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Effects of challenge dose
on faecal shedding of Salmonella enteritidis in
experimental infected chickens
Olayinka Olabisi Ishola
Department
of Veterinary Public Health and Preventive Medicine,
University of Ibadan, Ibadan, Nigeria. E-mail:
olayinkaishola@yahoo.com. Tel.: 234-803-697-6193. Fax:
234-2- 8103043.
Accepted
17 February, 2009 |
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Experimental infection of chickens with Salmonella
enteritidis is often achieved by oral inoculation of
live bacteria to caged chickens. Less information is
available on influence of amount of Salmonella a
chicken is exposed to during infection on the proportion
that is eventually eliminated in faeces. This study
evaluated the effects of challenge dose of S.
enteritidis on faecal shedding by experimentally
infected chickens. Twenty four specific-pathogen-free hens
were divided into three groups of eight. The first two
groups were orally challenged with a dose of 1.3 x 104
and 1.3 x 108 colony forming units (cfu) of S.
enteritidis per hen, the third group was uninfected.
Faecal samples were collected weekly for 5 weeks and
cultured. Levels of S. enteritidis recovered
from hens infected with 108 cfu/ml S.
enteritidis were significantly higher (P < 0.05) than
from 104 cfu/ml group. Rate of faecal shedding
decreased from 100 to 75 and 37.5% at weeks 1, 2 and 4
respectively in 108 cfu infected hens.
Intermittent shedding pattern was observed in the 104
cfu group. Hence, Salmonella contamination of poultry
environment continues in sub-clinical infection. Multiple
faecal sampling of flocks may be necessary to know their
Salmonella status and in vaccine assessment.
Key
words:
Salmonella enteritidis, chickens, faecal
shedding, challenge dose, infection. |
