Effect of orally administered egg yolk antibodies on Salmonella enteritidis contamination of hen's eggs.

Abstract

SummaryThe influence of oral application of anti‐Salmonella egg yolk antibodies on the in vivoSalmonella contamination 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 two Salmonella enteritidis (S. enteritidis) strains. The whole egg powder was administered orally to a laying hen group. The effects of anti‐Salmonella egg yolk antibodies in this experimental group were compared with a control group. In experiment 1, hens were infected orally with 2 × 109 colony‐forming units (CFU) of S. enteritidis per 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 for S. enteritidis; egg shells, the albumen and the egg yolk were sampled separately. Results indicated that the rate of Salmonella contaminated eggs of laying hens – experimentally infected with S. enteritidis at an infection dose of 2 × 108 CFU/hen – could be reduced by oral administration of whole egg powder containing S. enteritidis‐specific antibodies. In the experimental group 13.3% of the eggs were Salmonella positive, 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 the Salmonella contamination rate of hens eggs. The protective effect may have been due to the antibodies raised by vaccination of hens against S. enteritidis.