Pre- and postweaning calf performances in crossbred cattle from Hereford, Braford, and Bonsmara sires and Angus and Brangus dams1

Growth traits were evaluated on 560 calves (288 male and 272 female calves) to determine the source and extent of tropical adaptation affecting calf pre-weaning and postweaning growth performances. Calves with Brangus dams were sired by Braford (BFBN; n = 115; 38% Brahman), Hereford (HEBN; n = 92; 19% Brahman), and Bonsmara (BOBN; n = 139; 19% Brahman and 31% Africander) sires. Calves with Angus (AN) dams were sired by Hereford (HEAN; n = 95) and Bonsmara (BOAN, n = 119; 31% Africander) sires. Growth performances of BFBN and HEBN calves were similar (P > 0.15) for an array of growth traits. However, BFBN and HEBN either tended to (P < 0.10) or had (P < 0.05) greater adjusted birth BW, postweaning ADG, and adjusted 452-d BW when compared with BOBN. Calves with AN dams and Bonsmara sires had greater preweaning ADG (P < 0.05), adjusted 205-d BW (P < 0.01), and adjusted 452-d BW (P < 0.01) than HEAN calves. Among calves with Brangus dams, extent (BFBN vs. HEBN) of tropical adaptation was not important in terms of growth, but source (BFBN vs. BOBN and HEBN vs. BOBN) of tropical adaptation did not favor those calves with Africander breeding. However, for calves with AN dams, the use of Bonsmara sires (BOAN) imparted a growth advantage relative to the HE sires (HEAN). It is important that tropical adaptation, in terms of Brahman and Africander breeding, be imparted to the calf directly but more importantly, that Brahman breeding is imparted maternally.