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Associations between Canadian Holstein Dairy Cattle Health and Production Traits

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Title: Associations between Canadian Holstein Dairy Cattle Health and Production Traits
Author: Weller, Denise
Department: Department of Animal and Poultry Science
Program: Animal and Poultry Science
Advisor: Schaeffer, Larry
Abstract: A multiple trait, random regression, test day (TD) model was used to determine the heritability and genetic correlations of milk, fat, protein, and SCS with metritis, cystic ovary disease, mastitis, lameness, ketosis, milk fever, and displaced abomasum for four periods in lactations 1, 2, and 3-5 using two disease definitions. Definition 1 assumed that the first disease occurrence affects all TD thereafter equally and definition 2 assumed that disease affects only the next TD. Results were similar between definitions. The models were modified to allow the estimation of differences in disease occurrence by level of production, and to estimate production differences between diseased and non-diseased cows. Few significant associations were found between production levels and disease occurrence, the largest was between MAST and SCS. Diseased animals had lower levels of production than healthy animals for all diseases except COD. Animals with MAST had increased SCS.
URI: http://hdl.handle.net/10214/5204
Date: 2012-12


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