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Genetic and Financial Considerations of Progeny Testing Programs in an Artificial Dairy Cattle Population¹

University of Minnesota, St. Paul 55101

ABSTRACT

This study examined several alternatives for increasing rate of selection among progeny tested bulls.

A numerical model was developed to simulate the processes by which population regeneration and improvement are achieved through artificial insemination. The model generated a cow population in which the average age at freshening was 4.7 yr with an average of 3.04 lactations per cow.

Three methods of increasing rate of selection among progeny tested bulls were analyzed genetically and economically. They were:

1. Increasing the fraction of the cow population bred to young bulls from 12% to 35% so a larger number of young bulls could be progeny tested with progeny group size kept constant.
   
2. Decreasing progeny group size from 150 to 50 so a larger number of young bulls could be progeny tested without increasing the fraction of the cow population bred to them.
   
3. Increasing the usage of proven sires from 17,000 inseminations/yr to 43,000 inseminations/yr so fewer of them are needed.
   

For a population similar to this one, the rate of selection among progeny tested bulls could be increased profitably to 1 in 5 by method I and to 1 in 9 by method II. Method III would permit increases in selection at essentially the same cost, and the increase in selection by this method would be limited primarily by the limit on the rate of usage.

¹ Scientific Journal Series Paper No. 8527, Minnesota Agricultural Experiment Station, St. Paul.

² Present address: Dept. of Animal Sciences, Cornell University, Ithaca, N.Y. 14850.