Author
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POWELL, REX |
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Submitted to: Journal of Dairy Science
Publication Type: Abstract Only Publication Acceptance Date: 3/25/1996 Publication Date: N/A Citation: N/A Interpretive Summary: Technical Abstract: International genetic evaluations of Holstein bulls by the International Bull Evaluation Service were examined. In February 1995, genetic correlations were assumed to be .995 for all countries, and national evaluations weren't included for bulls not used in the country as young bulls. August 1995 evaluations included genetic correlations of .87 to .96, ,and each country determined whether their national evaluations were included for bulls not used there as young bulls. International evaluations from February and August and corresponding national evaluations from The Netherlands, France, Germany, Italy, and the U.S. were compared along with international evaluations from Canada, Denmark, Finland, and Sweden. Only protein results are reported. Correlations were >.99 between national and international evaluations for February and August and among February international evaluations on various country scales; correlations among August international evaluations were as low as .96. For February, only 2.6% of bulls had data from more than 1 country; that percentage increased to 4.7 for August because of inclusion of more foreign bulls. The source for top bulls was substantially affected by varying genetic correlations; 59-62 of the top 100 bulls for protein yield on other country scales were U.S. bulls for February evaluations but only 38-50 for August. Decline in U.S. representation was partially due to the 10.5% increase in estimated sire genetic standard deviation. Implementation of varying correlations also reduced U.S. representation. More importantly it widened the range. Use of appropriate genetic correlations and additional bull evaluations increased acceptance of international evaluations and should improve their accuracy, which could increase genetic progress for all countries. |
