The Utilization of Urea by Ruminants as Influenced by the Level of Protein in the Ration

Summary 1. The protein content of rumen ingesta showed a decided increase when the level of protein in the concentrate fed was increased to 24 per cent. 2. The rate of conversion of urea nitrogen to protein in the rumen decreased as the protein level of the rumen ingesta became greater than 12 per cent. 3. When the level of protein in the concentrate fed was increased to more than 18 per cent the rate and extent of conversion of added urea nitrogen to protein began to decrease. 4. When no linseed oil meal was added to the basal grain mixture (11.3 per cent protein), the added urea was utilized up to a level of 4.5 per cent (protein equivalent of 12 per cent) of the grain mixture.