Components of Variance Associated with Milk and Fat Records of Artificially Sired Holstein Daughters

Components of variance are estimated for the three-way classification analysis of variance of DHIA reported first and second milk and fat records of artificially sired Holstein cows and of Owner-Sampler reported milk and fat records of artificially sired Holstein cows. The total variance of milk and fat records is partitioned into the following components with the approximate percent of total variance: sire, 6%; year-season, 2%; herd, 30%; sire by year-season, 0%; sire by herd, 1–2%; herd by year-season, 6–8%; sire by herd by year-season, 1–7%; and residual, 50%. Copyright © 1961 American Society of Animal Science. Used by permission. C O M P O N E N T S O F V A R I A N C E A S S O C I A T E D W I T H M I L K A N D F A T R E C O R D S O F A R T I F I C I A L L Y S I R E D H O L S T E I N D A U G H T E R S L. D. VANVLECK, L. H. WADELL, AND C. R. HENDERSON Cornell University, Ithaca, New York C OMPONENTS of variance have been used widely in genetic and animal breeding applications. Some earlier reports of these techniques were by Lush et al. (1934), Bywaters (1937), Stonaker and Lush (1942), and Baker et al. (1943). Important animal breeding applications of variance component estimates are: (1) to predict the breeding values of sires or dams and to predict real producing abilities of cows, (2) to indicate sources of variation which should be considered in analyzing production records, (3) to aid in the establishment of progeny testing programs, including design of the test, number of progeny required, and effectiveness of such programs, and (4) to direct attention to sources of genetic by genetic, genetic by environmental, and environmental by environmental interactions which should be considered in the above programs. The purpose of this paper is to present estimates of sire, herd, year-season, and interaction components of variance for first and second milk and fat DHIA records and OwnerSampler milk and fat records of artificially sired (AI) Holstein daughters.