Submitted to: Livestock Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/21/2012
Publication Date: 7/19/2012
Citation: Waterman, R.C., Geary, T.W., Paterson, J.A., Lipsey, R.J., Shafer, W., Berger, L.L., Faulkner, D.B., Homm, J.W. 2012. Early weaning in Northern Great Plains beef cattle production systems: III. Steer weaning, finishing and carcass characteristics. Livestock Science. 148(3):282-290. Interpretive Summary: For extensive arid and semi-arid livestock production systems, timing and amount of precipitation are crucial for growth of grasses found on rangelands. Furthermore, as season’s progress, temperatures increase, and precipitation events decline, decreases in forage quality and quantity can have a very negative influence on livestock production. Steers weaned at nontraditional ages < 150 d of age often have improved ADG and are subsequently heavier at more traditional weaning times around 205 d of age. In addition, a greater percentage of early weaned steers have the opportunity to be graded in the upper 2/3 of choice or higher than normal or traditionally weaned steers finished on similar diets. Conclusion from this research strongly support that early weaned steers reach maturity sooner during the finishing phase. However, if early weaned steers are not identified prior to entrance into the feed yard and are instead harvested with normal weaned steers of similar genetics and age they may produce less desirable carcasses that result in discounts. In the present study, steers that received an ultrasound measurement every 28-d greatly improved their opportunity to be harvested at an optimal point to produce a favorable yield grade and quality grade.
Technical Abstract: Studies were conducted to evaluate the effect of weaning of steer calves on BW gain, feedlot performance, and carcass characteristics in two herds located in the Northern Great Plains, USA. Steer calves from predominantly Angus × Hereford dams were stratified within dam age and calving date (Fort Keogh Livestock and Range Research Laboratory (LARRL), Miles City, MT, USA; n = 354) and randomly assigned to one of three weaning treatments. Steer calves from Angus and Angus × Simmental dams (n = 200; Judith Gap (JG), MT, USA) were stratified within breed group by age, calving date, and AI sire. Steer calves either remained with their dams until normal weaning (NW) at approximately 213-d of age or were early weaned at approximately 80-d of age onto one of two early weaning (EW) diets. Steer calves assigned to EW treatments received one of the following diets: 1) 17.5% CP (69% RDP and 0.82 Mcal/kg NEm; or 2) 17.5% CP (57% RDP) and 0.84 Mcal/kg NEm. At time of normal weaning all LARRL steers were gathered and brought into lots at LARRL and held for 30-d before being sold to a commercial feedlot. Sire-identified steers from JG were sent to the University of Illinois for a finishing trial while remaining non-sire identified steers were sent to a commercial feedlot following a 28-d holding period. Steers that were EW were heavier (P < 0.0001) at time of normal weaning and entered the finishing phase in greater BW (P < 0.0001) than NW steers from both LARRL and JG studies. Age at harvest was similar for LARRL weaned steers (P = 0.79) whereas sire identified JG steers that received the EW treatment were harvested at a younger age (P = 0.0005) than NW steers. Results from the present studies strongly support the concept that early-weaned steers reach maturity sooner during the finishing phase. However, if early-weaned steers are not identified prior to entrance into the feed yard and harvested with normal weaned calves of similar genetics and age, then early-weaned steers may be subject to discounts and receive undesirable yield grades of 4 or greater.