Auto-condensation products of urea

Process for producing a partuculate mixture of auto-condensation products of urea containing predominantly biuret which is suitable as a non-protein nitrogen supplement for ruminant feeds comprising heating at a temperature between 150.degree.C and 180.degree.C with continuous stirring in a reaction vessel having a smooth surface, finely divided urea dispersed in a non-toxic branched chain paraffin which is inert to urea and its auto-condensation products, has a boiling point in the range of 150.degree. and 180.degree.C and in which urea or its auto-condensation products have a solubility at ambient temperature of not more than 5% by weight of the urea of its auto-condensation products, said paraffin containing a non-toxic surface active agent selected from the group consisting of cationic surface active agents, nonionic surface active agents, anionic surface active agents and mixtures of cationic and anionic surface active agents in an amount of from 0.01 to 1.0 percent m/m of the initial quantity of urea, continuing said heating until at least 90 percent of the urea is converted into said mixture of auto-condensation products and separating the particulate mixture thus formed from the branched chain paraffin.