Joint estimation of variances and effects in the US Jersey type evaluation system

A strategy for multitrait genetic evaluation of US Jersey type traits that integrates an accounting for heterogeneous (co) variances was developed. The proposed method allows joint estimation of variances and effects. The new model is theoretically better than the current one and should give less biased rankings of animals, especially for cows. The heterogeneous variance adjustment reduced standard deviations and linear regression coefficients of sampling variances on time substantially. Mendelian sampling variances for 1997 animals with and without adjustments were nearly identical.