The purpose of this work was to examine the effectiveness of several replacements for antibiotics in broiler chickens using bacterial challenge models. For this work, pathogen challenge models were developed using three model pathogens; two human pathogens (<i>Salmonella enteritidis</i> and <i>Campylobacter jejuni</i>), and one poultry pathogen (<i>Clostridium perfringens</i>). The first set of experiments involved the selection and use of 2 model probiotics; <i>Bifidobacterium animalis</i> and <i>Lactobacillus fermentum</i>. Oral administration of either probiotic did not significantly reduce (P < 0.05) the level of intestinal colonization by either <i>S. enteritidis</i> or <i>C. jejuni</i> in experimentally infected broiler chickens. The next set of experiments examined the effectiveness of orally administered, pathogen-specific antibodies obtained from hyperimmunizing laying hens in controlling bacterial infections with <i>S. enteritidis</i>, <i>C. jejuni</i> or <i>Clostridium perfringens</i> in broiler chickens. Regardless of the concentration, or mode of administration, anti-<i>S. enteritidis</i> hen-egg antibodies or anti-<i>C. jejuni</i> hen-egg antibodies were unable to significantly reduce (P < 0.05) the intestinal colonization by either pathogen in experimentally infected broiler chickens. Likewise, administration of anti-<i>C. perfringens</i> hen-egg antibodies did not reduce intestinal colonization by <i>C. perfringens</i>, and actually exacerbated the clinical outcome of this important poultry pathogen by significantly increasing (P < 0.05) intestinal lesions scores compared to negative control birds. Lastly, the effect of dietary protein source on intestinal <i>C. perfringens</i> populations was investigated. In broiler chickens experimentally infected with <i>C. perfringens</i> and fed diets which varied in the source of dietary protein, it was shown that birds fed fish meal, meat/bone meal, feather meal and potato protein concentrate had significantly higher intestinal <i>C. perfringens</i> counts than the birds fed corn gluten meal, soy or pea protein concentrates or the control diet (P < 0.05). Further, it was shown that the glycine content of the diets and ileal contents was significantly, positively correlated with <i>C. perfringens</i> numbers in ileum and cecum. It is concluded that although the intervention strategies employed in these studies show promise, diet composition clearly had the largest effect on intestinal bacterial populations. Further studies are required to examine both the impact that diet and these intervention strategies have on the factors which control intestinal colonization by pathogens on a case by case basis.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:SSU.etd-03312006-134440 |
| Date | 03 April 2006 |
| Creators | Wilkie, Darryl Clayton |
| Contributors | Laarveld, Bernard, Drew, Murray D., Classen, Henry L. (Hank), Chirino-Trejo, Manuel, Buchanan, Fiona C., Van Kessel, Andrew G. |
| Publisher | University of Saskatchewan |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | http://library.usask.ca/theses/available/etd-03312006-134440/ |
| Rights | unrestricted, I hereby certify that, if appropriate, I have obtained and attached hereto a written permission statement from the owner(s) of each third party copyrighted matter to be included in my thesis, dissertation, or project report, allowing distribution as specified below. I certify that the version I submitted is the same as that approved by my advisory committee. I hereby grant to University of Saskatchewan or its agents the non-exclusive license to archive and make accessible, under the conditions specified below, my thesis, dissertation, or project report in whole or in part in all forms of media, now or hereafter known. I retain all other ownership rights to the copyright of the thesis, dissertation or project report. I also retain the right to use in future works (such as articles or books) all or part of this thesis, dissertation, or project report. |
Page generated in 0.0059 seconds