Expected genetic gains from desired change index in selection for increased litter size in a closed swine herd
1999
Satoh, M. (National Inst. of Animal Industry, Kukizaki, Ibaraki (Japan)) | Furukawa, T. | Ishii, K.
Selection index based on family information was used to estimate expected genetic gains resulting from selection based on animal model BLUP of breeding values. The breeding objective was to achieve predetermined desired changes for average daily gain (DG), back fat thickness (BF) and litter size at birth (LS). Information for selection was on the candidate's parents and their full and half sibs found in generation F-1, grand parents and their full and half sibs found in generation F-2, F-1 was defined as animals in the i(th) generation back. The candidate for selection was found in the current generation F-0. Records from F-o to F-4 were used in the present study. All animals were assumed to have one record for DG and BF and each female animal except those in current generation was assumed to have one record for LS. Each male was mated to 5 females. The number of candidates for selection per litter was varied from 2 to 4. The respective heritabilities of 0.3, 0.5 and 0.1 for DG, BF and LS, with genetic and phenotypic correlations between DG and BF of 0.2 were used. No correlations between LS and DG and BF were assumed. When desired change of DG, BF and LS was 2:2:1, estimated genetic gain of each trait using selection on restricted BLUP was as large as that on two-trait selection index for DG and BF and individual phenotype for LS. When desired change of DG, BF and LS was l:1:2, estimated genetic gain of LS using restricted BLUP was equal to that using single trait BLUP for LS. Furthermore, if the population was at the optimum for BF, larger genetic gain was expected for DG and LS
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