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https://hdl.handle.net/2142/83645
Description
Title
Weaning Management Systems for Beef Production
Author(s)
Myers, Steven Eric
Issue Date
1998
Doctoral Committee Chair(s)
Faulkner, Dan B.
Department of Study
Animal Sciences
Discipline
Animal Sciences
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
Ph.D.
Degree Level
Dissertation
Keyword(s)
Biology, Animal Physiology
Language
eng
Abstract
Three studies were conducted to determine the effects of weaning management system on steer growth and carcass traits. In year one of Study 1, cow-calf pairs were randomly assigned to one of three treatments, where the steer calves were: (1) weaned at 168 d of age and placed on a finishing diet (EW), (2) supplemented with grain from 168 to 222 d of age on pasture while nursing their dams and then placed on a finishing diet (NWC), and (3) on pasture from 168 to 222 d of age while nursing their dams and then placed on a finishing diet (NW). In year two of Study 1, potential breed differences were also evaluated using steers of three different breed types: (1) Angus $\times$ Hereford (BRI), (2) Angus $\times$ Simmental (CON), and (3) Angus $\times$ Wagyu (WAG). In year one, EW steers gained 100% faster (P =.0001) prior to 231 d, had lower intakes (P =.008), better feed conversions (P =.002), and higher marbling score (P =.003) compared to the average of NWC and NW steers. In year two, EW steers had higher gains (P =.0006) overall, lower intakes (P =.0008) and better feed conversions (P =.0001) compared to the average of NWC and NW steers. The percentage of BRI steers grading choice or greater was 21% higher, and percentage of steers grading average choice or greater was 33% higher compared to CON. Cows with EW steers had higher gain than cows with NW steers (P =.0001) prior to 222 d. In Study 2, steers were early weaned at 117 d and were: (1) fed ad libitum high concentrate after weaning (CONC), or (2) grown on pasture for 82 d, followed by high concentrate finishing (PAST). Potential breed differences were evaluated using steers of three different breed types: (1) 1/4 Angus $\times$ 3/4 Simmental (BRI), (2) 3/4 Simmental $\times$ 1/4 Angus (CON), and (3) 1/2 Wagyu $\times$ 1/4 Angus $\times$ 1/4 Simmental (WAG) crossbred. CONC steers had higher gain (P =.0001), lower intake (P =.0001), better gain:feed (P =.008), consumed the same amount of total concentrate (P =.97), and had reduced liver (P =.15) and rumen (P =.01) weights as a percentage of hot carcass weight when compared to PAST steers. BRI steers reduced finishing days (P =.008) and total concentrate consumed (P =.0003) compared to CON steers. WAG steers had more days finishing (P =.05), lower gain (P =.0003), lower intake (P =.07), more undesirable efficiencies (P =.10), consumed the same amount total concentrate (P =.60), and improved quality grades (P =.006) compared to BRI steers. In Study 3, 168 crossbred steers were used to compare the effects of three weaning ages on cow-calf performance and steer carcass traits. Steers were weaned at either 90, 152 or 215 d of age and placed on a finishing diet. Early weaned steers had improved gain (linear, P =.005), improved gain:feed (linear, P =.004), but required more total concentrate (linear, P =.03) when compared to steers weaned at 215 days. Cow gain (linear, P =.0001) and body condition score (linear, P =.0001) improved by early weaning.
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