An exploration of ecological concepts in the context of antimicrobial resistance and the use of phytochemical compounds within the ruminant gut microbiome

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dc.contributor.supervisor Holley, Rick (Food Science) en_US
dc.contributor.author Knox, Natalie
dc.date.accessioned 2013-01-05T15:54:47Z
dc.date.available 2013-01-05T15:54:47Z
dc.date.issued 2011-02 en_US
dc.date.issued 2008-12 en_US
dc.identifier.citation Berard, N. C., Wang, Y., Wittenberg, K. M., Krause, D. O., Coulman, B. E., McAllister, T. A. and Ominski, K. H. 2011. Condensed tannin concentrations found in vegetative and mature forage legumes grown in western Canada. Can J Plant Sci 91: 669-675. en_US
dc.identifier.citation Berard, N. C., Holley, R. A., McAllister, T. A., Ominski, K. H., Wittenberg, K. M., Bouchard, K. S., Bouchard, J. J. and Krause, D. O. 2009. Potential to reduce Escherichia coli shedding in cattle feces by using sainfoin (Onobrychis viciifolia) forage, tested in vitro and in vivo. Appl Environ Microbiol 75: 1074-1079. en_US
dc.identifier.uri http://hdl.handle.net/1993/14405
dc.description.abstract Secondary plant metabolites have recently been gaining interest in livestock production systems following the ban of in-feed antibiotics within the European Union. The rise in antimicrobial resistance found in pathogenic and non-pathogenic bacteria has lead to increased interest in the research community regarding the use of phythochemicals as an alternative to antibiotics. The purpose of this research was to evaluate the impact of including phytochemicals in a livestock production system. Specifically, a high tannin-containing forage, sainfoin (Onobrychis viciifolia), was evaluated in vitro for its antimicrobial effect on Escherichia coli. We determined that phytochemicals alone are not as inhibitory as synthetic antibiotics. Thus, the use of combination therapy to deter the development of antimicrobial resistance was evaluated. A myriad of plant compounds were screened for their synergistic interactions with ciprofloxacin. Geraniol, an essential oil, was identified to possess good antimicrobial activity and synergistic interactions with ciprofloxacin. Therefore the effect of long term exposure to both ciprofloxacin and geraniol were examined. Results demonstrated that once an antimicrobial concentration threshold was reached, resistance to ciprofloxacin increased markedly in the presence of both geraniol and ciprofloxacin. Finally, an in vivo trial was conducted in which forty steers were fed sainfoin or alfalfa over a 9-week period to evaluate its ability to reduce E. coli shedding and its impact on gut microbiota in the context of popular theoretical ecology concepts. Results from the in vivo study indicate that sainfoin was able to promote a slight decrease in generic E. coli shedding which could be maintained throughout the trial. Using high-throughput sequencing, the effect of sainfoin on the microbial ecosystem of the ruminant gut was evaluated. Sainfoin induced a significant shift in the microbial community structure of the rumen and to a lesser extent in the hindgut. Using ecology theories, a hypothesis was formulated regarding the mechanisms that mediate the development of tolerance and the fundamental ecological processes controlling microbial population shifts. Understanding how the gut ecosystem functions and predicting its behaviour in the presence of various fluctuating environmental conditions will enable more efficient manipulation of the rumen and promote best management practices in livestock production. en_US
dc.publisher Agricultural Institute of Canada, publisher of Canadian Journal of Plant Science en_US
dc.publisher American Society for Microbiology en_US
dc.rights info:eu-repo/semantics/openAccess
dc.subject antibiotic resistance en_US
dc.subject ruminant gut microbiome en_US
dc.subject phytochemicals en_US
dc.subject microbial ecology en_US
dc.subject condensed tannins en_US
dc.title An exploration of ecological concepts in the context of antimicrobial resistance and the use of phytochemical compounds within the ruminant gut microbiome en_US
dc.type info:eu-repo/semantics/doctoralThesis
dc.type doctoral thesis en_US
dc.degree.discipline Animal Science en_US
dc.contributor.examiningcommittee Ominski, Kim (Animal Science) Wittenberg, Karin (Animal Science) McAllister, Tim (Animal Science) Zhanel, George (Medical Microbiology) Morrison, Mark (Queensland University) en_US
dc.degree.level Doctor of Philosophy (Ph.D.) en_US
dc.description.note February 2013 en_US

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