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dc.contributor.advisorCampbell, Johnen_US
dc.creatorDouma, Dale Peteren_US
dc.date.accessioned2011-03-31T11:49:13Zen_US
dc.date.accessioned2013-01-04T04:27:57Z
dc.date.available2012-04-14T08:00:00Zen_US
dc.date.available2013-01-04T04:27:57Z
dc.date.created2010-12en_US
dc.date.issued2010-12en_US
dc.date.submittedDecember 2010en_US
dc.identifier.urihttp://hdl.handle.net/10388/etd-03312011-114913en_US
dc.description.abstractThis thesis summarizes an investigation of Mycobacterium avium subspecies paratuberculosis (Map) as a pathogen within the cow-calf industry in Canada. The specific objectives of this project were to describe the distribution of this pathogen in this industry provincially, as well as at the individual farm level in wildlife species, and in the environment. Secondary objectives of this project were to identify on-farm management risk factors that are associated with this disease and to examine potential options for herd level diagnostic capabilities. Nationally, 0.8% (95%CI = 0.4-1.1%) of the cows in the cow-calf industry were seropositive for Map with 11.7% (95%CI=7.0-16.5%) of the herds sampled having a minimum of one positive test result or 4.5% (95%CI=1.4-7.5%) of the herds having a minimum of two positive test results. The true cow prevalence was estimated as 1.8% (95%CI= 0.4 – 3.1). No Map was detected in any of the non-ruminant wildlife species sampled on cow-calf operations suggesting that these species were not of primary concern when dealing with the management of this disease. In a study not focussed on a cow-calf operation, Map was detected in one cluster of trapped coyote samples in a region with cow-calf production. The prevalence of Map infection in this cluster of coyotes was calculated to be 9.1% (CI: 5.7-12.5). The prevalence of infection in coyotes including all sites, ignoring the effect of clustering, was calculated to be 3.7% (CI: 2.3-5.1). The use of a commercial colostrum replacement on farm (Odds Ratio =3.96; 95% CI = 1.10–14.23, p=0.035) and the presence of wild deer interacting with the cattle (Odds Ratio = 14.32; 95% CI = 1.13–181.90, p=0.040) were positively associated with being a herd infected with paratuberculosis. The use of rotational grazing practices was protective (Odds Ratio = 0.20; 95% CI = 0.04–0.93, p=0.039). It was possible to detect environmental contamination with Map on cow-calf farms using bacterial culture and PCR for confirmation. No water samples were positive to Map; however, 6.2% of the non-water environmental samples were positive. The use of an environmental sampling protocol had a herd sensitivity of 29.6%. This finding led to a simulation modelling study to evaluate how various testing methods would compare in the broader population of cow-calf herds. The final mean risk of selecting a herd infected with Map that was not identified as positive via the herd screen test strategy was 12.9%, 9.8%, 9.6%, and 6.1% for no herd screen test, environmental sampling, ELISA serology, and pooled fecal culture strategies, respectively.en_US
dc.language.isoen_USen_US
dc.subjectJohne'sen_US
dc.subjectbeefen_US
dc.subjectenvironmenten_US
dc.subjectwildlifeen_US
dc.subjectmanagementen_US
dc.subjectrisk analysisen_US
dc.titleInvestigation of the distribution and risk factors associated with Mycobacterium avium subspecies paratuberculosis in cow-calf herds in Canadaen_US
thesis.degree.departmentLarge Animal Clinical Sciencesen_US
thesis.degree.disciplineLarge Animal Clinical Sciencesen_US
thesis.degree.grantorUniversity of Saskatchewanen_US
thesis.degree.levelDoctoralen_US
thesis.degree.nameDoctor of Philosophy (Ph.D.)en_US
dc.type.materialtexten_US
dc.type.genreThesisen_US
dc.contributor.committeeMemberStookey, Josephen_US
dc.contributor.committeeMemberVanLeeuwen, Johnen_US
dc.contributor.committeeMemberHendrick, Steveen_US
dc.contributor.committeeMemberWaldner, Cherylen_US
dc.contributor.committeeMemberWobeser, Garyen_US


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