Journal article

A computationally feasible test day model for genetic evaluation of yield traits in the United States

GR Wiggans, ME Goddard

Journal of Dairy Science | AMER DAIRY SCIENCE ASSOC | Published : 1997


A multitrait analysis of test day yields is proposed that includes 60 traits [3 yield traits (milk, fat, and protein), 2 parity groups (first and later) per yield trait, and 10 stages of lactation per parity]. To reduce the computations needed for the 60 traits, test day effects are estimated within the herd before analysis across herds, the rank of t he genetic (co)variance matrix is reduced, a canonical transformation is used with missing values replace by their expectations, and a repeatability model is applied to allow inclusion of parities after second. Historical 305-d records are included through their correlations with test day effects. Possible benefits from this model include 1) mo..

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University of Melbourne Researchers