DEPENDENT-VARIABLES IN INTERNATIONAL SIRE EVALUATIONS

Stochastic simulation was used to assess the suitability of alternativ e dependent variables in international sire evaluation, Three such var iables were considered: daughter yield deviations (DYD), national proo fs (ETA), and de-regressed national proofs (DPRF). Data from two dairy cattle populations considering 10 generations were simulated. Genetic ties necessary for a joint evaluation of the two populations were est ablished with bull exchange in each generation. De-regressed national proofs were the best and ETA were the worst in estimating genetic diff erence between the two populations and ranking bulls across country. F urther, de-regressed national proofs can be easily computed and, contr ary to DYD, are always available. De-regressed national proofs are rec ommended as dependent variables in across country sire evaluation.