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Threonine metabolism in sheep

2. Threonine catabolism and gluconeogenesis in pregnant ewes

Published online by Cambridge University Press:  09 March 2007

J. C. Macrae  and
A. R. Egan†
J. C. Macrae
Affiliation:
The Hill Farming Research Organisation, Bush Estate, Penicuik,Midlothian EH26 0PY, Scotland
A. R. Egan†
Affiliation:
The Hill Farming Research Organisation, Bush Estate, Penicuik,Midlothian EH26 0PY, Scotland
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Abstract

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1. The irreversible loss rate (ILR) of glucose, bicarbonate and threonine were determined in six twin- and triplet-bearing ewes on three occasions during the last 6 weeks of gestation.

2. Three of the ewes (group S) were given conventional rations of hay plus concentrates so that their blood ketone levels did not rise over this period. The other three ewes (group H) were given a fixed intake of hay throughout; their blood ketone levels rose, but remained at subclinical levels.

3. The results are presented in the form of three-pool open-compartment models for each period. There was an increase in the glucose ILR for both groups over the 6-week period, but the over-all increase (mean ± SE) was much greater (p < 0·001) in group S (35·1 ± 2·43 g carbon/d) than in group H (11·3 ± 1·28 g C/d). Similarly, increases in bicarbonate ILR were also higher in group S (161 ± 11·2 g C/d) than in group H (63 ± 21·7 g C/d). However, whereas with group S ewes, receiving supplementary feed, this increase was progressive throughout the 6 weeks, with the group H ewesthe increase which occurred over the last 3 weeks of gestation (56 ± 26·3 gC/d) was much greater than that which occurred over the preceding 3 weeks (7 ±4·7 g C/d). This pattern was also evident in the oxidation of glucose to CO2.

4. In contrast to the previously mentioned findings, neither threonine ILR nor the amount of threonine converted to glucose or catabolized to CO2 changed significantly over the 6-week period.

5. The results are discussed in the light of findings presented in the previous paper that the amount of threonine used in catabolic processes can alter if a glucose-only sinkis created in wether sheep.

Type
Paper on General Nutrition
Information
British Journal of Nutrition , Volume 49 , Issue 3 , May 1983 , pp. 385 - 393
Copyright
Copyright © The Nutrition Society 1983

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