Multibreed Sire Evaluation Procedures within a Country

Abstract

Summary Frequently, exotic, hybrid and native sires are evaluated based on progeny records, using additive models for direct effects and assuming common genetic variances across breed groups. In some cases, however, additive maternal and nonadditive direct and maternal fixed and random effects may be important. Also, heterogeneous variances across genetic groups may exist. Hence, sire proofs from additive models will be biased and not of minimum variance. Sire-maternal grandsire models that account for direct and maternal, additive and nonadditive fixed and random effects as well as different additive and nonadditive variances across genetic groups are presented. Direct and maternal effects are treated as separate characters. Sire proofs for direct and maternal traits contain group (fixed) and sire (random) additive and nonadditive effects. Problems of confounding and multicollinearity may arise due to empty cells in the design. Ridge regression may be used to help remove problems of multicollinearity. Extension to multitrait evaluation is straightforward.