ARS | Publication request: Postweaning feed restriction effects on steer feedlot performance and carcass characteristics

Submitted to: Western Section of Animal Science Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: June 1, 2012
Publication Date: July 16, 2012
Citation: Endecott, R.L., Shipp, B.L., Macneil, M.D., Alexander, L.J., Roberts, A.J. 2012. Postweaning feed restriction effects on steer feedlot performance and carcass characteristics. Western Section of Animal Science Proceedings. 90(Suppl. 3):298. Abstract No. T128.

Technical Abstract: The objective was to evaluate impacts of 2 levels of supplemental feed provided to cows during late gestation and 2 levels of feed provided to their sons during postweaning development on subsequent feedlot performance and carcass characteristics. Bull calves (n = 56 in 2010; n = 51 in 2011) were born from dams receiving adequate (1.8 kg/d) or marginal (1.2 kg/d) winter supplementation. After weaning, bulls were developed on ad-libitum (Control) or 27% less feed (Restricted) for ~140 d. Bulls were then band-castrated and placed on an 80% corn finishing diet ad libitum. Individual intakes were measured with a GrowSafe system for the final 100-150 d of the finishing period. Cattle were harvested at a commercial packing plant and carcass data were collected. Dam winter supplementation effects were not detected (P = 0.22). Postweaning phase ADG exhibited a postweaning treatment × year interaction (P < 0.01). Restricted calves had similar ADG in both years (0.64 vs 0.68 ± 0.03 kg/d) and gained less than Control calves. Control calves had greater ADG in 2010 than in 2011 (1.16 vs 1.03 ± 0.03 kg/d). Postweaning treatment did not impact feed intake during the finishing phase (P = 0.29; 13.0 vs 12.8 ± 0.22 kg/d for Restricted vs Control; as-fed basis). During the finishing phase, ADG exhibited a postweaning treatment × year interaction (P < 0.01). Restricted steers had similar ADG in both years (1.25 vs 1.27 ± 0.05 kg/d) and gained more than Control steers. Control steer ADG was less in 2010 than in 2011 (0.92 vs 1.13 ± 0.05 kg/d). Compared to Control steers, Restricted steers had lower (P = 0.08) final BW (603 vs 623 ± 9 kg), HCW (357 vs 373 ± 6 kg), and yield grade (2.71 vs 2.89 ± 0.10). However, back fat thickness (1.09 vs 1.14 ± 0.05 cm), ribeye area (85.4 vs 85.8 ± 0.98 cm2), and marbling score (5.59 vs 5.50 ± 0.12) were not different (P = 0.34). Calves restricted during postweaning development gained more efficiently, and when harvested on a common date, had lower carcass weights and yield grade, but similar fat thickness, ribeye area and quality grade compared to their ad libitum-fed counterparts.