932
Does direct genetic selection for production traits degrade maternal ability in Landrace pigs?
ABSTRACT: The study estimated direct and maternal effects on production traits and evaluated the direct and maternal genetic progress over 18 years. Data analyzed were on 12,463 pigs from 15 herds, performance-tested between 1990 and 2008. Backfat thickness, test period and lifetime gains and slaughter age were analysed using an animal-maternal model in ASREML. Six models were constructed and the best model contained direct and maternal genetic effects accounting for the direct-maternal genetic covariance. Some genetic effects might have been hidden when the direct-maternal genetic covariance was not considered and uncovered by the covariance. Maternal ability remained constant despite direct selection over the years; hence there may be optimum direct genetic progress where maternal ability can be maintained. There may be room for simultaneous direct and maternal genetic improvement if both direct and maternal effects are selected for.
Keywords:
Variance components
Genetic change
Growth performance
