Abstract :
In this experiment, creatinine (C) excretion by sheep was measured when they were fed different diets at different levels of
intake. Creatinine excretion was not affected by the level of feed intake or the addition of salt to lucerne-based diets. However,
differences between individual animals were significant. Creatinine excretion was significantly affected by diets, which were
formulated by combining different amounts of lucerne chaff, oaten chaff and sorghum. Itwas also found that there were significant
diurnal changes in the ratios of purine derivatives to creatinine (PD:C) in 3 hourly urine samples when the animals were fed
either once or twice daily, but the average value for the PD:C ratio of any two urine samples taken 12 h apart was close to the
daily mean. The results of this experiment suggest that if separate determination of the creatinine excretion by individual animals
is made and the average value of the ratio of PD:C in two spot urine samples taken 12 h apart is used to predict PD excretion by
spot urine sampling, microbial nitrogen flow can be estimated more accurately than when a fixed value of creatinine excretion
is used for all animals and only a single urine sample is taken.
© 2005 Elsevier B.V. All rights reserved.
