Effects of the degree of steam flaking of corn and concentration of dietary wet distillers grains on energy metabolism of feedlot cattle*

The objective of this study was to determine the effects of degree of steam flaking of corn (SFC) on energy metabolism of finishing cattle fed diets containing wet distillers grains with solubles (WDGS). Crossbred steers (n = 4; initial BW = 308 ± 7.0 kg) were randomly assigned to 4 diets containing 0% or 20% WDGS and corn steam flaked to either 321 or 270 g/L bulk density (26 or 22 lb/bu, respectively) in a 2 × 2 factorial arrangement. Energy metabolism was measured in respiration chambers with a 4 × 4 Latin square design. There were no interactions between WDGS concentration and SFC bulk density for nutrient digestion, nitrogen metabolism, or energy metabolism values. Digestibility of OM, NDF, and ether extract were not influenced by the degree of steam flaking of corn. Decreasing bulk density of SFC increased starch digestion, tended to increase the ratio of DE to digestible OM, and numerically decreased the plasma urea-N concentration, but did not significantly affect ME concentration or the DE:TDN ratio. Replacing SFC with 20% WDGS decreased fat digestion but did not affect digestion of other nutrients or dietary energy values. Results suggest that increasing the degree of steam flaking of corn to less than 321 g/L does not improve diet digestibility or energy metabolism of cattle fed diets containing 0% or 20% WDGS.