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KMID : 1025520000420020135
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Journal of Animal Science and Technology
2000 Volume.42 No. 2 p.135 ~ p.140
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A Study on Optimum , Minmum Size of Contemporary Group in Dairy Cattle Genetic Evaluation
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Abstract
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Three, 6 and 9 of contemporary group sizes by five types including conventional genetic evaluation were examined with simulated data to study accuracy of estimation. Four alternatives were suggested. Method l and 2 assumed that genetic values of cows missing sire identity were population and contemporary group average. Method 3 and 4 accounted for genetic values through producing abilities estimated as random and fixed effects, respectively. Contemporary group effects were estimated more accurately as contemporary group size increased(3, 6 and 9), but breeding values were less increased in accuracy. Accuracies of alternative methods slightly exceeded those of conventional method for all estimated effects and all minimum group sizes. Method 3 had high increases in accuracy compared with the other alternatives. In the estimation of contemporary group effects, there were significant differences of increases in accuracy among the group sizes 3, 6 and 9. No significant differences in increases of accuracy in the estimation of cow and sire breeding values were shown among the group sizes.
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