Thesis (M.P.H.)--University of Texas Health Science Center at Houston, School of Public Health, 2008. / Source: Masters Abstracts International, Volume: 46-06, page: 3219. Adviser: Herbert L. DuPont. Includes bibliographical references

No description available.

The determination of dietary habits by examination of fresh stomach, intestinal or faecal material is widely used in vertebrate and invertebrate ecology. Generally speaking, most fresh faecal studies depend upon microscopic determinations of the ingested material. One of the more recent applications includes microscopic studies of the grazing habits of sheep. [...]

M. Phil. in Marine Environmental Science. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1967. / eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Jianfa Bai / Cattle feces are a major source of six Shiga toxin-producing E. coli (STEC) serogroups, O26, O45, O103, O111, O121, and O145, called non-O157 STEC, responsible for >70% of non-O157 STEC-associated human illnesses. Another E. coli serotype, O104:H4, a hybrid pathotype of enteroaggregative and STEC, was responsible for a large outbreak of foodborne illness in Germany. Studies were conducted to develop and validate culture- and PCR-based methods to detect and or quantify six non-O157 E. coli serogroups and E. coli O104 in cattle feces, and genetically assess their virulence potential, based on DNA microarray and whole genome sequencing (WGS). Two multiplex quantitative PCR (mqPCR) assays (assay 1: O26, O103 and O111; assay 2: O45, O121 and O145), targeting serogroup-specific genes, were developed and validated for the detection and quantification of six non-O157 E. coli in cattle feces and was compared to culture-based and end-point PCR methods. The mqPCR assays detected higher proportion of fecal samples as positive for one or more non-O157 E. coli serogroups compared to culture-based and end-point PCR methods. Spiral plating method was validated to quantify six non-O157 E. coli serogroups in cattle feces, and was compared to mqPCR assays. The mqPCR assays quantified higher proportion of fecal samples positive for one or more non-O157 E. coli serogroups compared to spiral plating method, however, unlike mqPCR, spiral plating method quantifies serogroups positive for virulence genes. Quantification by either mqPCR or spiral plating identified a subset of cattle that was shedding non-O157 E. coli at high concentrations (≥ 4 log CFU/g of feces), similar to E. coli O157. Identification of Shiga toxin subtypes associated with non-O157 E. coli serogroups isolated from cattle feces revealed a variety of subtypes, with stx1a and stx2a being the most predominant. Microarray-based analysis of six non-O157 E. coli serogroups isolated from cattle feces revealed the presence of stx, LEE-encoded, and other virulence genes associated with human illnesses. Analysis of WGS of STEC O145 strains isolated from cattle feces, hide and human clinical cases revealed similarity in virulence gene profiles, suggesting the potential of cattle E. coli O145 strains to cause human illnesses. Shiga toxin 1a was the most common stx subtype, followed by stx2a, and stx2c. The strains also carried LEE-encoded, and plasmid-encoded virulence genes. Model adjusted prevalence estimates of E. coli O104 in cattle fecal samples collected from feedlots (n=29) were 0.5% and 25.9% by culture and PCR methods, respectively. Cattle harbor O104 serotypes other than H4, with O104:H7 being the predominant serotype and only a small proportion of them carried stx. DNA microarray and WGS analysis revealed absence of LEE-encoded virulence genes in bovine and human O104 strains. Escherichia coli O104:H7 has the potential to be a diarrheagenic foodborne pathogen in humans, since they possess stx1c and genes that code for enterohemolysin and a variety of adhesins. Data on prevalence, concentration and virulence potential of non-O157 E. coli serogroups, including O104, isolated from cattle feces are essential to design effective intervention strategies to reduce the potential to cause human foodborne illness outbreaks.

No description available.

Two studies were performed to investigate the ability of a portable near-infrared spectrophotometer (NIRS) for on-site analysis of nutrient components in feces from cattle. In trial 1 of study 1, growing dairy steers were fed diets containing either 86 or 90% concentrate. Regression values from a calibration set of 56 samples were promising for CP, DM, and NDF, but not for ADF or starch. In trial 2 of study 1, finishing dairy steers were fed diets containing either thick (512 g/L) or thin (460 g/L) steam-flaked corn. Regression values from a calibration set of 126 samples were poor for all nutrients. Both studies showed statistically valid NIRS calibrations, but further validation was required to make regression values acceptable (R² > 0.80) for all fecal nutrient components. In study 2, NIRS analysis was employed on novel research. Young dairy bull calves were fed diets containing either whole or steam-flaked corn from pre-weaning until 8 weeks post-weaning when the first animal was heavy enough for inclusion into a commercial feedlot. Again, although statistically valid, regression values from a calibration set of 220 samples were promising for CP and ADF, but not predictive for DM, NDF, ash, and starch. Growth performance parameters were similar between diets, with starch digestibilities diverging after weaning and changing to a Holstein starter diet. These 2 studies show that commercial and research application of a portable NIRS for on-site analysis of the nutrient composition of feces from young, growing, and finishing dairy steers statistically possible but requires further validation research. Also, results from the second study imply that there is no advantage in feeding steam-flaked corn to dairy calves from pre-weaning to 8 weeks post-weaning or until reaching feedlot weight. However, starch digestibility begins to improve for steam-flaked corn to whole corn once the animal has been weaned.

Thesis (M.S.)--Michigan State University. Comparative Medicine and Integrative Biology, 2006. / Title from PDF t.p. (viewed on Nov. 20, 2008) Includes bibliographical references (p. 94-102). Also issued in print.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Tiruvoor G. Nagaraja / Cattle are a reservoir for major Shiga toxin-producing Escherichia coli (STEC), which includes STEC O157 and the top six non-O157 serogroups (STEC-6; O26, O45, O103, O111, O121, O145). Collectively known as the STEC-7, these organisms are harbored in the hindgut and shed in the feces of cattle, which can contaminate hides. The de-hiding step during beef cattle processing can introduce fecal contaminants from the hide onto the carcass surface, creating the potential for contaminated beef products. The STEC-7 have been declared by the USDA-Food Safety and Inspection Service as adulterants in ground beef and non-intact beef products, and are monitored during beef cattle processing. However, many of the culture- and PCR-based tests for detection and/or quantification of the STEC, particularly of the STEC-6, are not established or require improvement and also virulence characteristics of STEC strains from cattle have not been fully analyzed. Therefore, the following studies were conducted: 1. Immunomagnetic separation (IMS)-based culture-method for detection of STEC-6 in cattle feces was developed and compared to a PCR-based method; 2. Detection sensitivity of pooled vs. individual IMS beads for isolation STEC-6 from cattle feces was evaluated; 3. Real-time PCR assay, based on the clustered regularly interspaced short palindromic repeat sequence polymorphisms (CRISPR), was developed and validated for serotype-specific detection and quantification of STEC O157:H7 in cattle feces; 4. Virulence gene profiles of bovine enterohemorrhagic (EHEC), enteropathogenic (EPEC) and putative non-pathotype E. coli O103 strains were examined with whole genome sequence (WGS)-based comparative analysis; 5. Prevalence and concentration of STEC-7 of fed-beef, cull beef and cull dairy cattle were determined. The culture and PCR methods detected all six serogroups in samples negative by the other method. Based on noninferiority tests, detection with pooled IMS beads was not inferior to detection with individual beads. Detection limits of the CRISPR-based qPCR assay for cattle feces spiked with pure cultures were 2.1 x 10³ and 2.3 x 10⁰ colony-forming units/g before and after enrichment, respectively. WGS-based analysis of E. coli O103 strains revealed key differences in the virulomes and mobilomes of EHEC, EPEC, and putative non-pathotype strains. The prevalence study revealed that a significantly higher (P < 0.01) proportion of hide samples from fed beef cattle (4.8%) were positive for STEC O157:H7, compared to samples from cull beef (1.6%) or cull dairy (0.2%); the majority of quantifiable STEC O157:H7 from each cattle type was at concentrations between 3 to 4 log CFU/100 cm². These data contribute to a knowledge gap on prevalence and concentration of STEC-7 and surrogate bacteria on cattle hides and carcasses, respectively. Furthermore, the development and refinement of culture- and PCR-based screening assays may lead to increased surveillance of major STEC serogroups, especially if the potential of WGS-based comparative genomics in identifying novel gene targets can be harnessed.