Nitrogen metabolism in Brahman cross, buffalo, banteng and Shorthorn steers fed on low-quality roughage

Title
Nitrogen metabolism in Brahman cross, buffalo, banteng and Shorthorn steers fed on low-quality roughage
Publication Date
1979
Author(s)
Moran, J B
Norton, B W
Nolan, John V
( 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
CSIRO Publishing
Place of publication
Australia
DOI
10.1071/AR9790341
UNE publication id
une:23382
Abstract
Urea metabolism was studied in Brahman cross, buffalo, banteng and Shorthorn cattle offered a low quality hay. Intravenous injections of [14C]urea and 51Cr-EDTA were used to determine the irreversible loss of urea from the plasma, the degradation of urea in the rumen and lower digestive tract, and the glomerular filtration rate. When species were compared at equal liveweights and nitrogen intakes, buffaloes had significantly higher (P < 0.05) plasma urea concentrations and rates of irreversible loss of urea carbon from plasma than the other species. There were no significant differences between species in urinary urea excretion. Urea degradation in the digestive tract was linearly related to the irreversible loss of urea, and the proportion of irreversible urea loss degraded was significantly (P < 0.05) lower in Shorthorn cattle (48%) than in the other species (73-91%). Shorthorn cattle reabsorbed urea from the glomerular filtrate with a lower efficiency (60%) than did the other species (85-94%). In Brahman cross, buffalo and banteng, plasma urea recycled to the rumen was a relatively constant amount (4.3 g nitrogen/d) and represented on average 39% of the urea degraded in all parts of the digestive tract. Urea degraded in the digestive tract increased linearly with increasing irreversible loss of urea from plasma. It was concluded that, despite significant differences between species in urea synthesis and degradation, there was little indication that these differences constituted a significant nitrogen conservation mechanism in any one species.
Link
Citation
Australian Journal of Agricultural Research, 30(2), p. 341-351
ISSN
1444-9838
0004-9409
1836-5795
1836-0947
Start page
341
End page
351

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