laying hens – experimentally infected withS. enteritidisat an infection dose of 2 × 108 CFU/hen – could be reduced by oral administration of whole egg powder containingS. enteritidis‐specific antibodies. In the experimental group 13.3% of the eggs wereSalmonellapositive, which was significantly different from 29.4%Salmonella‐positive eggs in the control group (P ≤ 0.001). The use of antibody containing whole egg powder as a feed additive may be an alternative way to reduce theSalmonellacontamination rate of hens eggs. The protective effect may have been due to the antibodies raised by vaccination of hens againstS. enteritidis.