Submitted to: American Society of Animal Science Southern Section Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 12/21/2006
Publication Date: 2/2/2007
Citation: Brown, M.A., Lalman, D.L. 2007. Preweaning performance of calves from tropically-adapted and temperate sires and Brangus cows managed on two forage systems [abstract]. American Society of Animal Science Southern Section Meeting, February 3-6, 2007, Mobile, AL. p. 3-4. Available on-line: http://www.asas.org/southern/meetings_past.asp.
Interpretive Summary: Abstract Only
Technical Abstract: Four years of preweaning data on 511 calves from 187 Brangus cows and 129 Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano sires were used to determine sire breed, sex, and age of dam differences under two preweaning forage systems (native tallgrass rangeland vs improved warm-season forages). Calves were weighed within 24 h of birth, bull calves banded, and calves were not creep-fed. Calves were weaned in the fall at an average of 209 d. Sire breed differences in birth weight differed across forage (P < 0.05) with Romosinuano calves on improved forages heavier than counterparts on native rangeland (P < 0.01). Calves from mature cows were heavier on native rangeland than counterparts on improved forages (P < 0.01) while calves from younger cows tended to be similar on both forage systems or heavier on improved forages. Calves from Bonsmara and Brangus sire calves were heavier in 205-d weaning weight on native rangeland than improved forages (P < 0.05 and P < 0.10) whereas there was little evidence of forage differences in calves from other sire breeds. Forage differences in favor of native rangeland were evident in 205-d weights of calves from four- and five-yr old cows (P < 0.05 and P < 0.10) but not in calves from two- and three-yr old cows. Heifer calves were heavier at 205-d on native rangeland than heifers on improved forage (P < 0.05) while steer calves were similar on both forage systems. There was a trend for weaning condition score from Bonsmara sired calves to be higher (P < 0.13) on native rangeland than improved forages whereas Charolais sired calves had higher weaning condition scores on improved forages than native rangeland (P < 0.01). These results provide evidence of non-additive relationships between preweaning management systems, sire breed of calves, age of dam, and sex of calf in preweaning traits. Consideration should be given to appropriate combinations of these effects in development of preweaning systems. Key words: Beef cattle, Preweaning, Tropically adapted, Brangus