195 Interaction of Urea with Frequency and Amount of Distillers Grains Supplementation for Growing Steers on a High Forage Diet

Abstract

Abstract Two studies determined the interactions of urea inclusion to a dried distillers grains plus solubles (DDGS; 29.4% CP, 5.48% ether extract) supplement fed at 2 amounts and 2 frequencies to steers consuming ad libitum Smooth Bromegrass hay (6.8% CP). In Exp. 1, 120 (247 kg; SD = 20) steers were fed individually for 84 d with treatments arranged in a 2 x 2 x 2 factorial. Supplement was fed every day (D) or 3x/week (ALT), amount of supplement fed was 6.36 kg/week (LO) or 12.73 kg/week (HI) and contained either no urea (-U) or 1.3% urea (+U). In Exp. 2, 8 ruminally cannulated steers (310 kg; SD = 25) were used in an 8 x 6 row-column design with 8 steers and 6, 14-d periods. Treatment design was the same as Exp. 1, except that supplement was fed at a rate of 0.4% (LO) or 0.8% of BW (HI) and supplement was fed either daily (D) or every other day (ALT). In Exp. 1, ADG was 0.30 kg/d greater, and hay DMI was reduced by 0.39 kg/d for HI vs. LO (P < 0.01). Hay DMI was reduced by 0.54 kg/d for ALT vs. D (P < 0.01). In Exp. 2, hay DMI was also reduced HI vs. LO (P < 0.01). Rumen pH was decreased on the day of feeding for steers on ALT (P < 0.01) and was reduced for steers fed HI vs. LO. A reduction in in situ NDF disappearance was observed on the day ALT received supplement between HI and LO (P < 0.01). However, there was no difference between NDF digestibility between D and ALT (P > 0.05). Urea had no effect on digestion or ADG, suggesting RDP was not deficient. Dried distillers grains can be supplemented infrequently without reducing animal performance.