| Abstrakt: |
Data from the American Angus Association, American Gelbvieh Association, and the North American Limousin Foundation were analyzed to determine whether parental genetic differences are associated with Mendelian sampling of their bull progeny or with Mendelian sampling variances and weight variances of their bull progeny's offspring. Parental differences were measured as the difference between the parents' EPD for birth weight (DIFBW), weaning weight direct (DIFWW), and yearling weight (DIFYW). A bull's data were used if both parents had calculated EPD and the bull had at least 25 progeny with records for the specific trait. Traits calculated for each bull were his Mendelian sampling (MSBull), progeny Mendelian sampling variance (MSσ2progeny), progeny weight variance (WTσ2), and progeny corrected weight variance (CWTσ2= adjusted weight minus appropriate dam EPD) for birth, weaning, and yearling weights. Pearson correlations were computed between DIFBW, DIFWW, and DIFYWand MSBull, MSσ2progeny, WTσ2, and CWTσ2for each trait, within each breed. Across breeds, the correlations ranged from −.07 to .11 for MSBull.01 to .14 for MSσ2progeny, −.06 to .09 for WTσ2, and −.06 to .08 for CWTσ2. Although some of the correlations were significantly different from zero their relatively small magnitude indicates little relationship between parental differences in genetic merit and subsequent offspring variability for each of the three breeds. |
