McKinnon, John2010-01-292013-01-042011-02-022013-01-042010-012010-01January 20http://hdl.handle.net/10388/etd-01292010-172749Two 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.en-USwheatcattleDDGScornfeedlot performancecarcass qualitytext