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Protection conferred by a live Salmonella Enteritidis vaccine against S. Enteritidis during the laying period

Y. D. HUBERMAN, A. V. VELILLA and H. R. TERZOLO
INTA EEA Balcarce, Animal Production, Bacteriology, CC 276, 7620, Balcarce, Argentina.

E-mail:yhuberman@balcarce.inta.gov.ar

Salmonellosis caused by Salmonella Enteritidis is considered to be emerging zoonoses, which is often associated with poultry products such as meat or eggs.

This study was carried out in order to evaluate the performance of a Salmonella Enteritidis vaccine, Tad Salmonella Vac E® (Lohmann Animal Health, Germany) to prevent the disease in laying hens throughout entire laying period.

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Methodology

Chickens: Salmonella free 1-day old commercial layer female chicks (Lohmann Brown).

Vaccination Route: By gavage into the crop.

Vaccination Plan: 1, 2 or 3 oral doses (Table 1).

Vaccination Dose: 1 to 5 x 10⁸ Colony-Forming Units per dose.

Faecal Samplings: 5 times by cloacal swabbing.

Organs Cultured: Livers, Ovaries, Spleens and Caeca.

Culture media: Brilliant Green plus Nalidixic Acid Agar, XLDT4 Agar and Tetrationate Broth.

Experimental design

Challenge strain: Virulent S. Enteritidis 285/94 Nalidixic Acid Resistant.

Challenge Dose: 2 to 5 x 10⁹ Colony-Forming Units per dose.

Trial 1: 114 chickens challenged at the 29^th week of life.

At 5^th day Post Challenge: 4-6 chickens were sacrificed.

At 10^th day Post Challenge: 4-6 chickens were sacrificed.

At 15^th day Post Challenge: All remaining chickens were sacrificed.

Trial 2: 147 chickens challenged at the 55^th week of life.

At 5^th day Post Challenge: 4-6 chickens were sacrificed.

At 15^th day Post Challenge: All remaining chickens were sacrificed.

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Results:

Reduction of the excretion of S. Enteritidis in the faeces (Figure 2)
Lower S. Enteritidis isolation rate from organs (Figure 3)
Improvement of egg production rate after challenge (Figure 4).

Table 1. Vaccination plan. Chicken were orally vaccinated with Tad Salmonella Vac E® by gavage into the crop.

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Conclusion

Three oral doses of Tad Salmonella Vac E® at 1^st day, 6^th- 8^th weeks, and 16^th-18^th weeks are recommended to afford protection against S. Enteritidis throughout the whole laying period.

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