MATERNAL PERFORMANCE OF FIRST-CALF CROSSBRED BEEF COWS IN RELATION TO SIRE EXPECTED PROGENY DIFFERENCES (EPDs)

Cumulative milk production of crossbred daughters of sires of several breeds was estimated using weigh-suckle-weigh procedures. Pooled-across-breed analyses were conducted to determine, in retrospect, relationships of sire expected progeny difference (EPD) values for milk and total maternal value to daughter milk yield and daughter's offspring weaning weight. The pooled coefficient for regression of daughter 214-day milk yield sire milk EPD was 13.4 Ibllb (residual correlation was .14). The overall mean estimated milk yield was 2,782 Ib, suggesting that a difference in sire milk EPD of 1 Ib corresponded to a difference of approximately 5% in cumulative daughter milk yield. The pooled coefficient for regression of daughter's offspring 214-day weight on sire total maternal EPD was 1.1 8 Ibllb (residual correlation was .17). 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 expect that a substantial proportion of individuals or small groups may not rank as predicted.