Sire × sex interactions and sex differences were investigated for preweaning growth rate and weaning weight using data from 487 Angus calves representing the bull, steer and heifer progeny of 24 sires over a 3-year period. There were 394 calves involved in analyses of feedlot performance and 14 carcass traits. Approximately one-half of the male calves from each sire group were randomly selected for castration at an average age of 3 months. Calves were weaned at an average age of 205 days and slaughtered following a 168-day postweaning feedlot period. No significant sire × sex interactions were obtained for any growth or carcass traits. Bulls had a nonsignificant advantage of 3.0 kg over steers in 205-day adjusted weaning weight while steers were 12.1 kg heavier than heifers. Large sex differences were obtained for feedlot average daily gain as indicated by means of 1.33, 1.16 kg and 0.94 kg for bulls, steers and heifers, respectively. Carcass weight per day of age was 0.70 kg for bulls, 0.65 kg for steers and 0.57 kg for heifers. Bulls were from 2.3 to 2.7% higher than steers in carcass cutability each year; differences between steers and heifers were nonsignificant and varied in direction. Sire effects were significant for 15 of the 18 traits analyzed. Year × sex interactions were significant for preweaning average daily gain, weaning weight, yearling weight, percent kidney fat, carcass conformation, marbling score, carcass grade and carcass cutability. Absence of significant sire × sex interactions suggests that differences between the sexes tend to be similar for different sires and that observed discrepancies can be attributed to random variation. These results indicate that progeny tests could be conducted in which sires are evaluated on the basis of progeny of different sexes providing adequate sex adjustments are available.
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Tanner et al. (1970) studied this question.