337 Effect of adding urea to finishing diets containing two different inclusions of distillers grains on steer performance and carcass characteristics

摘要

Crossbred beef steers (n = 384) were utilized to evaluate the effects of adding urea to a dry rolled corn based finishing diet containing low inclusions of wet distillers grains plus solubles (WDGS). Treatments were set up as a 2 × 4 factorial arrangement with factors consisting of WDGS inclusion at either 12 or 20% of diet dry matter (DM) and urea inclusion at either 0, 0.4, 0.8, 1.2% of diet DM. Cattle were blocked and stratified by initial body weight (BW) and assigned randomly to treatment. The heavy block of cattle were harvested after 160 d on feed (DOF) and the middle and light blocks of cattle were harvested after 179 DOF. The model include the fixed effects of weight block, WDGS inclusion, urea inclusion, and their interactions. There were no significant interactions (P > 0.12) observed between WDGS inclusion and urea inclusion in the diet; therefore, only main effects are discussed. Increasing inclusion of WDGS improved (P < 0.04) carcass adjusted ADG and G:F. Dry matter intake was reduced (P = 0.04) with increasing WDGS inclusions. Fat thickness was increased (P = 0.04) with increased WDGS inclusion; however, no other carcass characteristics were significantly affected by WDGS inclusion. Cubic effects of urea inclusion were observed (P < 0.05) for HCW, final BW, ADG, and DMI on a carcass adjusted and live BW basis; however, cubic effects with increasing urea inclusion are of minimal biological relevance. There were no linear or quadratic responses (P > 0.11) for increasing urea inclusion in the diet for performance measurements or carcass characteristics. Increasing WDGS inclusion in the diet improved performance. Added urea in the diet had minimal impact on performance, regardless of wet distillers grains plus solubles inclusion.