Application of selection index method to combine two generations of estimated breeding value in pigs.
1989
Takahashi H. | Sugimoto T. | Nibe A. | Schinckel A. | Amemiya Y.
Three different applications of the selection index method are compared on the basis of the accuracy (rIT) and the prediction error variance (PEV) to estimate breeding value (EBV) on age in day to 105kg (DAYS) and the back fat thickness at 105kg of body weight (BF). Individual pigs came off-test, full-sibs and half-sibs to the individual, dam and full-sibs and half-sibs to the dam are considered as the source of information. Three methods are 1) direct method - apply the selection index method directly to the available data, 2) two step method - calculate EBV of a pig and the dam separately by using own, full-sibs and half-sibs data and then re-apply the selection index method to combine the dam's EBV to the pig's EBV, 3) simplified two step method - approximate covariance between the dam's EBV and the pig's EBV by the simple formula and then use this approximated covariance to combine these two EBVs. Under the practical 62,500 combinations of the different number of information, the increase in PEV by the method 2 and the method 3 as compared to the method 1 was less than 0.006 with DAYS and less than 0.012 with BF. Difference of the accuracies between method 1 and either method 2 or 3 was less than 0.004 for both traits. Simplified two step method is effective to calculate EBVs with a large data set, especially with small business computer.
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