Hostname: page-component-7c8c6479df-27gpq Total loading time: 0 Render date: 2024-03-29T13:35:06.585Z Has data issue: false hasContentIssue false

The efficacy of protein supplementation in overcoming urea toxicity in sheep

Published online by Cambridge University Press:  25 March 2008

E. Payne
Affiliation:
Animal Research Institute, Department of Primary Industries, Yeerongpilly, Queensland 4105, Australia
L. Laws
Affiliation:
Animal Research Institute, Department of Primary Industries, Yeerongpilly, Queensland 4105, Australia
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

1. In the first experiment sheep taken from pasture were given a low-protein diet for 6 weeks in individual pens. Then, for 1 week, groups were given a supplement of lucerne chaff, safflower meal or lucerne chaff plus safflower meal. In the second experiment eighteen sheep maintained on lucerne chaff rather than pasture were then depleted of protein to a greater extent by feeding on a restricted low-protein diet. Six of the sheep received a supplement of molasses throughout the period of protein depletion while six of the sheep on the basal ration received a supplement of safflower meal after 6 weeks on the low-protein diet.

2. The urea tolerance of the sheep, as indicated by blood ammonia levels after oral dosing with aqueous solutions of urea, was determined after the period of supplementation. ‘Arginine synthetase’ activity (combined activities of argininosuccinate synthetase (EC 6.3.4.5) and argininosuccinate lyase (EC 4.3.2.1)) was determined in liver samples obtained by biopsy at various intervals during the experiment.

3. Supplementation for 7 d with 73 g crude protein (nitrogen × 6.25)/d increased the tolerance to urea, as indicated by reduced blood NH3 levels, and also increased ‘arginine synthetase’ activity.

4. Giving supplements of molasses delayed the onset of urea toxicity but not the extent of toxicity.

5. It is suggested that short-term feeding of protein concentrates to sheep before giving urea supplements can increase their tolerance to urea.

Type
Papers on General Nutrition
Copyright
Copyright © The Nutrition Society 1976

References

Austin, J. (1967). In Urea as a Protein Supplement, p. 180 [Briggs, M. H., editor]. Oxford: Pergamon Press.Google Scholar
Brown, G. W. & Cohen, P. P. (1959). J. biol. Chem. 234, 1769.CrossRefGoogle Scholar
Dick, A. T. (1952). Aust. vet. J. 28, 234.CrossRefGoogle Scholar
Giles, K. W. & Myers, A. (1965). Nature, Lond. 206, 93.CrossRefGoogle Scholar
Lewis, D. (1957). J. agric. Sci., Camb. 48, 438.CrossRefGoogle Scholar
Miller, G. L. (1959). Analyt. Chem. 31, 964.CrossRefGoogle Scholar
Morris, J. G. & Payne, E. (1970). J. agric. Sci., Camb. 74, 259.CrossRefGoogle Scholar
Munro, H. N. & Fleck, A. (1966). Meth. biochem. Analysis 14, 113.CrossRefGoogle Scholar
Payne, E. & Morris, J. G. (1969). Biochem. J. 113, 659.CrossRefGoogle Scholar
Schimke, R. T. (1962). J. biol. Chem. 237, 459.CrossRefGoogle Scholar
Schimke, R. T. (1963). J. biol. Chem. 238, 1012.CrossRefGoogle Scholar
Seligson, D. & Seligson, H. (1951). J. Lab. clin. Med. 38, 324.Google Scholar
Tagari, H., Krol, O. & Bondi, A. (1965). Nature, Lond. 206, 37CrossRefGoogle Scholar