The effects on glucose metabolism of feeding a high-urea diet to sheep

1. Sheep were given either a basal diet of 107 g crude protein (nitrogen X 6.25)/kg or the same diet to which urea was added to increase the crude protein content to 221 g/kg. Isotope-dilution techniques with [U-14C]glucose and [2-3H]glucose were used to measure various criteria of glucose metabolism. The plasma concentrations of urea and potassium were determined. The sheep were then given the alternative diet and the experiment was repeated. 2. Plasma K concentrations were decreased on feeding urea (P less than 0.05). 3. Plasma glucose concentrations were reduced on the urea treatment (P less than 0.05), while glucose space and metabolic clearance rate were not significantly reduced (P greater than 0.05). 4. Some implications for the feeding of non-protein-N to ruminants are discussed.