A survey of Chronic Pneumonia and Polyarthritis Syndrome (CPPS)- associated Mycoplasma bovis in western Canadian feedlots
Whelan , Rose A. K.
Mycoplasma bovis is generally considered the causative pathogen associated with Chronic Pneumonia and Polyarthritis Syndrome (CPPS) in feedlot cattle. However, M. bovis virulence may vary between strains as it is also isolated from asympytomatic cattle. The following study aims to determine the prevalence of M. bovis in the respiratory tract of western Canadian cattle using two sampling methods and at two time points following feedlot entry. Three study groups were sampled. In the first group nasal swabs (NS) and bronchoalveolar lavages (BAL) were taken from 36 clincally healthy cattle at the University of Saskatchewan feedlot at both 14 and 90 days on feed (DOF). In a second experiment, NS were taken from 56 animals upon arrival at a commercial feedlot and one week to three months later upon treatment for respiratory disease. Lung and joint tissue swabs were collected at necropsy from a third group of 19 animals with CPPS clinical pathology originating in 10 different western Canadian feedlots. All samples were selectively cultured for Mycoplasma spp. DNA was extracted from isolated putative Mycoplasma colonies and amplified with universal 16S rRNA gene primers for identification. Amplified Fragment Length Polymorphism (AFLP) was used to genetically differentiate M. bovis positive isolates. More M. bovis was isolated from NS than BAL and M. bovis prevalence increased with DOF in the feedlot in both the University of Saskatchewan and commercial feedlot trials. Three genetically distinct clusters (A, B, and C) were isolated from the necropsy group. Two of these clusters were primarily associated with isolates collected from feedlot cattle and one strain was exclusively found in CPPS-associated mortalities. No significance difference in the prevalence of M. bovis strains was observed between different days on feed or sampling methods. It was concluded that either the difference in disease state is a host dependent outcome, due to a multi-factorial disease complex, or the AFLP assay was not sensitive enough to differentiate strains based on virulence.
DegreeMaster of Science (M.Sc.)
DepartmentAnimal and Poultry Science
ProgramAnimal and Poultry Science
SupervisorVan Kessel, Andrew
CommitteeLaarveld, Bernard; Chirino, Manuel; McKinnon, John; Jelinski, Murray; Perez-Casal, Jose
Copyright DateMay 2010