Abstract
A series of eight experiments was conducted to study the metabolism of biuret and urea in sheep. Biuret−14C was administered to the sheep by either intravenous or intraruminal injection. Urea−14C or sodium bicarbonate−14C was administered intraruminally. Ninety-five percent of the 14C of intravenously-injected biuret−14C was recovered in urine. Expired 14CO2 collected over an 8 hr. period contained 1.4% of the 14C. Approximately 2.5% of the 14C was present in the rumen 8 hr. after injection. The data indicated that biuret was not utilized directly by animal tissues. The maximum recovery of 14C in expired 14CO2 from intraruminally-injected biuret−14C or urea−14C was 28.5 and 25.1%, respectively, for periods up to 7 hr. Negligible amounts of 14C were recovered in feces. Urine did not contain more than 3% of the 14C from biuret−14C or urea−14C. Less than 50% of the 14C injected intraruminally as biuret−14C or urea−14C was accounted for in all samples measured, including estimates of the activity in the rumen and in blood plasma. In contrast, nearly 100% of the 14C of sodium bicarbonate−14C was recovered in expired CO2 within 6 hr. Results suggested that the carbon of biuret and urea did not equilibrate with the CO2 pool. Failure to achieve equilibration suggested that biuret and urea were metabolized in the rumen without complete hydrolysis to CO2 and NH3. Copyright © 1968. American Society of Animal Science . Copyright 1968 by American Society of Animal Science