Simultaneous genetic evaluation of simulated mastitis susceptibility and recovery ability using a bivariate threshold sire model |
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| Authors: | B G Welderufael D J de Koning L L G Janss J Franzén W F Fikse |
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| Institution: | 1. Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden;2. Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark;3. Center for Quantitative Genetics and Genomics, Department of Molecular Biology and Genetics, Aarhus University, Tjele, Denmark;4. Department of Statistics, Stockholm University, Stockholm, Sweden |
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| Abstract: | The aim of this study was to develop a new approach for joint genetic evaluation of mastitis and recovery. Two mastitis incidences (0.28 and 0.95) measured via somatic cell count and three between traits genetic correlations (0.0, 0.2, and ?0.2) were simulated for daughter group sizes of 60 and 240. A transition model was applied to model transitions between healthy and disease state. The RJMC package in DMU was used to estimate (co)variances. Heritabilities were consistent with the simulated value (0.039) for susceptibility and a bit upward biased for recovery. Estimates of genetic correlations were ?0.055, 0.205, and ?0.192 for the simulated values of 0.0, 0.2, and ?0.2, respectively. For daughter group size of 60, accuracies of sire EBV ranged from 0.56 to 0.69 for mastitis and from 0.26 to 0.48 for recovery. The study demonstrated that both traits can be modeled jointly and simulated correlations could be correctly reproduced. |
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| Keywords: | Dairy cow health state transition probability udder health recovery |
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