Evaluation of the Addition of Urea to Finishing Diets Containing Distillers Grains and Yeast Extracted Condensed Distillers Solubles on Finishing Performance of Beef Cattle

Three feedlot experiments evaluated the effects of added urea to finishing diets containing less than 20% WDGS. In Exp.1, a significant interaction was observed for G:F between urea concentration and distillers concentration in the diet. Feeding urea in diets with 10% WDGS had no significant impact on animal G:F. Urea included in diets with 15% WDGS had a quadratic impact on G:F with urea included at 0.5% of diet DM having the greatest performance. When adding urea to diets containing 20% WDGS, a quadratic impact on G:F was observed where urea included at 0.5% of diet DM reduced G:F. In Exp. 2 there were no interactions between urea concentration and WDGS concentration. Increasing concentration of WDGS in the diet improved G:F by 4.7%. The addition of urea to the diet had minimal impact on performance although cubic effects of urea inclusion were observed suggesting variation in the data. For Exp. 3 no difference was observed, for either urea concentration or WDGS concentration in the diet, however, DMI was reduced when urea was included in the diet at 1.2%. Two experiments evaluated the effects of the addition of yeast extracted solubes (EXP) and yeast to finishing diets on performance, carcass characteristics, and nutrient metabolism. In Exp. 1, feeding increased EXP in the diet resulted in quadratic effects on performance with what appears as a linear decrease up to 15% EXP is included followed by a dramatic increase at 20% inclusion. Feeding similar concentrations of EXP when compared to conventional condensed distillers solubles (CONV) reduced animal performance. However, when yeast (YST) was added back to the EXP, performance is similar to CONV. Adding YST alone does not improve performance over the corn control. All concentrations of EXP and CONV performed worse than the corn control. In Exp. 2 no effects on measured nutrient digestibility were observed. However, DM intake and excretion were affected with tendencies for OM, NDF, ADF, and starch intakes to be affected. Digestible energy intake in Mcal/kg and TDN were affected by diet and appeared to follow similar patterns as the performance trial perhaps explaining the observed performance response.