Influence of Inbreeding Depression on Genetic (Co)Variance and Sire-by-Year Interaction Variance Estimates for Weaning Weight Direct-Maternal Genetic Evaluation

  • Lee, C. (Institute of Environment and Life Science, Hallym Univ.) ;
  • Pollak, E.J. (Department of Animal Science, Cornell University)
  • Received : 1996.10.23
  • Accepted : 1997.02.12
  • Published : 1997.10.01


This study examined the effects of ignoring inbreeding depression on (co)variance components for weaning weight through the use of Monte Carlo simulation. Weaning weight is of particular interest as a trait for which additive direct and maternal genetic components exist and there then is the potential for a direct-maternal genetic covariance. Ignoring inbreeding depression in the analytical model (.8 kg reduction of phenotypic value per 1% inbreeding) led to biased estimates of all genetic (co) variance components, all estimates being larger than the true values of the parameters. In particular, a negative bias in the direct-maternal genetic covariance was observed in analyses that ignored inbreeding depression. A small spurious sire-by-year interaction variance was also observed.