UBC Theses and Dissertations
Dairy cattle transition period : disease prevalence and risk factors in grazing and freestall systems Darós, Rolnei Ruã
Many dairy cows become ill in the weeks after calving. The goal of this thesis was to study the epidemiology of these ‘transition cow’ diseases in pasture and confinement systems by undertaking two large observational studies, one in Santa Catarina, Brazil and another in British Columbia, Canada. There is a dearth of research on the prevalence and incidence of transition period diseases in grazing systems. Using a cross sectional approach we measured the prevalence and risk factors for common transition period diseases in 53 small-scale, year-round, grazing dairy herds in Santa Catarina, Brazil. We found that the prevalence of metabolic and infectious diseases in these herds were comparable to those described on high producing indoor systems. Our findings also identified risk factors associated with transition period diseases in these grazing herds. One highly prevalent challenge in indoor systems is lameness, a malady that is often an overlooked in studies of transition period disease. Through a longitudinal study, we followed 455 dairy cows housed indoors on farms located in the lower Fraser Valley region of British Columbia, Canada, to: 1) measure lameness during the prepartum period and 2) assess how lameness contributes to the development of transition diseases. There was a high incidence of lameness during the non-lactating ‘dry’ period, and cows that were lame during the dry period were more likely to develop transition period diseases. One possible mechanism for this association is via reduced feeding time, as lame cows spent less time feeding than sound cows. Reduced body condition score during the dry period was also associated with increased risk of transition period diseases, independently of lameness and feeding time. I conclude that preventing lameness and body condition loss during the dry period may improve transition health.
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