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Prolongation of gestation and changes in maternal steroid hormone concentrations during cold exposure of sheep in late pregnancy

Published online by Cambridge University Press:  02 September 2010

Deborah E. Samson ,
J. Slee ,
G. E. Thompson ,
Jane A. Goode  and
A. P. F. Flint
Deborah E. Samson
Affiliation:
ARC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
J. Slee
Affiliation:
ARC Animal Breeding Research Organisation, West Mains Road, Edinburgh EH9 3JQ
G. E. Thompson
Affiliation:
ARC Institute of Animal Physiology, Babraham, Cambridge CB2 4AT
Jane A. Goode
Affiliation:
ARC Institute of Animal Physiology, Babraham, Cambridge CB2 4AT
A. P. F. Flint
Affiliation:
ARC Institute of Animal Physiology, Babraham, Cambridge CB2 4AT
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Abstract

In 40 ewes exposed to thermoneutral or cold environments during the last 5 to 6 weeks of pregnancy (experiment 1), and in 10 ewes treated in the same way during the last 3 to 9 days of pregnancy (experiment 2), cold exposure lengthened mean gestation times by 1·7 and 2 days respectively. This effect was statistically significant only in experiment 1. Blood samples were taken from the right atrium of ewes in experiment 2 and the concentrations of some hormones in the plasma were measured. Cortisol concentrations were higher in plasma from cold-exposed ewes than control ewes. Plasma progesterone concentrations were lower in cold-exposed ewes than control ewes during a period from 36 h before parturition to 36 h after parturition, but the changes in plasma total unconjugated oestrogens, 17a, 20o-dihydroxypregn-4-en-3-one and oestrogen sulphates were associated with parturition in the normal way.

The mechanism underlying the prolongation of gestation during cold exposure requires further investigation; events that precede the change of steroid production by the placenta at parturition are most likely to be involved.

Type
Research Article
Information
Animal Production , Volume 36 , Issue 1 , February 1983 , pp. 1 - 6
Copyright
Copyright © British Society of Animal Science 1983

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References

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