Costs and Risks for Sire Selection Strategies in Artificial Insemination

Strategies for selecting sires for artificial insemination involve costs and risks. Costs were related closely to number of young bulls tested. Risk was defined as the standard deviation of Predicted Differences of bulls selected on pedigree for yield. Goals to obtain 25 sires varied in average Predicted Differences for milk. Young bulls were chosen for progeny testing at varying transmitting abilities estimated from pedigree. Also, various Repeatabilities were considered. Results were in three-dimensional graphs. With increasing selection intensity of progeny tested bulls, more bulls needed to be tested, which meant higher costs but less risk. Decreasing accuracy of estimation of Predicted Differences (i.e., reducing Repeatability) gave smaller variance of the estimated Predicted Differences of tested bulls and, therefore, higher selection intensities. Thus, more bulls needed to be sampled at lower risk when Repeatability was low. No objectively determined selection strategy was optimum, because costs and risks were weighted differently and subjectively by individuals making decisions.