Blood-urea concentration in relation to protein utilization in the ruminant

It has been shown that under a given feeding régime the concentration of blood urea in the sheep is constant. 2. Changes in the diet lead to different levels of blood-urea concentration which can be correlated with different rumen-ammonia concentrations; the change in blood-urea concentration follows increases or decreases in rumen ammonia after a delay period of 4–8 hr. 3. Fluctuations in blood-urea concentration in the sheep are not primarily due to changes in the overall nitrogen intake. 4. It is suggested that these findings might form the basis of a supplementary test in assessing the value of the protein in a foodstuff for ruminants.