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Thyroxine and wool follicle activity

Published online by Cambridge University Press:  02 September 2010

M. L. Ryder
M. L. Ryder
Affiliation:
ARC Animal Breeding Research Organization, West Mains Road, Edinburgh EH9 3JQ
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Abstract

Serum thyroxine levels were observed in 15 Soay ewes and seven rams for 1 year. From June to November the ewes had thyroxine concentrations 40% higher than the rams, and the level in both sexes increased from December to May, demonstrating a seasonal cycle in thyroxine level that could be associated with the annual wool growth cycle. To hasten the onset of wool follicle activity, nine Wiltshire sheep were given thyroxine implants in autumn when the follicles normally become inactive, but only a slight increase in follicle activity occurred. Eighteen Soay sheep were given thiouracil orally for 1 month in spring in an attempt to block a possible seasonal increase in thyroxine secretion that might be associated with the normal regrowth of wool, but no retardation of the spring regrowth was obtained.

Type
Research Article
Information
Animal Production , Volume 28 , Issue 1 , February 1979 , pp. 109 - 114
Copyright
Copyright © British Society of Animal Science 1979

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References

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