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Coccidiosis in commercial broiler chickens: Improving management of Eimeria species using live-vaccination or anticoccidial medication and developing and applying quantitative species-specific molecular assays.

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dc.contributor.advisor Barta, John
dc.contributor.author Snyder, Ryan
dc.date.accessioned 2021-01-07T20:26:18Z
dc.date.available 2021-01-07T20:26:18Z
dc.date.copyright 2021-01
dc.date.created 2020-12-21
dc.identifier.uri https://hdl.handle.net/10214/23704
dc.description.abstract Eimeria species are the cause of intestinal disease coccidiosis and impose a burden to commercial broiler production. The two most widely used coccidiosis prevention strategies include in-feed medication or live-vaccination. Commercial broiler flocks (n=95) in Ontario were sampled to determine oocyst cycling patterns to measure the success of medicated or vaccinated prevention programs at controlling disease. Vaccinated flocks (n=42) had more consistent oocyst shedding patterns with earlier and lower maximal counts than medicated flocks (n=53). Samples collected in the summer months peaked earlier in broiler production than winter months regardless of prevention program. Vaccinated flocks were on an antibiotic free program and at least some flocks suffered from bacterial necrotic enteritis, thereby reducing production efficiencies. One facility was identified with apparent anticoccidial-resistant Eimeria. This facility was seeded with sensitive Eimeria strains by vaccinating two consecutive flocks. Based on two Anticoccidial Sensitivity tests performed on isolates from before and after the seeding, the drug sensitivity profile improved. Oocyst cycling in flocks after seeding had shown improvement. However, neither the robustness nor longevity of this improvement could be assured because of the legislative requirements for Canadian broiler producer to remove litter at the end of flocks, thereby decreasing the carryover of drug-sensitive Eimeria population. The identification of the multiple Eimeria species typically found in a sample becomes essential because of their unique pathological characteristics and commercial impacts. Molecular assays were developed and tested provide relative species abundance. High throughput amplicon sequencing using Next Generation Sequencing and target quantification using Droplet Digital PCR both proved to be reliable diagnostic assays when targeting the cytochrome c oxidase subunit III gene within the mitochondrial genome. Finally, the ingestion rate of topically applied coccidiosis vaccines directly impacts the initiation of oocyst cycling required for broiler flocks to become protected from Eimeria challenge. Microspheres and fluorescein were used as tracers to measure the volume of material ingested by chicks following vaccination with either coarse spray or gel droplet applications. Together, this work explores the current strategies to prevent coccidiosis, methods to improve the effectiveness of these strategies, and applies new technologies to the diagnostics of Eimeria species infections. en_US
dc.description.sponsorship Ontario Agri-Food Alliance, and NSERC Discovery Grant #400566 en_US
dc.language.iso en en_US
dc.publisher University of Guelph en_US
dc.subject coccidiosis en_US
dc.subject broiler chickens en_US
dc.subject coccidiosis-vaccination en_US
dc.subject anticoccidial medication en_US
dc.subject anticoccidial resistance en_US
dc.subject molecular diagnostics en_US
dc.title Coccidiosis in commercial broiler chickens: Improving management of Eimeria species using live-vaccination or anticoccidial medication and developing and applying quantitative species-specific molecular assays. en_US
dc.type Thesis en_US
dc.degree.programme Pathobiology en_US
dc.degree.name Doctor of Philosophy en_US
dc.degree.department Department of Pathobiology en_US
dc.rights.license All items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
dc.degree.grantor University of Guelph en_US


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