Preliminary Observations on Chemical Changes of Rumen Ingesta with and without Urea

Summary 1. A comparison of the composition, of rumen contents and the ration fed in respect to dry matter, fiber, ether extract, ammonia nitrogen, non-protein nitrogen and total nitrogen has been made. 2. The level of total nitrogen and fiber found in the rumen material is distinctly higher than in the ration fed. 3. The level of total nitrogen (protein nitrogen) and crude fiber found in the rumen content increases slightly in the time between feeding, indicating a more or less selective removal of nitrogen-free extract due to its breakdown by bacteria or bacterial enzymes and its passage out of the rumen. 4. Urea nitrogen or ammonia nitrogen when ingested as 1 to 5 per cent of the dry matter of the ration disappeared from the rumen in 4 to 6 hours after feeding. Evidence for its conversion to protein nitrogen is presented. 5. A definite increase in the percentage of protein nitrogen of the rumen ingesta was produced by adding 5 per cent urea to a low nitrogen basal ration.