J. World Poult. Res., 10(2S): 184-194, 2020
ducklings subdivided into six equal groups (1-6) by
Experimental design and sampling
Samples were obtained according to the research
design from the different districts in Kafr El-Sheikh
Governorate, Egypt. In total, 50 litter samples, 200 cloacal
swabs from integrated duck farms and 69 water samples
from fish ponds, 60 liver samples were taken from
sacrificed ducks from different fish farms. All samples
were labeled and transported to the laboratory. (Animal
Health Research Institute, Kafr El-Sheikh provisional
laboratory, Egypt). The samples were subjected to
Salmonella isolation and identification.
ranking methods. At the 7th day, the first five groups were
inoculated orally (using 1-ml sterile feeding tube via crop)
9
each of S. Bargny, S. Tshingwe, S. Uganda, S. Kentucky,
and S. Enteritidis respectively, while the 6th group kept as
uninfected control and was similarly inoculated orally with
physiological saline. Each group was reared separately in
wire-floored batteries and fed on commercial ration which
contain the nutritional requirement for Pekin duckling.
Feed and water were given ad.lib. All ducklings were kept
under observation for signs and deaths up to 3 weeks of
age. Cloacal swabs were collected for detection of fecal
shedding from all groups during the first 3 days post-
inoculation (PI), then at the weekly interval at the 2nd and
the 3rd week PI. Moreover, at the end of the 2nd and 3rd
week, two randomly selected ducks were sacrificed from
each group for postmortem, bacteriological and
histopathological examination. Initial and final body
weight, feed consumption, body weight gain and feed
conversion rate were calculated at a weekly interval as
averages. Percentages of the average values of the infected
groups were also calculated relative to the average values
of the uninfected control group to allow better comparison.
Also Re-isolation of salmonellae from dropping, liver,
spleen and gall bladder of experimentally infected seven-
day-old ducklings.
Isolation and identification of different
Salmonella serotypes
Isolation of different Salmonella was applied on
litter. Briefly, 25 g of litter samples were prepared by
mixing in a sterile flask with 225 ml phosphate buffer
saline (PBS, Bio Basic, Canada). Water samples obtained
through inverting a 500 ml sterilized flask in 30 cm (Abd-
water samples were clarified by centrifugation (centrifuge-
Universal- Germany) at 5000 rpm for 5 minutes. Cloacal
swabs and liver samples (A sterile cotton swabs stabbed
into liver parenchyma) by using nutrient broth (Oxoid,
UK), where 1 ml of all of these samples inoculated in
nutrient broth and incubated at 37ºC for 24 hr. Then, 1 ml
of incubated broth was inoculated into selenite F broth
(Oxoid, UK) and incubated at 37 ºC for 24 hr. a loopful
from this broth were streaked onto Salmonella-shigella
(SS) agar (Oxoid, UK) and incubated at 37 ºC for 24 hr.
All the suspected pure colonies of salmonellae were
furtherly subjected to biochemical reactions (methyl-red,
Voges-Proskauer, indole and urea tests) according to
Salmonella isolates was finally identified according to
antiserum and Salmonella monovalent ”O and H”
antiserum (SINIF Co., Germany). Then a five Salmonella
isolates were employed to study the clinicopathological
picture in duckling.
Statistical analysis
The obtained numerical data were statistically
analyzed using SPSS software. Duncan's multiple range
test was used for testing significance of differences among
group means at p-value<0.05.
RESULTS
Results of salmonellae isolation are shown in table 1,
which revealed that 19 Salmonella isolates were recorded
from poultry litter, fish pond water, cloacal swabs of
integrated ducks and liver of integrated ducks at rates of 8,
2.9, 4 and 8.3%, respectively.
Comparative clinicopathological effects of
Salmonella isolates
All 19 Salmonella isolates were subjected to
biochemical identification and the results are summarized
and presented in table 2. The biochemically identified
Salmonella isolates were serologically identified by using
monovalent and polyvalent "O" and "H" Salmonella
antisera. Results are summarized and presented in tables 3
and 4. Nineteen Salmonella isolates included S. Kentucky
Fifty, one-day-old Pekin duckling were employed to
study the clinicopathological effects of the different
Salmonella isolates including S. Bargny, S. Tshingwe, S.
Uganda, S. Kentucky and S. Enteritidis in susceptible one-
week-old ducklings through oral inoculation. Eight
experimental ducklings were bacteriologically examined
and proved to be free from Salmonella. The remaining 42
185