Comparison of wheat or corn dried distillers grains with solubles on performance, carcass characteristics, rumen fermentation parameters and diet digestibility of feedlot cattle

Two trials were conducted, one using crossbred steers (Trial 1; N=275; 376±24 kg) and a second using Hereford heifers (Trial 2; N=5; 420±6 kg) to evaluate the performance, carcass quality, rumen fermentation and nutrient digestibility of cattle fed wheat or corn dried distillers grains with solubles (DDGS). The control ration averaged 87.7% rolled barley grain, 5.6% supplement and 6.8% barley silage (DM basis) over both trials. Dietary treatments included replacement of barley grain at 20 or 40% of the diet (DM basis) with wheat or corn DDGS. For Trial 1, steers were slaughtered at a constant finish weight of 645 kg. Data was analyzed as a completely randomized design using pen as the experimental unit. Feeding increasing levels of wheat DDGS quadratically increased dry matter intake (DMI) (P0.05). Feeding both wheat and corn DDGS increased (P=0.01) the excretion of nitrogen and phosphorus. Replacement of barley grain with up to 40% corn or wheat DDGS improved gain:feed and reduced days on feed, respectively with no detrimental effect on carcass quality grade or sub-primal boneless boxed beef yield. The results of this project also indicate that the inclusion of corn and wheat DDGS (up to 40%) in feedlot rations does not mitigate ruminal acidosis, however the inclusion of both byproducts strongly impacts nutrient (crude fat, ADF, NDF, ADIN and NDIN) digestibility