EXAMINATION OF INTERNATIONAL GENETIC EVALUATIONS OF HOLSTEIN BULLS

The first large-scale, international genetic evaluation of Holstein bu lls computed by the International Bull Evaluation Service Centre in Fe bruary 1995 was examined and compared with national evaluations from C anada, Denmark, Finland, France, Germany, Italy, Sweden, The Netherlan ds, and the US. Assumption of a genetic correlation of 0.995 between a ll countries and exclusion of bull daughters from a country in which t he bull had not been sampled resulted in correlations of essentially u nity between national and international evaluations. For the few bulls sampled in multiple countries, correlations were lower but still high (less than or equal to 0.95). Genetic trend was more rapid for countr ies in which genetic merit for earlier years was lowest. Differences a mong countries in genetic merit of recent bulls have decreased markedl y, especially between the US and other countries. Mean evaluation for bulls born during 1988 in the US surpassed means for bulls in France, Italy, and The Netherlands by <3 kg for PTA for protein. Application o f seven national economic indexes showed that some indexes with differ ent mathematical forms can rank bulls similarly. If the official index for one country is assumed to be optimal, use of an index from anothe r country could substantially reduce the mean merit of selected bulls by more than one-half an index standard deviation. Selection on either national or international genetic evaluations can give rapid genetic progress if the economic index is correct.