Browsing by Author "Van Metre, David C., committee member"
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Item Open Access Antimicrobial resistance surveillance in feedlot cattle(Colorado State University. Libraries, 2011) Benedict, Katharine M., author; Morley, Paul S., advisor; Booker, Calvin W., committee member; Van Metre, David C., committee member; Basaraba, Randall J., committee memberObjectives: To develop and validate methodological components of a model for surveillance of antimicrobial use and resistance in feedlot cattle. Methods: A web-based survey of participants knowledgeable and interested in antimicrobial use in beef feedlots was used to solicit responses regarding appropriate metrics for quantifying, analyzing, and reporting antimicrobial exposures. The accuracies of two susceptibility tests commonly recommended for surveillance programs were determined using stochastic latent class analysis. Multivariable logistic and linear regression was used to investigate associations between exposures to antimicrobial drugs and antimicrobial resistance. Results: When reporting antimicrobial use in the context of antimicrobial resistance, survey participants believed that the Animal Defined Daily Dose metric was the most accurate. The two susceptibility tests investigated had comparable accuracies for the antimicrobial drugs tested. Exposure to parenteral tetracycline in the study feedlots was associated with resistance to tetracycline; however, exposures to all other classes of antimicrobials were not associated with antimicrobial resistance. Conclusions: Appropriate metrics for reporting and analyzing antimicrobial resistance are necessary to accurately investigate associations between use and resistance, though clarity of what the metric represents may be lost. Testing of susceptibility in surveillance programs is equally valid by way of disk diffusion testing. Multivariable logistic regression was an appropriate and useful method to investigate associations between use and resistance. Parenteral exposures to antimicrobials did not drive antimicrobial resistance at mid-feeding period.Item Open Access Interaction of copper source, bile composition on microbial growth, and Cu protein homeostasis(Colorado State University. Libraries, 2011) Arnold, Mark Alan, author; Engle, Terry E., advisor; Wagner, John J., committee member; Van Metre, David C., committee memberOne hundred twenty weaned nursery pigs (6.12 ± 0.56 kg) were utilized in this experiment to determine the effects of Cu concentration and source on performance, bile components, Cu metabolism, and gastrointestinal microbial distribution in nursery pigs blocked by weight and gender and placed in pens containing 5 pigs of similar weight distribution per pen. Pigs were fed one of four dietary treatments for 21 or 22d. Treatments consisted of: 1) Control (5 mg of Cu/kg from CuSO 4); 2) 250 mg of Cu/kg from CuSO 4, (250-sulfate) 3) 75 mg of Cu/kg from Cu-MINTREX®Cu (75-Min; Novus International, Inc., St. Charles, MO), and 4) 75 mg of Cu/kg from CuSO4 (75-sulfate). On d 22 and 23, equal numbers of pigs per treatment were slaughtered. Post slaughter, blood, liver, intestinal tissue and contents, and bile samples were obtained. Body weights, ADG, and ADFI were similar across treatments (P > 0.20). Feed efficiency was greater (P < 0.05) for pigs receiving 250-sulfate compared to controls (0.53 vs. 0.43 ± 0.03, respectively), and pigs fed 75-Min (0.47 ± 0.03) or 75-sulfate (0.44 ± 0.03) were intermediate. Pigs receiving 250-sulfate had greater (P < 0.05) bile (7.05 vs. 2.06 ± 0.49; respectively) and liver (124.4 vs. 53.3. ± 24.6, respectively) Cu concentrations than controls. Bile components, intestinal bacterial populations, and small intestine gene expression profiles (Ctr-1, Atox-1, Cox-17, ATP7a, and ATP7b) associated with Cu absorption and homeostasis were similar across treatments (P > 0.20). Antimicrobial effects of bile (determined by measuring the diameter of the zone of inhibition; mm) tended (P < 0.20) to be higher for 250-sulfate and 75-Min treatments compared to controls. Data from this experiment indicated that Cu dose influenced pig performance, but dose or source did not influence measured bile components, intestinal bacterial populations, or intestinal gene expression profiles associated with Cu absorption.Item Open Access Nosocomial infection rates in veterinary referral hospitals: using syndromic surveillance to establish baseline rates(Colorado State University. Libraries, 2011) Ruple-Czerniak, Audrey, author; Morley, Paul S., advisor; Lunn, Katharine F., committee member; Peel, Jennifer L., committee member; Van Metre, David C., committee memberNosocomial, or hospital-acquired, infections are considered to be the most common complication affecting hospitalized human patients, but their impact on hospitalized veterinary patients is less well understood. In fact, the incidence of nosocomial infections that occur in veterinary hospitals has not been established. There is evidence, however, that nosocomial infections are of great consequence in veterinary medicine and can have considerable negative effects on the individual patient as well as on the veterinary hospital as a whole. Due to the increased risk of infection in hospitalized patients, it is anticipated that some nosocomial infections will occur. Establishing a baseline rate of infection using surveillance techniques will allow investigators to ascertain the proportion of infections that can be prevented using infection control measures. The purpose of this study was to establish baseline rates of infection using a syndromic surveillance system created for implementation in small animal and equine referral hospitals. This study included weaned dogs, cats, and horses (n=2248) that were hospitalized in the critical care unit of one of five participating veterinary hospitals during a 12 week period in 2006. Clinicians actively performed syndromic surveillance on hospitalized patients and reported their results no later than the time of the patient’s discharge from the hospital. Adjusted rates of nosocomial events were estimated using Poisson regression, and risk factors associated with an increased risk of developing a nosocomial event were analyzed using multivariable logistic regression. Adjusting for hospital of admission, 19.7% of horses, 16.3% of dogs, and 12% of cats included in this study were reported to have experienced a nosocomial event occur during hospitalization. The only risk factor found to have a positive association with the development of a nosocomial event in all three species was placement of a urinary catheter. Surgical site inflammation and intravenous catheter site inflammation were two of the most commonly reported events across all species. Results of this study suggest that nosocomial event rates can be established using syndromic surveillance systems in multiple hospitals. Data pertinent to risk factors for the occurrence of nosocomial events can also be effectively collected using the same technique. Further research is warranted in order to evaluate how generalizable these results are to other veterinary healthcare settings.Item Open Access Prevalence and risk factors associated with bluetongue virus among Colorado sheep flocks(Colorado State University. Libraries, 2010) Mayo, Christie Ellen, author; Hill, Ashley E., advisor; Bowen, Richard A., committee member; Van Metre, David C., committee member; Callan, Robert J., committee memberTo view the abstract, please see the full text of the document.Item Open Access Silvopastoral system for sustainable cattle production in the tropics of Mexico(Colorado State University. Libraries, 2017) Erales Villamil, José Alberto, author; Salman, Mo, advisor; Reid, Robin S., committee member; Solorio Sánchez, Francisco J., committee member; Van Metre, David C., committee member; Zepeda, Cristobal, committee memberTraditional production system has exhausted natural resources and depleted soil nutrients reducing farm productivity and forcing farmers to expand farm lands, which, increases deforestation and pollution. Global warming and an increasing global population pose additional strain to the already fragile global food security, making it urgent for innovative production systems to be developed. Such systems, adapted to local circumstances and designed to reduce deforestation and increase food production, must emerge to provide an expanding global food demand while enabling preservation of natural resources. In Mexico, a five-year research project, derived from a national initiative has proposed a silvopastoral model for the Tepalcatepec valley, in the State of Michoacan, as an alternative to conventional livestock ranching in the tropics. The primary objective for this research project was to characterize the advantages and disadvantages of an alternative livestock farming model, the silvopastoral system. One hundred and fifteen farmers in the Tepalcatepec valley were surveyed to characterize their farms, their family demographics, main cattle breed, crops farmed, cattle diet, measures of animal performance (productivity) commercialization (marketing practices) and animal health management practices. An analysis of the progress of the various national SPS initiatives was also performed in order to identify gaps in research, collaboration, stakeholder education, and application of SPS farming in Mexico. A systems analysis was conducted on the research project using the information compiled from the team of scientists surveyed. Components related to carbon capture, biodiversity, soil quality, nutrient recycling, and larger-scale cycles such as water cycle need to be incorporated into future research. An accurate measure of the true economic and ecological impact of SPS farming is an essential goal. Improved communication among scientists, government agencies, and stakeholders is also essential for successful research into SPS farming. The animal health component of the five-year Mexican national SPS project is the focus of this dissertation. Traditional livestock health practices on participating small farms were characterized, and common health problems of cattle were identified. A community based livestock syndromic surveillance system was developed, implemented, and observed for two years on five selected farms. Observations from farmers and veterinarians were triangulated to validate data on animal health collected by laypeople. For each farm under study, monthly cumulative incidence per animal category (calf, grower or adult), the most frequent disease syndrome, and the syndrome that carried the greatest economic impact were calculated. Most Rho correlation coefficients for farmer's and veterinarian's observations were high. Farmers that implemented the silvopastoral model were considered typical of those who practiced this farming method elsewhere within the region. Because participating farms shared production system, husbandry, livestock health status, disease preventive measures, products, and commercialization channels, they were considered an epidemiological compartment for quantitative risk analysis. Six different scenarios were created and analyzed using the software @Risk™ to measure the risk of introduction of bovine tuberculosis into this epidemiological compartment. The Mexican national program for control and eradication of bovine tuberculosis norm, regional prevalence on bovine tuberculosis, and current cultural practices in Tepalcatepec valley were considered for this analysis. The introduction of replacement heifers or sires into the farms, and the probability of the introduction of at least one infected animal was estimated. The least probable scenario for the introduction of tuberculosis into this compartment was the introduction of at least one infected animal, despite the prevalence of source herd, after applying tuberculin caudal fold test and cervical comparative test in parallel. Although some farmers are aware that the silvopastoral system is profitable, environmental friendly, and socially acceptable, initial investment appears to be the first barrier for adoption. Alternatives for funding SPS development are needed such as preferable interest rates, credit, and loans; notably, an accurate assessment of the costs for establishment of SPS should be more thoroughly studied. The initial three years of SPS implementation have the highest amount on investment; for those years, special attention should be placed on recording the contributions of timber and/or fruit to financial returns, since these products may be the key for offsetting the cost of SPS implementation Further research is needed to more accurately measure the economic, ecological, animal health, and human health impact of the silvopastoral model of farming in the tropics. An ample variety of species combinations, suitable for silvopastoral production, should be studied and different arrays proposed to encourage scaling up the model. Research funding is scarce; however, public awareness of the need for a change in production practices and the allure of environmental friendly-produced animal products can produce a market-driven change in these small-scale food production operations. This could engender greater research support from industry and government sources, as well as non-governmental organizations dedicated to promoting sustainable agricultural practices in a changing global environment.Item Open Access The development and characterization of caprine infection models of melioidosis(Colorado State University. Libraries, 2012) Soffler, Carl, author; Bowen, Richard A., advisor; Aboellail, Tawfik A., committee member; Dow, Steven S., committee member; Schweizer, Herbert P., committee member; Van Metre, David C., committee memberMelioidosis, the disease resulting from infection with Burkholderia pseudomallei, is a serious emerging infectious disease endemic to Southeast Asia and Northern Australasia and a leading infectious cause of death in the former. Additionally, B. pseudomallei has been designated a Category B Select Agent by the United States Centers for Disease Control and Prevention because of its potential use in bioterrorism, which has led to intensive research on inhalational models of murine melioidosis. Natural infection is believed to occur predominantly through percutaneous inoculation or inhalation in the rainy season in endemic areas, with infection following oral exposure occurring to a lesser extent. However, the actual importance of each route of infection in natural disease is unknown. Studies examining the comparative pathogenesis of melioidosis in regards to the route of infection are generally lacking, particularly in naturally affected species. A goat model was selected as it provides the opportunity to study the importance of the route of infection and its effect on disease pathogenesis in a naturally affected species. Disease and outcome can be evaluated relative to natural presentations in both human and goat populations as goats and humans exhibit a similar epizootiology/epidemiology of melioidosis, which corresponds to similar environmental exposure to B. pseudomallei within its endemic range. Furthermore, the larger body size of goats allows for human-relevant clinical monitoring as well as longer-term serial evaluation of disease progression and therapy in individual animals. Using a caprine model system, we have investigated the pathogenesis of infection following intratracheal aerosol and percutaneous exposure to 104 delivered colony forming units (CFU) of B. pseudomallei. Disease was observed in all animals following infection. Acute disease was more severe in aerosol infected goats, but both groups tended to develop subacute to chronic active disease, with percutaneously infected goats showing regression of lesions at the later time points. Percutaneously infected goats generally exhibited more variable clinical signs, hematologic changes, and gross pathology, but often had histologic lesions with more severe changes. Dissemination from the site of infection was much more rapid in the percutaneously infected animals, with bacteria detectable in the lungs and spleen as early as Day 2 post-infection (PI) and gross abscessation evident in distant sites as early as Day 7 PI. Extrapulmonary dissemination after aerosol infection appeared to occur around Day 7 with splenic or renal abscesses not grossly detectable until day 14. Lesion development was closely associated with a leukocytoclastic vasculitis observed in affected tissues in both aerosol and percutaneous infection. Pulmonary involvement was evident in all but one percutaneously infected goat (Day 2 PI) by culture or the presence of histologic lesions. The rapid dissemination of B. pseudomallei after percutaneous inoculation challenges the perception that inhalational melioidosis is more severe in presentation or will affect the lungs more frequently than percutaneous infection. The findings presented here provide a detailed clinical, radiographic, and pathologic description of the pathogenesis of subacute to chronic aerosol and percutaneous caprine melioidosis. However, acute presentations are possible in association with concurrent disease or debility, suggesting that the caprine model system may be amenable to the incorporation of risk factors to increase susceptibility/acute disease as typically seen in human melioidosis. It is hoped these models will help broaden the scope of melioidosis research to fill remaining voids, particularly in the areas immunology, vaccine development, and evaluation of novel antimicrobial therapeutics through the comparative study of disease. Additionally, melioidosis in goats remains a current problem in the regions of Southeast Asia and Northern Australia with enzootic and epizootic disease causing economic losses. Any knowledge gained from the use of these models in regards to improved diagnosis, preventive measures, and vaccination could be directly applicable to the management of these goat populations and advancing public health.Item Open Access The effect of feed additive program in steam-flaked corn diets containing wet distiller's grains on performance and carcass merit in yearling feedlot steers(Colorado State University. Libraries, 2011) Domby, Elizabeth Marie, author; Wagner, John J., advisor; Engle, Terry E., advisor; Van Metre, David C., committee memberCrossbred yearling steers (432, BW = 329 ± 10.5 kg) were used in an unbalanced randomized block design to examine the effect of feed additives on performance and carcass merit. Treatment factors were arranged as a 2 x 2 factorial and included ionophore and antibiotic [Rumensin/Tylan (R/T) or Cattlyst/Aureomycin (C/A)] and dietary S (constant or variable). High S diets were fed on random days to the variable (VAR) treatment. Low S diets were fed to the VAR treatment on remaining days and to the constant (CON) treatment all days. From d 0 through 35, the high S diet was achieved by using a high S granular supplement; however, since S concentration in wet distillers grains (WDG) is associated with distillers solubles (DS) added to WDG and H2SO4 added to the DS, the high S diet was achieved from d 36 through 159 by using a DS based liquid supplement with 2.35% S while the low S diet was achieved using a 0.99% S DS based liquid supplement. Cause of cattle death for study steers was verified by necropsy. No interaction between S and additive treatments existed for feedlot performance; therefore, only main effects are presented. Most of the sulfur comparisons from this study will be addressed in another manuscript. Feedlot performance and carcass merit were similar for feed additive treatments. The S by feed additive interaction was significant (P < 0.05) for dressing percentage indicating that S treatment had no effect on dressing percentage if R/T was fed but when steers were fed C/A, dressing percentage was reduced by 0.72% (P < 0.02) if VAR diets were fed. The results of this study indicate that performance and carcass characteristics for cattle fed Cattlyst and Aureomycin are similar to performance and carcass characteristics for cattle fed Rumensin and Tylan.