Urea Inclusion in Distillers Dried Grains Supplements1

Two experiments evaluated the inclusion of urea in distillers dried grains supplements. In Exp. 1, 60 Angus heifers (278 ± 16 kg) were individually fed diets consisting of 58% ground corn cobs, 12% sorghum silage, and 30% distillers dried grains (DM basis) in Calan electronic gates. Urea replaced distillers dried grains at 0, 0.4, 0.8, 1.2, or 1.6% of diet DM. In Exp. 2, 48 crossbred heifers were fed meadow hay ad libitum and 1.4 kg (DM) distillers dried grains to which was added either 0 or 45 g urea/heifer daily. In both experiments, no response in animal weight gain or feed efficiency was observed when urea was added to the diet. Based on retrospective NRC (1996) model analysis of diets, metabolizable protein was in excess of requirements. Lack of response in animal performance may indicate lack of rumen degradable protein deficiency or sufficient N recycling to correct a rumen degradable protein deficiency. These studies indicate adding urea to distillers dried grains is not necessary when fed as a supplement in forage-based diets.