Theses and Dissertations

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Open Access
Bovine tuberculosis slaughter surveillance in the United States: assessment of its trace-back function 2001-2010
(Colorado State University. Libraries, 2012) Mann, Heather, author; Olea-Popelka, Francisco, advisor; Orloski, Kathleen, committee member; Salman, Mo, committee member; Basaraba, Randall, committee member
The detection of gross bovine tuberculosis (bovine TB) lesions in cattle at slaughter and the successful trace-back to the herd of origin is critical to the detection of infected herds and for the progress of the national bovine TB eradication program in the United States (U.S.). A national animal identification system to identify and trace individual animals is currently under development in the U.S.; however, it is not yet fully implemented. In order to quantify the impact slaughter surveillance and traceability of bovine TB infected cattle has on the eradication of bovine TB from the cattle population in the U.S., this study was conducted with the aim to determine the ability of the current bovine TB slaughter surveillance system to trace infected cattle back to the herd of origin. Data obtained for the period 2001-2010, in which 386 bovine lesions were confirmed as bovine TB in the U.S., were used for this study. The specific objectives for this study were 1) to review and document the available literature related to the history of bovine TB control in the U.S., focusing primarily on the current method of disease detection (slaughter surveillance) and the impediments to eradication in the U.S., 2) to quantify the number of successful trace-backs of bovine TB infected animals to their herd of origin during 2001-2010 3) to quantify the number of trace-backs that found at least one bovine TB infected ("affected") herd, and 4) determine if selected factors were associated with the probability of successfully tracing infected animals and finding infected herds. The results of this study indicates that the odds of successful trace-backs are 7.06 times greater for cattle with official identification than without official identification (OR 95% CI: 1.66, 29.93, p-value =0.008). Additionally, the odds of successful trace-back are 15.47 times greater for adult cattle compared to fed cattle (OR 95% CI: 4.47, 53.48, p-value<0.001). Thus, application of official ID on all classes of cattle would increase the probability of successfully tracing bovine TB cases back to a herd of origin; however, under the current system it will not ensure a complete success in tracing bovine TB infected cattle to the herd of origin. While adult cattle are currently more likely to be traced back than fed cattle, it is worth noting that the effort and time required to find the herd of origin for both adult and fed bovine TB cases can be substantial and is highly variable. The results of this study provide an important tool to aid U.S. officials in their decision making with respect to the evaluation and implementation of strategies for the national bovine TB control and eradication program.
Open Access
Immunoproteomic identification of bovine pericardium xenoantigens
(Colorado State University. Libraries, 2008) Griffiths, Leigh G., author; Orton, E. Christopher, advisor; Reardon, Kenneth F., advisor
Bovine pericardium (BP) is an important biomaterial used in the production of gluteraldehyde-fixed heart valves and tissue engineering applications. The ability to perform proteomic analysis on BP is potentially useful for several reasons including investigation of immune rejection after implantation. The importance of humoral and cell mediated rejection responses towards such xenogeneic tissues are becoming increasingly apparent. I have applied a novel immunoproteomic approach to survey the antigenic determinants of BP. Proteomic analysis of fibrous tissues like BP is challenging due to their relative low cellularity and abundance of extracellular matrix. A variety of methods for tissue homogenization, protein extraction, and fractionation were investigated with the aim of producing high quality 2-DE gels for both water- and lipid-soluble BP proteins. MALDI-TOF/TOF MS protein identifications were performed to confirm bovine origin and appropriate subcellular fractionation of resolved proteins. Sixteen unique predominantly cytoplasmic bovine proteins were identified from the water-soluble gels. Twenty-two unique predominantly membrane bovine proteins were identified from the lipid-soluble gels. These results demonstrate that the final 2-DE protocol produced high quality proteomic data from BP for both cytoplasmic and membrane proteins. Duplicate 2-DE gels were used to generate western blots from both water- and lipid-soluble gels. Western blots were probed with pre- and post-exposure anti-BP rabbit serum, with detection of immune complexes limited to the IgG subtype. Western blots were compared to duplicate 2-DE gels and spots matched using Delta 2D image analysis software. Protein identifications of matched spots were performed using either MALDI-TOF/TOF MS or ESI MS/MS. This approach identified 31 putative antigens, capable of stimulating an IgG humoral rejection response. To the best of my knowledge, this study was the first to apply an immunoproteomic approach for identification of antigenic targets in xenotransplanted tissues. The results provide important information for understanding and possibly mitigating the immune response to fixed and unfixed BP xenografts.
Open Access
Investigation into disease events at the wildlife/livestock interface: lessons learned from bovine viral diarrhea virus in Colorado cervids
(Colorado State University. Libraries, 2009) Duncan, Colleen, author; Salman, Mo, advisor; VanCampen, Hana, advisor
Infectious agents may be transmitted between wild and domestic animals; these so called 'interface diseases' can have significant economic consequences. As such, effective tools and techniques with which to study disease in free ranging, wild animals is essential. Principles of wildlife disease surveillance were reviewed and it was concluded that while wildlife disease research may require unique logistical adaptations; basic principles of surveillance remain the same. A review of wildlife data sources utilized for surveillance suggests that information collected, and shared, is dependent on the group involved and that there are opportunities to improve the type and quality of material available. Bovine viral diarrhea virus (BVDV) is an important virus of domestic cattle that has recently been identified in wild ruminants worldwide. To investigate the presence, prevalence, distribution and significance of BVDV in wild cervids of Colorado a series of projects were conducted. Persistently infected (PI) deer were studied post mortem; immunohistochemical and molecular techniques used to look for viral antigen in deer tissue were found to be effective supporting the use of these tests in further studies. The prevalence and distribution of PI cervids in the state was evaluated using an opportunistic sampling technique; the prevalence is extremely low, but naturally occurring infection is present within Colorado. The cost associated with testing animals for an uncommon disease may be very high; techniques like pooling samples can help to keep costs down during such investigations. The sensitivity and specificity of RT-PCR on pooled samples was investigated in an experimental study and revealed that supernatant from a single positive deer skin sample may be diluted up to 10,000 times and still be detected. Another technique to focus research efforts on high risk areas is the use of simulation modeling. A stochastic risk assessment model was developed to identify regions in Colorado where PI cattle were likely to be born following exposure to a PI deer. Results of the model were consistent with both the cross-sectional survey for PI cervids and other reports on BVDV in wildlife of Colorado.
Open Access
Peri-slaughter ecology of Escherichia coli O157 and Salmonella enterica in feedlot beef cattle
(Colorado State University. Libraries, 2008) Dewell, Grant Alan, author; Salman, Mo, advisor
Risk factors for prevalence of E. coli O157 prior to slaughter and the genotypic relationship between feedlot and slaughter isolates were investigated. The odds of E. coli O157 positive fecal samples from cattle fed brewers grains were 6 times that for cattle not fed brewers grains. The odds of E. coli O157 positive fecal samples from cattle from Central Nebraska was 9 times that for cattle from Eastern Colorado. Within the sampled pens, 64% of the hide samples at the abattoir corresponded to a feedlot isolate. For carcass samples, 59% of isolates had a corresponding feedlot isolate. Transportation of cattle from the feedlot to the slaughter plant could influence hide contamination of Escherichia coli O157 or Salmonella enterica. Cattle held in E. coli O157 positive lairage pens had eight times greater relative risk of having E. coli O157 positive hide samples compared to cattle held in culture-negative pens. Cattle that were held in lairage pens contaminated with feces had three times greater relative risk for E. coli O157 positive hide samples and twice the relative risk for S. enterica positive hide samples compared to cattle held in clean pens. Cattle that were transported for long distances (> 160.9 km) had twice the relative risk of having E. coli O157 positive hide samples and twice the relative risk of having S. enterica positive hide samples compared to cattle transported shorter distances. Cattle with positive Salmonella enterica hide samples at the feedlot had almost twice the relative risk of having S. enterica positive hide samples compared to cattle without S. enterica positive feedlot hide samples. Cattle transported in trailers with positive S. enterica samples had over twice the relative risk of having S. enterica positive hide samples compared to cattle transported in culture negative trailers. Cattle held off feed longer than 18 hours before loading had a greater relative risk of having S. enterica positive hide samples compared to cattle held off feed for shorter times. Cattle that were agitated during loading had twice the relative risk of having S. enterica positive hide samples compared to cattle that were calm.

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Browsing Theses and Dissertations by Subject "animal sciences"

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