Expected Economic Responses to Selection for Direct and Fetal Genetic Effects

Expected responses in direct and fetal genetic values due to selection of heifers or bulls were computed for various combinations of heritabilities of direct and fetal effects, genetic correlations, economic weights, and kinds of relatives\u27 records. If the economic weights are 1:3 for direct and fetal effects, then records of mates of the sire should be used for selection of both heifers and bulls for the heritabilities .16 to .32. If the economic weights are 1:1, use of records of the mates does not appear important for selection of bulls or heifers. Reliable estimates of genetic covariance and variances of direct and fetal genetic effects are required to decide whether fetal effects need to be considered in selection programs