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Expansion of projected lactation records to stabilize genetic variance



Expansion of projected lactation records to stabilize genetic variance



Journal of Dairy Science 73(Supplement 1): 143



For USDA-DHIA genetic evaluations, projected and completed lactation records are modelled as having equal genetic variance. Current projection procedures use information from the partial record, last sample day and herd mean. Regressing the estimate toward herd mean causes projected records to have less phenotypic and genetic variance than do 305-day records. Degree of reduction in variance and possible methods of correction were investigated.

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Accession: 001831305

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