Despite their beneficial effects, concerns have been raised about the role of antimicrobial
growth promoters (AGP) in the emergence of antibiotic resistant bacteria. This study
evaluated the effects of approved AGP on the emergence of antibiotic resistance in
commensal E. coli and foodborne pathogen Salmonella. A survey of antibiotic resistance
levels in commercial broiler chicken farms in the Fraser Valley (B.C.) and an
experimental feeding trial were conducted from May 2004 to February 2005 and May to
November 2005, respectively. The latter examined the effects of ten AGP formulations
(bambermycin, penicillin, salinomycin, bacitracin, combination of salinomycin and
bacitracin, chlortetracycline, virginiamycin 11ppm, virginiamycin 22ppm, monensin and
narasin) on bird performance as well.
Multiple antibiotic resistant commensal E. coli and Salmonella carrying virulence genes
were found at commercial broiler chicken farms and therefore may serve as reservoirs for these genes. There was no significant difference between feed formulations on the
phenotypic or genotypic characteristics of the isolates, except for tetracycline resistance gene tet(B).
In the experimental feeding trial, broiler chickens were fed a diet including or excluding AGP. Birds were sampled prior to and weekly during feeding of the control and the AGPP containing diets. Although not detected on day 0, E. coli increased after day 7 to more than 9.9 log10 CFU/g in ceca. Multi-drug resistant E. coli were isolated from birds fed the ten AGP containing diets as well as the control diet. Except for penicillin, none of the AGP containing diets significantly improved bird performance compared to the control diet (P>0.05). Good management practices can significantly improve broiler chickens performance and decrease the mortality rate.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:BVAU.2429/1614 |
| Date | 05 1900 |
| Creators | Fatoumata , Diarrassouba |
| Publisher | University of British Columbia |
| 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 | Electronic Thesis or Dissertation |
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