Basal urinary excretion of purine derivatives in sheep

In ruminants duodenal purines,mainly derived from microbial nucleic acids, are catabolised and excreted in the urine as xanthine, hypoxanthine, uric acid and allantoin. The use of purine derivatives as an index of net microbial syntesis in the rumen requires a better understanding of the contribution of endogenus losses to total urinary excretion. Similar levels of basal excretion of purine derivatives has been determined in ruminants maintained by intragastric nutrition (Giesecke et al. 1984, Fujihara et al. 1987) and preruminants fed on liquid diets (Linberg, 1989). However, lower excretion of allantoin and uric acid were recorded when exogenous supply was reduced by fasting (Rys et al. 1975).