The impact of unrecorded culling of first lactation daughters on sire genetic evaluations for production traits

dc.contributor.advisorRobinson, Andy
dc.contributor.authorAnsell, Jennifer Lynn
dc.date.accessioned2020-08-24T15:44:09Z
dc.date.available2020-08-24T15:44:09Z
dc.date.copyright2003
dc.degree.departmentDepartment of Animal and Poultry Scienceen_US
dc.degree.grantorUniversity of Guelphen_US
dc.degree.nameMaster of Scienceen_US
dc.description.abstractThe impact of unrecorded culling (URC) of first lactation daughters, prior to receiving an official test day record, on the integrity of sire genetic evaluations for production traits was investigated. Simulation was used to generate a complete set of realistic production records with full pedigree. Ten or twenty percent of the sires in the population were randomly chosen to be affected by 2%, 5%, 10% or 20% URC of the phenotypically worst daughters based on mean test day milk yield. Bias in EBV for milk yield, and correlated traits fat yield and protein yield, increased proportionately as culling intensity increased (5-48%). Sires re-ranked significantly for all traits at all culling percentages. The prominent re-ranking of elite sires under high URC levels could result in the loss of genetic improvement, while re-ranking under low to moderate URC levels were negligible. Results showed that low to moderate levels of unrecorded culling were not a practical concern for genetic evaluations in this study.en_US
dc.identifier.urihttps://hdl.handle.net/10214/19765
dc.language.isoen
dc.publisherUniversity of Guelphen_US
dc.rights.licenseAll items in the Atrium are protected by copyright with all rights reserved unless otherwise indicated.
dc.subjectUnrecorded cullingen_US
dc.subjectDairy Cattleen_US
dc.subjectFirst lactation daughtersen_US
dc.subjectSire genetic evaluationsen_US
dc.subjectProduction traitsen_US
dc.titleThe impact of unrecorded culling of first lactation daughters on sire genetic evaluations for production traitsen_US
dc.typeThesisen_US

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