Standards and Procedures for International Genetic Evaluations of Dairy Cattle

Abstract

Increased international trade with frozen semen and embryos has greatly underlined the necessity to extend evaluations of genetic material beyond their original areas of use. Problem areas in evaluations of sire proofs across countries are briefly discussed and include the effects of different ways of expressing genetic merit, level of production, choice of base for evaluation, data for analyses, and variable reliability of proofs. Recent results from conversion of North American Holstein sire proofs into European Friesian populations are reviewed. Generally agreement has been good between converted proofs and the original ones of the native countries provided these were reasonably accurately estimated. A simulation study performed within the framework of INTERBULL concluded that estimates of intercepts and regressions for a formula proposed by the International Dairy Federation for conversion of sire proofs were accurate when deregressed proofs of the importing country were used for analysis. Future considerations involve further studies on the methodology to convert proofs, analyses of more data to investigate possible heterosis, or genotype × environment interactions for more traits and breeds. So far, most investigations are limited to milk production traits in various Friesian populations. © 1987, American Dairy Science Association. All rights reserved.