Effects of supplemental organic chromium on growth, feed efficiency and carcass characteristics of feedlot steers

Abstract

Effects of supplemental organic chromium (Cr) during the growing and finishing periods on feedlot steer performance and carcass characteristics were measured. One hundred and five English and Continental crossbred steers (283±22.6 kg) were allotted randomly to three dietary treatments: (1) control (basal diet: 1.33 ppm (DM) Cr; (2) basal diet with 0.2 ppm (DM) Cr supplementation; (3) basal diet with 0.4 ppm Cr (DM) supplementation. Chromium was supplied as high Cr yeast in a premix added to the diet at either 0.25 or 0.50% (as fed). Daily gain was lower ( P<0.05) in steers fed the 0.4 ppm Cr supplemented diet than by steers fed the unsupplemented or 0.2 ppm Cr diet (0.96 versus 1.11 and 1.16 kg per day). Gain-to-feed ratio (GF) over the entire period was higher ( P<0.05) for steers fed the control and 0.2 ppm Cr diets than for those fed the 0.4 ppm Cr diet (135 and 129 versus 118 g gain per kg feed). Serum cortisol was largely unaffected by Cr feeding throughout the trial. Steers fed the 0.2 ppm Cr diet had the heaviest ( P<0.05) hot carcass weights, steers fed 0.4 ppm Cr had the lightest and control steer carcass weights were statistically intermediate (315, 276, and 302 kg, respectively). Longissimus muscle area tended ( P=0.08) to be greatest with the 0.2 and 0.4 ppm Cr diet and lowest with the control diet (81.6, 77.9 and 81.3 cm 2, respectively). Marbling score (i.e. intramuscular fat deposition) was lower ( P<0.05) in steers fed the 0.4 ppm Cr diet compared with the control and 0.2 ppm Cr diets (395 versus 472 and 446, respectively). Dressing percent was higher ( P<0.05) with the control and 0.2 ppm Cr diet compared with the 0.4 ppm Cr diet (63.37 and 63.65 versus 62.16). Final USDA yield grade was highest ( P<0.05) with the control and 0.2 ppm Cr diets (2.53 and 2.32 versus 1.56). Feeding supplemental organic Cr at 0.2 ppm improved, or tended to improve, some economically important carcass characteristics. Overall, results support a supplementation level of 0.2 ppm of organic Cr to basal rations of about 1.33 ppm Cr (DM basis) due primarily to improvements in carcass quality.