Urinary excretion of purine derivatives as an index of microbial protein synthesis in the camel ('Camelus dromedaries')

Title
Urinary excretion of purine derivatives as an index of microbial protein synthesis in the camel ('Camelus dromedaries')
Publication Date
2004
Author(s)
Guerouali, Abdelhai
Gass, Youssef
Balcells, Joaquim
Belenguer, Alvaro
Nolan, John Vivian
( author )
OrcID: https://orcid.org/0000-0001-7949-950X
Email: jnolan@une.edu.au
UNE Id une-id:jnolan
Type of document
Journal Article
Language
en
Entity Type
Publication
Publisher
Cambridge University Press
Place of publication
United Kingdom
DOI
10.1079/BJN20041208
UNE publication id
une:3847
Abstract
Five experiments were carried out to extend knowledge of purine metabolism in the camel ('Camelus dromedarius') and to establish a model to enable microbial protein outflow from the forestomachs to be estimated from the urinary excretion of purine derivatives (PD; i.e. xanthine, hypoxanthine, uric acid, allantoin). In experiment 1, four camels were fasted for five consecutive days to enable endogenous PD excretion in urine to be determined. Total PD excretion decreased during the fasting period to 267 (SE 41·5)μmol/kg body weight (W)0.75 per d. Allantoin and xanthine + hypoxanthine were consistently 86 and 6·1% of total urinary PD during this period but uric acid increased from 3·6% to 7·4%. Xanthine oxidase activity in tissues (experiment 2) was (μmol/min per g fresh tissue) 0·038 in liver and 0·005 in gut mucosa but was not detected in plasma. In experiment 3, the duodenal supply of yeast containing exogenous purines produced a linear increase in urinary PD excretion rate with the slope indicating that 0·63 was excreted in urine. After taking account of endogenous PD excretion, the relationship can be used to predict purine outflow from the rumen. From the latter prediction, and also the purine:protein ratio in bacteria determined in experiment 5, we predicted the net microbial outflow from the rumen. In experiment 4, with increasing food intake, the rate of PD excretion in the urine increased linearly by about 11·1 mmol PD/kg digestible organic matter intake (DOMI), equivalent to 95 g microbial protein/kg DOMI.
Link
Citation
British Journal of Nutrition, 92(2), p. 225-232
ISSN
1475-2662
0007-1145
Start page
225
End page
232

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