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Alternative models for genetic evaluation of pre- and post-weaning mortality traits were investigated. For pre-weaning mortality, the best model accounted for direct piglet effects, common litter effects of both the nurse sow and biological dam, repeated records of the nurse sow and the maternal nurse sow genetic effects. For post-weaning mortality, the most parsimonious model included only direct piglet effects and the common litter effects of both the nurse sow and biological dam. After accounting for systematic effects, genes of the piglet contribute to both pre- and post-weaning mortality (direct h² = 0.02 ± 0.002 for pre- and post- weaning), whereas the nurse maternal genes only contribute to pre-weaning (maternal m² = 0.01 ± 0.002). While heritabilities were low, there is potential for genetic improvement of both pre- and post-weaning mortality traits. |
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