Measurement of endogenous allantoin excretion in sheep urine

Urinary allantoin, an end product of purine base metabolism, originates in sheep from three possible sources: exogenous, purine bases of rumen microorganisms and feed purines and ureides, and endogenous, purines catabolized in tissue turnover. Earlier studies suggested that nucleic acid purines of rumen micro-organisms may be a predominant source of urinary allantoin (Antoniewicz, Heinemann & Hanks, 1979, 1981).