Production of IgY by layers injected with Salmonella typhimurium

In the present study, production of IgY and performance of layers immunised with Salmonella typhimurium were evaluated. Thirty 23-wk old layers (Lohmann Brown) with average body weight of 1.6 ± 0.03 kg. were randomly and equally divided into two groups. Both groups were placed in a specific pathogen free room equipped with an exhaust fan. The layers were placed in single battery cages with slightly tilted floor which allowed eggs to roll straight into the collecting tray. Lyophilized, attenuated whole cells of S. typhimurium strain [serotype: Somatic (O), antigen 1, 4, (5), 12, flagella (H) N12 phase I: 1; phase II: 1, 2 (Group B)] that were emulsified with Freund’s complete adjuvant were used to immunise the layers intramuscularly 3 times at 2-wk interval (treatment group). Layers in the control group were injected with a solution of sterilized phosphate-buffered saline (PBS) emulsified with an equal volume of Freund’s complete adjuvant. The experimental period lasted for 14 wks. Specific antibodies were detected by enzyme-linked immunosorbent assay. The results showed that the birds lost weight during the injection period, but the weights slowly increased in the following weeks. However,the weight of layers in the treated group remained lower (P<0.05) when compared to the period before injection. The loss in body weight of layers was the result of reduced feed intake, in particular during the injection weeks. Layers in the control group had a higher egg production,by about 10.1% than layers in the treatment group throughout the experimental period. The egg production for layers in treatment group showed a significant decrease (P<0.05) during the immunization period by 28.8%. The egg production significantly increased (P<0.05) to 71.9% after this period, but the production did not reach the level before immunisation. The weight of eggs of treated layers were significantly lower (P<0.05) than the control layers during the injection weeks. The egg mass was significantly reduced (P<0.05) in layers during the injection period, but increased during the postprandial period. IgY titre continued to increase after the first booster and reached a high level at about 4 wk postprandial and IgY level was maintained until the end of the experimental period. The specific IgY was about 9.6 mg/g of yolk, approximately 1% w/w of egg yolk. The present study showed that specific IgY antibodies were successfully raised against S. typhimuirum through injection of attenuated S. typhimurium whole cells to layers.