James C. MacDonald
Date of this Version
Linder, H.F. 2020. Interaction of urea with frequency and amount of distillers supplementation for growing steers on a high forage diet. University of Nebraska-Lincoln. M.S. Thesis.
Two studies were conducted to determine interactions of urea inclusion to a dried distillers grains plus solubles (DDGS) supplement fed at two amounts and two frequencies to steers on a high forage diet. In Exp. 1, 120 steers were fed individually for 84 d. Steers received ad libitum grass hay and 1 of 8 treatments. Supplement was fed either every day (D) or 3x/week (ALT), amount of supplement fed was 6.36 kg/week (LO) or 12.73 kg/week (HI), and contain either no urea (-U) or 1.3% urea (+U). Hay DMI and steer BW were measured. In Exp. 2, 8 ruminally cannulated steers were used in a digestion trial for 6 periods. Treatment design was the same as Exp. 1, except that supplement was fed at a rate of 0.4% of BW (LO) or 0.8% of BW (HI). Hay DMI, rumen fluid, in situ NDF disappearance, and rumen pH were measured. In Exp. 1, ADG was only affected by amount of supplement with steers on HI gaining more than LO. Hay DMI was reduced by increased amount of supplement and by decreased frequency of supplementation. In Exp. 2, hay DMI was also reduced due to increase amount of supplement and decreased frequency of supplementation. Rumen pH was decreased on the day of feeding for steers on ALT and reduced for steers fed HI vs LO. There was an interaction of urea x amount for rumen ammonia-N concentration but no effect of frequency. A reduction in in situ NDF disappearance was observed on the day ALT received supplement between HI and LO. There was no difference between NDF digestibility between D and ALT. Infrequent supplementation of DDGS results in no difference in ADG. No effect was seen of with the inclusion of urea and animal performance was only improved when increase the rate of DDGS supplementation. There is little change in rumen fermentation parameters between frequency of supplement feeding, indicating that forage digestion is not impacted by supplementation frequency. Thus, DDGS can be supplemented infrequently without reducing animal performance.
Advisor: James C. MacDonald