Preweaning growth rate and weaning traits of Angus, zebu and zebu-cross cattle.

A 4-yr study was conducted on the preweaning growth rate and weaning traits of 620 calves from: (1) Angus (A), Brahman (B), Brangus (BR) and Africander-Angus (AF) dams sired by A and B bulls; (2) BR dams mated to BR sires and (3) AF dams mated to AF sires. Heifers were placed in the breeding pastures as 2-yr-olds and exposed to bulls for 75 d. Breed groups differed (P less than .01) in weaning age (WA), average daily gain to weaning (ADG), 205-d weight (WW), conformation score and condition score. The reciprocal (A x B and B x A) crossbred calves exceeded (P less than .01) the straightbred A and B calves by 161 g (25.2%) in ADG, 36.6 kg (23.1%) in WW and 1.3 (16.7%) in condition score, but were not different in WA or conformation score. The WW of the A x B and B x A crossbred calves were similar, 194.6 and 194.2 kg, respectively. Calves sired by A bulls were born earlier (P less than .01) in the year and had higher conformation and condition scores than calves sired by B bulls. Calves sired by B bulls from BR and AF dams exceeded (P less than .01) the ADG and WW of calves sired by A bulls by 50 g and 15.6 kg, respectively. Calves from A dams were older (P less than .01) at weaning and had higher conformation scores but gained less rapidly than calves from B dams. The BR calves exceeded (P less than .01) the AF calves in WW by 14.5 kg, and the crossbred calves from BR dams exceeded (P less than .01) the crossbred calves from AF dams by 12.3 kg. Mating BR or AF dams to A sires to obtain crossbred calves did not improve calf rate of gain or weaning weight.