Preweaning Performance, Heterosis, and Direct and Maternal Breed Effects in Angus, Hereford, Red Poll, Santa Gertrudis, and Reciprocal-Cross Calves

Production records of 1,631 cow-calf pairs were used to evaluate breed and breed combination differences in calf performance to weaning and to estimate heterosis, maternal breed effects, and direct breed effects. Included were straight-bred Angus (A), Hereford (H), Red Poll (RP), and Santa Gertrudis (SG) and reciprocal crosses. Data were birth weight (BWT), ADG, weaning weight (WWT), weaning grade, and weaning body condition score (WBCS). Data were analyzed using mixed model procedures in which sire within sire breed was a random effect used for testing direct breed effects. The interaction of sex of calf by breed of dam was evident (P < 0.01) for ADG and WWT. The interaction of sire breed with dam breed was important for BWT, ADG, WWT, and WBCS (P < 0.05). Heterosis effects were evident (P < 0.01) for BWT, ADG, and WWT for A × H crosses. The A × SG crosses demonstrated heterosis for ADG, WWT, and WBCS (P < 0.01). The A × SG calves were 1.65kg heavier at birth, were 24.7kg heavier at weaning, and graded one-half point higher than their purebred contemporaries (P < 0.05). Maternal breed effects were evident for BWT and ADG for all reciprocal crosses except for ADG for H × RP and A × SG. The A × SG, A × H, A × RP, and A × SG had negative direct breed effects for BWT (P < 0.01). This study indicates that heterosis, maternal breed effects, and direct breed effects do influence preweaning performance in a challenging environment, and specific breed contributions should be considered when developing an effective crossbreeding program.