Sire × Environment Interactions and Genetic Correlations of Sire Progeny Performance across Regions in Dam-Adjusted Field Data

The original data were from 109,210 birth and 94,947 weaning weight records obtained from the North American Limousin Foundation. Initial analyses of the data yielded estimates of sire × contemporary group/region interaction variances that were larger than the sire variance for both birth and weaning weight. Accounting for dams reduced the magnitude of the sire × contemporary group/region variance by 20 and 38% for birth and weaning weight, respectively. However, even after the reduction, these interactions were of a magnitude to conclude the rank changes of sire progeny performance were occurring across contemporary groups. The average weighted genetic correlation estimate for birth weight of sire expected progeny differences (EPD) across regions before accounting for dams and sire × contemporary group effects, after accounting for dams and after accounting for dams and sire × contemporary group effects were .71, .78 and .81, respectively. Similar correlations for weaning weight before accounting for dams and interaction effects, after accounting for dams and after accounting for dams and interactions were .55, .66 and .69, respectively. Accounting for dams improved the genetic correlations of sire EPD averaged across regions; however, some individual regions still had correlations below .60 after accounting for dams.