Progeny-Tests of Sire and Son

Abstract

The general method of progeny-testing dairy sires by contemporary comparisons is summarized. The efficiency of the method is measured by the correlation between the sire''s true genetic merit and his merit as estimated from the progeny test; it depends on the number of daughters available. The expression for the correlation is manipulated to provide a procedure for calculating the number of daughters required in a progeny-test in order that the correlation between estimated and true merit of a sire shall be of predetermined magnitude. A son''s merit can be estimated from his sire''s progeny and from his own. Relationships between these estimates and the sire''s progeny-test are discussed, one conclusion being that for a heritability of 0.25, a sire''s progeny-test based on an infinite number of daughters gives no more information about his son''s true merit than does a progeny-test of the son himself based on 5 of his own daughters.