Urea-Nitrate Interrelationships in Sheep under Feedlot Conditions

Two experiments were conducted to study nitrate-urea interrelationships, and a third was conducted to compare the utilization of soybean meal, urea and nitrate when added to a low-protein ration. All experiments utilized lambs fed corn and corn silage rations under feedlot conditions. In two experiments, sodium nitrate (2.5% of ration, air-dry basis) tended to reduce weight gains when fed in rations with soybean meal (7%, air-dry basis) but it had only a slight effect in rations with an equivalent amount of crude protein from urea (1%, air-dry basis) where gains were already below those of the lambs fed soybean meal. In these instances, lambs fed urea gained 16.5 to 19.5% less than lambs fed soybean meal. No evidence was obtained to support a nitrate-urea inter-relationship. In a third experiment, the crude protein content of an 8.04% protein ration was increased to 9.54% using soybean meal, urea or sodium nitrate to furnish equivalent amounts of nitrogen. Under these conditions the three nitrogen sources were utilized equally well as sources of crude protein.