Net Energy of Regular and Waxy Sorghum Grains for Finishing Steers

Finishing studies were conducted to compare feedlot performance and carcass traits with steers fed rations containing regular and waxy sorghum grain. Net energy values for maintenance (NEm) and gain (NEg) were determined for the rations and the grains from energy retention data determined by the comparative slaughter technique. The waxy grain contains glutenous starch which is almost entirely amylopectin and the regular grain non-glutenous starch composed of about 75% amylopectin and 25% amylose. The grains were dry rolled and fed in isonitrogenous rations containing in percent: grain, 83.9; cottonseed hulls, 10.0; cottonseed meal, 4.3; urea, 0.7; trace mineral salt, 0.5; CaCO3, 0.5; and elemental sulfur, 0.1. Feedlot performance and carcass traits were comparable between the two grains when expressed both on a live weight and carcass weight basis. Feed utilization was more efficient with the waxy grain both on a live weight (P<.10) and a carcass (P<.05) basis. NEmof the rations was 1.35 and 1.41 megcal. per kg., and of the grains 1.43 and 1.50 megcal. per kg. for the regular and waxy sorghum grains, respectively. NEgvalues were 0.86 and 1.10 megcal. per kg. for the rations, and 0.95 and 1.24 megcal. per kg. for the grains listed in the above order. These results suggest that the glutenous starch in the waxy grain provided a more readily available energy source than the non-glutenous starch in the regular sorghum grain.