Effect of Dried Distillers Grain Supplementation on Forage Intake, Digestibility, and Rumen Parameters in Steers Consuming Bermudagrass Round Bale Silage

Eight ruminally fistulated steers were utilized to evaluate the effects of amount of dried distillers grains (DDG) supplementation on forage dry matter intake (DMI), digestibility, and rumen parameters in steers consuming bermudagrass round bale silage (RBS). Treatments consisted of RBS only or RBS plus daily supplementation of DDG at 0.33, 0.66, or 1.0% of bodyweight (BW). There was quadratic response to the amount of DDG supplemented on RBS DMI. The greatest RBS DMI occurred in steers fed the 0.33% DDG and the least at the 1% DDG inclusion. Steers consuming only RBS had the least total DMI (18.28 lb/d; P < 0.01), whereas steers supplemented with DDG at 1% of BW had the greatest total DMI (26.66 lb/d). Total tract apparent dry matter digestibility (TTADMD) also increased in a quadratic manner (P < 0.05) as amount of DDG supplement increased. In addition, steers consuming DDG+1.0 had a tendency to have increased TTADMD compared to steers consuming DDG+0.33 (60.7 vs. 52.9%, respectively). The increase in TTADMD is likely a reflection of the DDG being more digestible than the RBS, which is of moderate quality. Mean pH values responded in a quadratic manner as DDG amount increased mean pH values decreased. Steers fed RBS had greater pH (P < 0.05; 6.42) compared to RBS+0.33 (6.26), RBS+0.66 (6.15), and RBS+1 (6.28). Rumen NH3-N concentrations tended to respond in a cubic manner as DDG supplementation increased in the diet. Steers consuming RBS had decreased (P < 0.05; 25.45 mg/dL) mean rumen NH3-N compared to steers consuming RBS+0.66 (33.01 mg/dL) and RBS+1 (33.20 mg/dL). Supplementing DDG up to 1% of BW in the diet depressed RBS intake through a substitution of DDG for RBS. Increasing DDG offer depressed ruminal pH for a discreet amount of time, however supplementing DDG up to 1% of BW increased total DMI, TTADMD, and rumen NH3-N.