Browsing by Author "Schuster, Jessica Claire"
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Item Open Access Longevity in Canadian Dairy Cows(2020-01-15) Schuster, Jessica Claire; Orsel, Karin; Barkema, Herman W.; Kelton, David F.A thorough review of longevity in dairy cows was conducted to evaluate current understanding of longevity. Current terminology referring to longevity is inconsistent; therefore, standardized definitions are needed. Longevity is affected by genetics, environment and management impacts, along with culling decisions for genetic improvement. Therefore, this thesis proposes that producers aim to optimize longevity by ensuring a favourable environment via optimal management, providing each cow an opportunity to reach her full genetic potential. An evaluation of animal-level variables was conducted to identify intrinsic factors affecting longevity. Additionally, an economic evaluation that assessed individual impact of each of these variables on lifetime profitability was estimated. Reproductive performance had the greatest impact on estimated culling time and profitability in young-stock and cows, suggesting performance indicators (e.g. milk production, reproduction, health and young-stock performance) should be incorporated into farm level evaluations of longevity to enable producers to make evidence-based decisions for optimizing longevity.