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Journal of Dairy Science Vol. 55 No. 11 1621-1630
© 1972 by American Dairy Science Association ®
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Selection of Holstein Bulls for Future Use in Artificial Insemination1

W. E. Vinson2 and A. E. Freeman

Department of Animal Science, Iowa State University, Ames 50010

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 146.2 kg and 5.0 kg 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.

FOOTNOTES

1 Journal Paper J-7174 of the Iowa Agriculture and Home Economics Experiment Station, Ames, Iowa. Project 1053 as a collaborator under the North Central Regional Project, NC-2, Improvement of Dairy Cattle Through Breeding.

2 Present Address: Department of Dairy Science, Virginia Polytechnic Institute and State University, Blacksburg 24061.






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Copyright © 1972 by the American Dairy Science Association ®.