The objectives of this thesis were to investigate 1) the use of behavior and activity monitoring for the identification of heifers at risk of disease, 2) the use of group level management practices to reduce the risk of disease, and 3) the identification of long-term impacts of bovine respiratory disease complex (BRD). For objective 1, lying posture, a decreased willingness to approach an observer and high lethargy scores were associated with diarrhea in calves under 2 weeks of age and a high lethargy score in 4-6 week old calves was associated with decreased average daily gain (ADG) in the first 8 weeks of life (n = 744). In weaned calves (n = 74) increased activity (increase in steps and decrease in lying), standing at the bunk not eating, and lying far from other calves in the first 3 days post-weaning were associated with decreased post-weaning weight gain. For objective 2, separating social mixing from movement to a novel environment, and administering prophylactic antibiotics to calves at high risk of disease, were investigated. Both mixing and movement to a novel environment increased activity levels in newly weaned dairy calves (n = 64). When calves were mixed prior to movement to a novel environment they had a smaller increase in activity compared to calves that were simultaneously mixed and moved. No differences in weight gain or calf starter intake were observed. Administration of a prophylactic antibiotic, tulathromycin, to 3 day old calves upon arrival at a heifer raising facility (n = 788) and 8 week old calves at first movement to group housing (n = 1,392 ) was found to reduce diarrhea and otitis media, and BRD, respectively. Objective 3 was addressed by monitoring calves that received tulathromycin at 8 weeks of age to determine the long-term impacts of BRD. Bovine Respiratory Disease complex was associated with decreased growth to 9 months of age, decreased survival to first calving, increased risk of dystocia and a greater age at first calving. / Natural Sciences and Engineering Research Council of Canada & Pfizer Animal Health

Pneumonic pasteurellosis is a significant disease in beef production medicine. The most recent information suggests that this disease is a $700 million dollar per year economic burden in bovine food animal production The medical and pathological characteristics of this disease are well documented. Many pathological findings associated with pneumonic pasteurellosis may be explained by disruption of the pulmonary vascular adrenergic system. However, only a limited amount of research has addressed the adrenergic system and its relationship to the etiology and pathophysiology of this disease. In an attempt to further investigate the contributions of the vascular adrenergic receptor mechanism to the development of pneumonic pasteurellosis a series of six experiments have been completed. It is to be noted, that in 1999 the organism Pasteurella haemolytica was renamed Mannheimia haemolytica. The name change was based on the taxonomic features of the organism from other closely related organisms, in particular Pasteurella multocida.. The differences noted were identified and described by Dr. Mannheim in 1974. The familiarity of the past nomenclature and the lack of familiarity for the new nomenclature suggests that the more commonly recognized name of Pasteurella haemolytica should be used throughout this document. Scientific evidence suggests that the disruption of the normal homeostatic mechanisms of the pulmonary vasculature to beta adrenergic agents may be part of the etiology of pneumonic pasteurellosis. The dynamics and kinetics of the involvement of the beta receptors, following prophylactic vaccination and in the disease state, has yet to be fully investigated with respect to the events associated with pneumonic pasteurellosis. Evaluation of the time frame of the onset and duration of the events associated with the disruption of pulmonary vascular beta adrenergic receptor mechanisms revealed that an escalating level of dysfunction occurs over the first 24-48 hour period after exposure to parenteral Pasteurella haemolytica and lasts for at least 21 days. A component of P.haemolytica organism or contained in the vaccine using the organism is likely associated with the disruption of vascular beta adrenergic mechanism. This factor is, as yet, not specifically identified, however the likely culprit is the lipid A moiety of the endotoxin. Using the well defined and purified Escherichia coli endotoxin, trials were run to examine the effect of endotoxin on the pharmacological response of vascular associated beta adrenergic receptor mechanisms. The effects of Escherichia coli endotoxin, administered parenterally, on beta adrenergic receptor mechanisms were pharmacologically indistinguishable from those effects following parenterally administered Pasteurella haemolytica. The nature of the disruption in the beta adrenergic receptor remains a mystery. The receptor mechanism involves at least two second messengers to initiate vascular relaxation. Initial activation of the beta adrenergic receptor with a beta selective drug starts a cascade of events involving adenylylate cyclase and cyclic adenylylate monophosphate (cAMP) and nitric oxide. A disruption in the receptor mechanism, as a result of the parenteral administration of Pasteurella haemolytica, which is "upstream" of adenylyl cyclase, would result in a diminished amount of cAMP when compared to the unvaccinated negative controls. An investigation of cAMP accumulation, at the receptor level was inconclusive. The assessment of some previously used vaccines has demonstrated that there is an, as yet unidentified virulence factor, associated with these vaccines that results in the pharmacological disruption of beta adrenergic receptor mechanisms. Two newer vaccines, Once PMH® and One Shot® have been evaluated and there is evidence to suggest that these currently used vaccines also have the ability to disrupt beta adrenergic receptor mechanisms in rats. The effects of parenteral P. haemolytica on the alpha-2 adrenergic receptor mechanism, is described. The alpha-2 receptor mechanism, unlike the beta receptor mechanism appears to increase the amount of vasoconstriction. The possibility that the alpha-2 adrenergic receptor could also mediate vasorelaxation under certain conditions was investigated. The evidence suggests that in the presence of high alpha-1 mediated vascular tone, the alpha -2 receptor can cause vasorelaxation. Evidence, from other scientists active in this area of investigation, suggests that a vasorelaxation response may be mediated by nitric oxide. Elimination of the nitric oxide mediated relaxation may offer an explanation for the increased vasoconstriction noted with alpha-2 selective drugs after exposure to parenteral P. haemolytica. Finally, the importance of the beta adrenergic receptor to the disease process is addressed by elucidation of one of the mechanisms by which Micotil 300® (tilmicosin phosphate) acts to improve cattle with symptomatic pneumonic pasteurellosis. The rapid improvement of animals on Micotil 300®, with-in 24 hours suggests that there is a mechanism beyond the antimicrobial effect of the drug that mediates the clinical improvement. Evaluation of the effect of Micotil 300® demonstrates a pharmacologically measurable amount of beta adrenergic activity with respect to the bovine pulmonary artery and vein. Based on the conclusions drawn as a result of these experiments, the adrenergic system in general, and the beta adrenergic system in particular are important to the development of pneumonic pasteurellosis in cattle. The beta adrenergic system is affected by endotoxin. Further, these receptors maybe responsible for the mediation of the pathological and clinical signs associated with pneumonic pasteurellosis. In conclusion, these investigations have suggested, that it is likely that a disruption in the homeostatic mechanisms mediated by the beta and alpha-2 adrenergic receptors are intimately involved in the development of post vaccination receptor failure as well as the pathophysiology associated with pneumonic pasteurellosis in cattle. / Ph. D.

Doctor of Philosophy / Department of Diagnostic Medicine/Pathobiology / Robert L. Larson / Bradley J. White / There are multiple modalities available to evaluate health or stress status of animals. The objective of my research was to evaluate different modalities including behavior, rectal and nasal temperature, and blood samples to determine the relationship with these outcomes of interest in bovine respiratory disease (BRD) events, environmental conditions, transportation, and Mannheimia haemolytica challenge model. The objective for the final project was to determine whether diagnostic sensitivity or specificity resulted in greater economic value for the industry using simulation models for identification of BRD. There was a positive association with rectal temperature and probability of not finishing the production cycle normally, but this relationship was not linear. Rectal temperature of feedlot calves at first treatment for BRD had limited value as a prognostic indicator of whether those calves would finish the production cycle normally. A positive association between rectal temperature and ambient temperature and temperature-humidity index was determined. Environmental conditions must be considered when rectal temperature is used as a diagnostic tool. At 48 hours after initiation of transportation there were no differences in body weight, rectal temperature, and time spent at various locations in the pen detected between transported and non-transported control heifers. Transportation of heifers during periods of high ambient temperatures caused transient changes in physiologic and behavioral indices of heifers. Calves challenged with Mannheimia haemolytica had more changes in behavior, body weight, and blood biomarkers during high ambient temperatures compared to control calves. Results of this study may guide research in development of objective assessment tools for identification and management of cattle affected with BRD during extreme summer conditions. For both low and high apparent prevalence cohorts, increasing diagnostic specificity resulted in more rapid, positive change in net returns compared to change in increasing sensitivity. Improvement of diagnostic specificity, perhaps through a confirmatory test or pen-level diagnostics, can increase diagnostic value. Mortality risk was the primary driver for net returns. Results from this study are important for determining future research priorities to analyze diagnostic techniques for BRD and provide a novel way for modeling diagnostic tests.

O complexo respiratório bovino é um dos principais problemas encontrados em bovinos tanto confinados quanto àqueles criados a pasto, levando a importantes perdas econômicas devido aos altos índices de morbidade e mortalidade. O objetivo geral deste trabalho foi determinar a prevalência de M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida, M. haemolytica, Parainfluenza Bovino tipo-3 (PIb- 3) e Influenza vírus D e a prevalência de anticorpos contra Vírus da Diarreia Viral Bovina (VDVB), Herpesvírus tipo -1 (BoHV1) e o Vírus Respiratório Sincicial Bovino (VRSB) em bezerros sadios e com broncopneumonia criados nos assentamentos de Caiuá, Presidente Epitácio e Mirante de Paranapanema - SP. Além disso, objetivase avaliar a associação destes micro-organismos com a presença da broncopneumonia e dos sinais e sintomas apresentados pelos animais durante a avaliação física. Estudou-se 141 bezerros, machos e fêmeas de até um ano de idade, os quais, após exame físico, foram classificados em sadios e com pneumonia. Foram coletadas amostras de lavado traqueobrônquico e sangue total para obtenção do soro. As amostras foram utilizadas para isolamento e identificação de M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida e M. haemolytica, detecção molecular de Parainfluenza Bovino tipo-3 (PIb-3) e Influenza vírus D (IVD) e detecção de anticorpos contra Vírus da Diarreia Viral Bovina (VDVB), Herpesvírus tipo -1 (HVBo-1) e o Vírus Respiratório Sincicial Bovino (VRSB). Não houve isolamento de P. multocida e M. haemolytica. Dentre as bactérias aeróbias isoladas, observou-se maior frequência de isolamento de Bacillus sp., Staphylococcus intermedius e bactérias Gram-negativas não fermentadoras. M. díspar foi a única espécie de micoplasma identificada com os oligonucleotídeos iniciadores utilizados. Faz-se necessário a busca por outras espécies de micoplasmas que podem estar relacionadas aos casos de broncopneumonia em bovinos. Não houve detecção de Parainfluenza Bovino tipo 3 e Influenza vírus D nas amostras de lavado traqueobrônquico. Os três municípios estudados apresentaram anticorpos para os vírus estudados. Observou-se prevalência de BoHV-1, VDVB e VRSB de 31,7%, 24,6 e 38,8%, respectivamente. Não houve associação entre o status de saúde dos bezerros e os achados microbiológicos e sorológicos. Foi observada associação entre enterobactérias e a variável “desidratação leve” (p=0,033/ OR= 11,25, IC: 1,809-41,834. Observou-se associações entre Mollicutes e a variável “secreção nasal serosa” (p=0,03). Concluiu-se que a broncopneumonia é uma enfermidade multifatorial. Faz-se, necessário, portanto, a associação dos achados de exames físico, microbiológicos e características do ambiente e manejo / Bovine respiratory disease complex is one of the major problems observed in feedlot and grazing cattle, causing economic losses due to high morbidity and mortality rates. The aim of this study was to determine the prevalence of M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida, M. haemolytica, Bovine Parainfluenza type-3 (bPI-3) and Influenza vírus D (IVD) and the prevalence of antibodies against Bovine Viral Diarrhea Vírus (BVDV), Bovine Herpesvírus type -1 (BoHV1) and Bovine Respiratory Syncytial Vírus (VRSB) in healthy and pneumonic calves raised in settlements located in Caiuá, Presidente Epitácio e Mirante de Paranapanema São Paulo State. Moreover, we aimed to evaluate the association between those microorganisms and antibodies and the presence of bronchopneumonia and the symptoms observed during the physical examination. We studied 141 males and females calves that were classified as healthy and pneumonic calves. We collected tracheobronchial lavage samples and total blood to obtain serum samples. Isolation and biochemical/ molecular identification were performed in order to detect M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida, M. haemolytica, Bovine Parainfluenza type-3 and Influenzavírus D. Serological survey was performed to detect antibodies aginst Bovine Viral Diarrhea Vírus (BVDV), Bovine Herpesvírus type -1 (BoHV1) and Bovine Respiratory Syncytial Vírus (VRSB). There was not any isolation of P. multocida and M. haemolytica. Bacillus sp., Staphylococcus intermedius and Non-fermenter Gram-negative bacteria were higher prevalent compared to the other aerobic bacteria isolated. M. díspar was the only mycoplasma species identified by the primers used. It is necessary the identification of other mycoplasma species that could be related to the cases of bronchopneumonia in cattle. Bovine Parainfluenza type-3 and Influenza vírus D were not identified. Antibodies were detected in all municipalities. The prevalence of BoHV, BVDV e VRSB was 31.7%, 24.6 and 38.8%, respectively. The association between health status and microbial/ serological findings was not observed. Enterobacterias were associated to “mild dehydration” (p=0.033/OR=11.25; IC: 1.809-41.834). Associations between Mollicutes and “serous nasal discharge” (p=0.03) was also detected. In conclusion, S. intermedius was associated to “nasal air flow” (p=0.097). In conclusion bovine bronchopneumonia is multi-factorial disease. It is necessary, though, physical examination, microbiology and management and environment feature results

O complexo respiratório bovino é um dos principais problemas encontrados em bovinos tanto confinados quanto àqueles criados a pasto, levando a importantes perdas econômicas devido aos altos índices de morbidade e mortalidade. O objetivo geral deste trabalho foi determinar a prevalência de M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida, M. haemolytica, Parainfluenza Bovino tipo-3 (PIb- 3) e Influenza vírus D e a prevalência de anticorpos contra Vírus da Diarreia Viral Bovina (VDVB), Herpesvírus tipo -1 (BoHV1) e o Vírus Respiratório Sincicial Bovino (VRSB) em bezerros sadios e com broncopneumonia criados nos assentamentos de Caiuá, Presidente Epitácio e Mirante de Paranapanema - SP. Além disso, objetivase avaliar a associação destes micro-organismos com a presença da broncopneumonia e dos sinais e sintomas apresentados pelos animais durante a avaliação física. Estudou-se 141 bezerros, machos e fêmeas de até um ano de idade, os quais, após exame físico, foram classificados em sadios e com pneumonia. Foram coletadas amostras de lavado traqueobrônquico e sangue total para obtenção do soro. As amostras foram utilizadas para isolamento e identificação de M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida e M. haemolytica, detecção molecular de Parainfluenza Bovino tipo-3 (PIb-3) e Influenza vírus D (IVD) e detecção de anticorpos contra Vírus da Diarreia Viral Bovina (VDVB), Herpesvírus tipo -1 (HVBo-1) e o Vírus Respiratório Sincicial Bovino (VRSB). Não houve isolamento de P. multocida e M. haemolytica. Dentre as bactérias aeróbias isoladas, observou-se maior frequência de isolamento de Bacillus sp., Staphylococcus intermedius e bactérias Gram-negativas não fermentadoras. M. díspar foi a única espécie de micoplasma identificada com os oligonucleotídeos iniciadores utilizados. Faz-se necessário a busca por outras espécies de micoplasmas que podem estar relacionadas aos casos de broncopneumonia em bovinos. Não houve detecção de Parainfluenza Bovino tipo 3 e Influenza vírus D nas amostras de lavado traqueobrônquico. Os três municípios estudados apresentaram anticorpos para os vírus estudados. Observou-se prevalência de BoHV-1, VDVB e VRSB de 31,7%, 24,6 e 38,8%, respectivamente. Não houve associação entre o status de saúde dos bezerros e os achados microbiológicos e sorológicos. Foi observada associação entre enterobactérias e a variável “desidratação leve” (p=0,033/ OR= 11,25, IC: 1,809-41,834. Observou-se associações entre Mollicutes e a variável “secreção nasal serosa” (p=0,03). Concluiu-se que a broncopneumonia é uma enfermidade multifatorial. Faz-se, necessário, portanto, a associação dos achados de exames físico, microbiológicos e características do ambiente e manejo / Bovine respiratory disease complex is one of the major problems observed in feedlot and grazing cattle, causing economic losses due to high morbidity and mortality rates. The aim of this study was to determine the prevalence of M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida, M. haemolytica, Bovine Parainfluenza type-3 (bPI-3) and Influenza vírus D (IVD) and the prevalence of antibodies against Bovine Viral Diarrhea Vírus (BVDV), Bovine Herpesvírus type -1 (BoHV1) and Bovine Respiratory Syncytial Vírus (VRSB) in healthy and pneumonic calves raised in settlements located in Caiuá, Presidente Epitácio e Mirante de Paranapanema São Paulo State. Moreover, we aimed to evaluate the association between those microorganisms and antibodies and the presence of bronchopneumonia and the symptoms observed during the physical examination. We studied 141 males and females calves that were classified as healthy and pneumonic calves. We collected tracheobronchial lavage samples and total blood to obtain serum samples. Isolation and biochemical/ molecular identification were performed in order to detect M. bovis, M. díspar, M. mycoides subsp. mycoides SC, P. multocida, M. haemolytica, Bovine Parainfluenza type-3 and Influenzavírus D. Serological survey was performed to detect antibodies aginst Bovine Viral Diarrhea Vírus (BVDV), Bovine Herpesvírus type -1 (BoHV1) and Bovine Respiratory Syncytial Vírus (VRSB). There was not any isolation of P. multocida and M. haemolytica. Bacillus sp., Staphylococcus intermedius and Non-fermenter Gram-negative bacteria were higher prevalent compared to the other aerobic bacteria isolated. M. díspar was the only mycoplasma species identified by the primers used. It is necessary the identification of other mycoplasma species that could be related to the cases of bronchopneumonia in cattle. Bovine Parainfluenza type-3 and Influenza vírus D were not identified. Antibodies were detected in all municipalities. The prevalence of BoHV, BVDV e VRSB was 31.7%, 24.6 and 38.8%, respectively. The association between health status and microbial/ serological findings was not observed. Enterobacterias were associated to “mild dehydration” (p=0.033/OR=11.25; IC: 1.809-41.834). Associations between Mollicutes and “serous nasal discharge” (p=0.03) was also detected. In conclusion, S. intermedius was associated to “nasal air flow” (p=0.097). In conclusion bovine bronchopneumonia is multi-factorial disease. It is necessary, though, physical examination, microbiology and management and environment feature results