title: Multiple-trait prediction of lactation yields for dairy cows.
abstract: A multiple-trait procedure is described for predicting 305-d lactation yields for milk, fat, and protein that incorporates information about standard lactation curves and covariances between yields for milk, fat, and protein. Test day yields are weighted by their relative variances, and standard lactation curves of cows from similar breed, region, lactation number, age, and season of calving are used for the estimation of lactation curve parameters for each cow. Accuracies of the test interval method and the multiple-trait procedure were comparable. In addition, the multiple-trait procedure can handle long intervals between test days as well as test days with milk only recorded and can make 305-d predictions on the basis of just one test day record per cow. The procedure also lends itself to the calculation of peak yield, day of peak yield, yield persistency, and expected test-day yields, which could be useful management tools for a producer on a milk recording program.
authors.affiliation: Department of Animal and Poultry Science, University of Guelph, ON, Canada.
authors.forename: L R
authors.initials: LR
authors.lastname: Schaeffer
authors.forename: J
authors.initials: J
authors.lastname: Jamrozik
mesh_terms: D000818:Animals; D002417:Cattle / Q000235:genetics / Q000502:physiology*; D005260:Female; D007774:Lactation / Q000235:genetics / Q000502:physiology*; D008055:Lipids / Q000032:analysis; D008433:Mathematics; D008892:Milk / Q000737:chemistry; D008894:Milk Proteins / Q000032:analysis; D008954:Models, Biological; D010641:Phenotype; D013997:Time Factors
chemical_list: D008055:Lipids; D008894:Milk Proteins