Selection of Holstein Bulls for Future Use in Artificial Insemination

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Abstract
Pedigree and performance data sup- plied by seven major artificial insemina- tion (AI) studs were examined to evalu- ate 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 in- dividuals highly selected for milk and milk fat production and for type traits; edigree selection, however, was less ef- ctive 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 pro- duction for the combinations of eco- nomic, genetic, and phenotypic parame- ters, As a group, the studs returned to service approximately 25% of sons sam- pled. The mean performance of sons re- turned to service exceeded the mean performance of all sons sampled by 146.2 kg and 5.0 kg for regressed devi- ated milk and milk fat yield and 2.2 points for classification score. Genetic progress per year might be considerably reduced by an excessively long genera- tion interval.
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