Koch’s postulate in reproduction of broiler coccidiosis by co-infection with eight most common...
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![Page 1: Koch’s postulate in reproduction of broiler coccidiosis by co-infection with eight most common Eimeria spp.: a model for future evaluation of new biologics](https://reader036.fdocuments.us/reader036/viewer/2022081604/577cc06f1a28aba711901724/html5/thumbnails/1.jpg)
Koch’s postulate in reproduction of broiler coccidiosis by co-infection with eight most common Eimeria spp.: a model for future evaluation of new biologics
By:Danielle B. Ayyash
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Establish a model of Koch’s postulate for reproducing coccidiosis in broilers
Using this model in future evaluation of new controlling biologics
Purpose:
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Groups ofBroilers
Number of Broilers Broiler age atChallenge (d)
Broiler age atSacrification (d)
Challenged
1 10 14 20
2 10 21 27
3 10 28 34
4 10 35 41
Control
1 10 _ 20
2 10 _ 27
3 10 _ 34
4 10 _ 41
Table 1. Description of the different treatments of broilers
Experimental Design :
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The esophageal Eimeria-challenge was with a total of 1.76x105 oocysts/bird
Eimeria inocula
E. acervulina, E. mivati, E. maxima, E. necatrix, E. hagani, E. praecox, E. tenella, and E. brunetti
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Evaluation of the Koch’s postulate during the 6 days incubation period following an Eimeria challenge at assigned dates of 14, 21, 28 & 35 d of age
Protocols for Anti-coccidial Susceptibility Testing (AST)
1. The mean percent of weight increase
2. The mean feed conversion ratio
3. The mean percent mortality,
Materials and Methods
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Materials and Methods
The scoring of the lesions was accomplished by a trained researcher, scoring “0” ‘1’, ‘2’, and ‘3’ (-ve, mild , moderate, severe )
4. The mean score of lesions
5. The mean oocyst counts per gram of intestine- 1cm of 4 different parts of intestine was rinsed in a saline solution to remove fecal material- Weighed- homogenized and put in a 35% NaCl solution for the floatation of oocytes. - floated oocytes were counted in a McMaster chamber
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Group1 of broilers
Age at assigned challenge (days)
Percentage of weight increase at 6 days period following each assigned challengeControls Challenged SEM2
1 14 96.3 88.2
10.0
2 21 69.0 54.53 28 41.2 31.74 35 28.8 20.2Mean 58.8a 48.6a
Table 2. Percentage of weight increase in the four control and the four Eimeria-challenged groups after 6 days of assigned challenges
1Each of the four control and four challenged groups had 10 birds2SEM is Standard Error of MeansaMeans in a row followed by the same alphabet superscript are not significantly different (P>0.05)
Results & Discussion
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Table 3. Feed conversion in the four control and the four Eimeria-challenged groups at 6 days-incubation period following the assigned challenges
Group1 of broilers
Age at assigned challenge (days)
Feed conversion during 6 days following challenge
Controls Challenged SEM2
1 14 1.1 3.0
0.3
2 21 1.7 3.3
3 28 2.1 2.5
4 35 2.1 3.7
Mean 1.7a 3.1b
1Each of the four control and four challenged groups had 10 birds2SEM is Standard Error of Meansa,bMeans in a row followed by different alphabet superscripts are significantly different (P<0.05)
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Table 4. Frequency of mortality in the four control and the four Eimeria-challenged groups at 6 days period following the assigned challengesGroup1of broilers
Age at assigned challenge (days)
Frequency of mortality (%) in controls and Eimeria-challenged birds at 6 days period following the assigned challengesControls Challenged SEM2
1 14 1 (10%)a 4 (40%)a
0.5
2 21 1 (10%)a 2 (20%)a
3 28 0 (0%)a 0 (0%)a
4 35 0 (0%)a 0 (0%)a
Mean 0.5 (5%)a 1.5 (15%)a1Each of the four control and the four Eimeria challenged groups had 10 birds. 2SEM is Standard Error of MeansaFrequencies in a row followed by the same superscript are not significantly different (P>0.05)
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Table 5. Mean score of lesions in different parts of the intestine in the four control and the four Eimeria-challenged groups at the end of the 6 days-incubation period following the assigned challenges Group1of broilers
Age at assigned challenge (days)
Intestinal part Mean score of lesions at 6 days period following each challengeControls Challenged SEM2
1 14 DuodenumJejunumIleumCecum
0.0a
0.0a
0.0a
0.0a
1.5b
1.1b
1.6b
1.1b
0.250.180.250.21
2 21 DuodenumJejunumIleumCecum
0.2a
0.0a
0.1a
0.2a
2.0b
1.7b
1.6b
1.6b
0.270.250.260.25
3 28 DuodenumJejunumIleumCecum
0.6a
0.3a
0.0a
0.0a
1.4a
1.6b
0.6b
0.9b
0.250.250.150.22
4 35 DuodenumJejunumIleumCecum
0.25a
0.0a
0.0a
0.0a
0.5a
0.38a
0.38a
0.13a
0.180.140.140.06
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Group of broilers
Age at assigned challenge (days)
Intestine part
Mean oocyst count per gram of intestinal organ at end of 6 days period following the assigned challengesControls Challenged SEM
1 14 DuodenumJejunumIleumCecum
0a
0a
0a
0a
42254b
67839b
112843b
96666b
9744161773534226708
2 21 DuodenumJejunumIleumCecum
0a
0a
0a
0a
33715b
36636b
41896b
48041b
858493431017314776
3 28 DuodenumJejunumIleumCecum
0a
0a
0a
0a
6578b
12321b
19029b
7309b
1438307545661978
4 35 DuodenumJejunumIleumCecum
0a
0a
0a
0a
15344a
6506b
2912a
2367a
69561569921756
Table 6. Mean oocysts count per gram of intestinal part in the four control and the four Eimeria-challenged groups at the end of 6 days period
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In Conclusion
The Koch’s Postulate for reproducing coccidiosis in broilers, by the 8 most common Eimeria spp
Allow for future development of new immuno-modulators and coccidiostats
- Significant statistical differences in most measured parameters between controls and challenged birds
- A trend of reduction in weight gain and in augmentation of mortality in challenged birds compared to controls.
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Thank you for your
Attention !