Effects of reduced-fat modified wet distillers grains with solubles on beef steer performance and carcass composition

Abstract

Two experiments were conducted to examine feedlot performance and carcass characteristics of beef steers fed reduced-fat, modified wet distillers grains with solubles (RMDGS). Angus cross steers were stratified by BW in each experiment and assigned to 20 pens containing either 6 or 7 steers per pen. In Exp. 1, pens were randomly assigned to 1 of 4 diets containing 15% corn silage and 1) 25.0% RMDGS and 57.04% whole shelled corn (25 RMDGS); 2) 40.0% RMDGS and 42.69% whole shelled corn (40 RMDGS); 3) 70.0% RMDGS and 12.49% whole shelled corn, fed 84 d, then switched to 40 RMDGS (70/40 RMDGS); 4) 70.0% RMDGS and 12.49% whole shelled corn (70 RMDGS). In Exp. 2, the same diets were fed except 70/40 RMDGS was replaced with a diet containing 73.16% whole shelled corn and 9.60% soybean meal (0 RMDGS). In Exp. 1, no significant differences in DMI, ADG, G:F, or carcass characteristics were found. In Exp. 2, DMI increased (P = 0.003) with increasing RMDGS. In Exp. 2, LM samples from 2 steers in each pen at each slaughter date were analyzed. There were no differences (P > 0.05) in percentage of moisture, fat, or cooking loss in shear force of rib steaks among treatments. Steers fed the 70 RMDGS diet produced rib steaks with lower a* (P < 0.05) following 7 d of chilled storage. Fatty acid analysis showed an increase (P < 0.05) in SFA at the expense of MUFA because of RMDGS supplementation. Increases were observed in PUFA, PUFA/SFA, conjugated linoleic acid, and omega-6 fats, with increasing RMDGS. Steers fed 70 RMDGS had inconsistent feedlot performance with a trend for lighter HCW, lower QG, and reduced meat quality.