Submitted to: Professional Animal Scientist
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2008
Publication Date: 2/2/2008
Citation: Brown, M.A., Wang, X., Gao, F., Wu, J., Lalman, D.L. 2008. Postweaning gains in calves sired by six sire breeds evaluated on two preweaning forages and two postweaning management systems. Professional Animal Scientist. 24:224-231. Interpretive Summary: Interpretive Summary: Development of efficient beef production systems will require appropriate matching of animal genetics to production environment. Results from research at the USDA-ARS Grazinglands Research Laboratory has indicated that expression of sire breed of calf differences in postweaning gains is influenced by both preweaning and postweaning environment. For example, calves sired by non-Zebu tropically adapted breeds were not competitive as wheat pasture stockers, but Bonsmara- and Romosinuano-sired steers were competitive with Brangus-, Gelbvieh-, and Hereford-sired steers on mixed rations in drylot. Consequently, the indicated postweaning management for the two non-Zebu tropically-adapted breeds seems to be drylot on mixed rations rather than wheat pasture. Thus efficient system development, either through field systems work or through functional genomics will need to be environment specific and projected systems will need to be evaluated over a broad range of applicable environments to allow generalization within specific environments.
Technical Abstract: Technical Abstract: Postweaning ADG from 462 calves from Brangus cows and sired by 6 breeds (Bonsmara, Brangus, Charolais, Gelbvieh, Romosinuano) was measured over a 4-yr period to evaluate the impact of preweaning forage, postweaning management, sire breed, and gender on postweaning gain. Preweaning forages were improved forages (common bermudagrass or Old World Bluestem) or native rangeland. Calves from each preweaning forage were weaned at an average 209 d and stratified by sex and sire breed to one of two postweaning management systems (drylot on mixed grain rations or wheat pasture). Gains in each postweaning system were estimated from initiation of fall grazing (early to mid-November) on wheat pasture through late spring for an average of 166 d. Sire breed of calf differences were not consistent across sex of calf, preweaning management and postweaning management (P < 0.10). In general, Bonsmara- and Romosinuano-sired heifers did not perform as well as heifers from other sire breeds in either drylot or wheat pasture postweaning management. Gelbvieh-sired heifers in drylot out gained Brangus- and Charolais-sired heifers (P < 0.10) but not Hereford-sired heifers. On wheat pasture, few differences were evident among Brangus-, Charolais-, Gelbvieh-, and Hereford-sired heifers. Romosinuano-sired steers, in general, were slower gainers than steers from other sire breed groups on wheat pasture but both Bonsmara- and Romosinuano-sired steers were competitive with calves from other sire breed groups in drylot, with the exception of Charolais-sired steers that out gained than other breed groups (P < 0.10). Consequently, the indicated postweaning management for the two non-Zebu tropically-adapted breeds is drylot on mixed rations rather than wheat pasture. Results from these data indicate that genetic differences in postweaning ADG can depend on both preweaning and postweaning environments and genetic differences can be less evident in a more stressful environment such as wheat pasture. Key words: Beef cattle, sire breeds, Postweaning ADG