Input of Endogenous Protein Into the Forestomachs of Sheep

The input of endogenous protein into the forestomachs of sheep given bromegrass pellets was calculated as 8.1–10.8 g N/day by reference to previously published 15 N-tracer studies. Approximately 1.3 g N/day of this amount was attributed to salivary protein entering the rumen, with 6 g N/day apparently derived from sloughing of the rumen epithelium. The need for consideration of endogenous N inputs into the forestomachs of ruminants in schemes for assessment of N requirement is discussed.