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An Analysis of the Relationships Among Stayability, Production, and Type in Canadian Milk-Recording Programs

Department of Animal and Poultry Science, University of Guelph, Guelph, Ontario, Canada

ABSTRACT

Sire proofs for stayability to 17, 30, 43, and 55 mo of productive life were related to official production and type proofs in three milk-recording programs: 1) Ontario and Quebec Record of Performance, 2) supervised Ontario Dairy Herd Improvement and Quebec Dairy Herd Analysis Service, and 3) owner-sampler Dairy Herd Analysis Service. Simple correlations among all stayability traits and most production and type traits were significant and positive for the Record of Performance data set. Milk, fat yield, and a few type traits were positively correlated with stayability to 17 and 30 mo of productive life for the supervised data set. Only milk and fat yield had significant relationships with early stayability for the owner-sampler data. Highest multiple squared correlations in the Record of Performance analyses resulted when milk yield, final class or general appearance, and rump were included in the regression equations. For the supervised analyses, multiple squared correlation was highest when dairy character and feet and legs or mammary system were included in the prediction of stayability to 17 and 30 mo and when mammary system alone predicted stayability to 43 mo. For the owner-sampler analyses, only fat yield was included when predicting stayability to 17 and 30 mo.