Abstract
Pedigree and performance data supplied by seven major artificial insemination (AI) studs were examined to evaluate the intensity of pedigree and progeny test selection achieved in choosing young Holstein bulls for future use in AI. The bulls and cows chosen to produce sons for sampling represented a group of individuals highly selected for milk and milk fat production and for type traits; pedigree selection, however, was less effective than expected. Selection indexes computed in retrospect for the sires and dams of young bulls revealed a general overemphasis of milk fat production and classification score relative to milk production for the combinations of economic, genetic, and phenotypic parameters.As a group, the studs returned to service approximately 25% of sons sampled. The mean performance of sons returned to service exceeded the mean performance of all sons sampled by 146.2kg and 5.0kg for regressed deviated milk and milk fat yield and 2.2 points for classification score. Genetic progress per year might be considerably reduced by an excessively long generation interval.
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