Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2007
Publication Date: 2/1/2008
Citation: Brown, M.A., Lalman, D.L. 2008. Preweaning performance of calves from Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano sires bred to Brangus cows managed on native rangeland or improved forages. Professional Animal Scientist. 24:67-75. Interpretive Summary: Given that preweaning performance in beef calves is a function of animal genetics, management or environment, and the interaction of genotype with management or environment, there is a need to evaluate newer breeds in different production environments. Research at the Grazingland Research Laboratory from 2002 to 2005 evaluated calves from Brangus dams sired by Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano sires on two preweaning forage systems: improved warm season forages and native rangeland. Results from the research provided some evidence that differences in preweaning performance depended on preweaning forage systemsthe forage that the cows and calves were managed on, sire breed of calves, age of dam, and sex of calf. More specifically, preweaning forage system had an impact on birth weight in Romosinuano-sired calves. In expression of 205-d weight, Bonsmara- and Brangus-sired calves seemed to benefitted from native rangeland as a preweaning environment compared to management on improved forages. In weaning condition score, calves from two of the later maturing sire breeds (Charolais and Gelbvieh) seemed to benefitted from a preweaning management on improved forages while the other sire breeds seemed to benefitted from preweaning management on native rangeland. Thus, it is evident that sire breed differences in preweaning performance can depend on the specific production management system and matching animal genetics with production environment is an important consideration in development of efficient beef production systems.
Technical Abstract: Preweaning data on 511 calves from 187 Brangus cows and 129 Bonsmara, Brangus, Charolais, Gelbvieh, Hereford, and Romosinuano sires were measured over a four year period with the objectives to of determineing sire breed, sex, and age of dam differences under two preweaning forage environments common to the Southern Great Plains (native tallgrass rangeland vs. improved warm-season forages). Calves were weighed within 24 h of birth, bull calves were banded, and calves were not creep-fed during the preweaning period. Weaning was doneCalves were weaned in the fall at an average age of 209 d when and weights and condition scores were taken. Sire breed differences in birth weight were not consistent across forage (P < 0.05) with Romosinuano-sired calves on improved forages intermediate in birth weight compared to other sire breeds but ranked lightest on native rangeland. Calves from 4-yr-old and mature cows (5 yr +) on native rangeland were heavier at birth than calves from 2-, and 3-, and 4-yr-old dams (P < 0.05) and there was a trend for calves from 4-yr-old dams to be heavier than calves from 2-, and 3-yr-old dams (P < 0.05, P < 0.13, respectively)on native rangeland. butHowever, there was little evidence of age of dam differences in calf birth weight on improved forages. Sex differences tended to bewere numerically larger in Charolais- and Romosinuano-sired calves than other sire breeds. Calves from Charolais and Gelbvieh tended to bewere heavier in 205-d weight than calves from other sire breeds on improved preweaning forages (P < 0.05, except Gelbvieh vs. Hereford, P < 0.12) while on native preweaning forages, Bonsmara-, Charolais-, and Gelbvieh-sired calves were similar but heavier than Brangus- and Romosinuano-sired calves (P < 0.10). Steer calves were substantially heavier than heifer calves on improved preweaning forages (P < 0.01) but sex differences on native preweaning forages were smaller and not significant. Sire breed differences were not significant on improved preweaning forage for weaning condition score., but there was a trend for weaning condition score of Romosinuano- and Brangus-sired calves to be lower than other sire breeds. On native preweaning forage, weaning condition scores were higher for calves sired by Bonsmara and Hereford (P < 0.05) compared to Brangus-, Charolais-, and Gelbvieh-sired calves and Charolais-sired calves were lower than other sire breeds (P < 0.05). These results provide evidence of non-additive relationships between preweaning forage systems, sire breed of calves, age of dam, and sex of calf in preweaning traits. Consequently, Consideration should be given to appropriate combinations of these effects in development of efficient preweaning systems will require appropriate combinations of these effects.