RELATIONSHIP OF BEEF SIRE EXPECTED PROGENY DIFFERENCE TO MATERNAL PERFORMANCE OF CROSSBRED DAUGHTERS

Cumulative milk production of crossbred daughters of sires of several breeds was estimated using weigh-suckle-weigh procedures. Pooled-acros s-breed analyses were conducted to determine, in retrospect, relations hips of sire EPD values for milk and total maternal value to daughter milk yield and daughter's offspring weaning weight. The pooled coeffic ient for regression of daughter 214-d milk yield on sire milk EPD was 13.4 kg/kg (residual correlation was .14). The overall mean estimated milk yield was 1,262 kg, suggesting that a difference in sire milk EPD of 1 kg corresponded to a difference of approximately 1% in cumulativ e daughter milk yield. The pooled coefficient for regression of daught er's offspring 214-d weight on sire total maternal EPD was 1.18 kg/kg (residual correlation was .17). All regression and correlation coeffic ients stated above were significantly greater than zero. Breeders who use sire milk and total maternal EPD values as selection tools should expect such selection to be effective, on average, but should also exp ect that a substantial proportion of individuals or small groups may n ot rank as predicted.