R. L. Powell, A.H. Sanders, and H.D. Norman
Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350
2006 J. Dairy Sci. (?)
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International Bull Evaluation Service Holstein evaluations from May 2005 were examined for country bias by comparing full-brother families. Countries with more than 25 bulls in multicountry full-brother families were included. The model fit evaluation on the US scale by absorbing full-brother family and producing solutions for country of most daughters relative to US bulls. Over 20,000 bulls were included in the analysis. The experiment was repeated fitting evaluations on the scales of 9 countries other than the United States. On all country's scales, bulls from Australia, Germany, Great Britain, and Japan had an advantage in estimated breeding value (EBV) for milk over full brothers from the United States and Italy. Bulls from Australia, Great Britain, and South Africa had an advantage in EBV fat. For EBV protein, bulls from Germany, Great Britain, Japan, and South Africa had an advantage, whereas bulls from The Netherlands were disadvantaged. For SCS, US bulls were advantaged only compared with bulls from South Africa. Significance of biases was similar across country scales of the Interbull evaluations. Cause of biases is unknown; perhaps bias in evaluations of local versus foreign bulls is present in the national evaluations submitted to Interbull and is propagated throughout national scales in the Interbull results.
(Key words: genetic evaluation, International Bull Evaluation Service, genetic correlation)