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Circadian and ultradian rhythms of plasma thyroid hormone concentrations in lactating dairy cows

Circadian and ultradian rhythms of plasma thyroid hormone concentrations in lactating dairy cows JOEL BITMAN, STANISLAW K&IL, D. L. WOOD, AND ALAN M. LEFCOURT Milk Secretion and Mastitis Laboratory, United States Department of Agriculture, Agricultural Research Center, Livestock and Poultry Sciences Institute, Beltsville 20705; and Department of Animal Sciences, University of Maryland, College Park, Maryland 20742 Bitman, Joel, Stanislaw Kahl, D. L. Wood, and Alan M. Lefcourt. Circadian and ultradian rhythms of plasma hormone concentrations dairy . Am. J. Physiol. 266 (Regulatory Integrative Comp. Physiol. 35): R1797-R1803, 1994.-Circadian and ultradian rhythms of thyroxine and triiodothyronine were analyzed by radioimmunoassay on integrated 15-min blood samples collected for 48 h from six lactating dairy . Body temperatures were recorded every 1.4 min using radiotelemetry. The were housed in an environmental chamber at 19.0 t 0.5”C (lights on between 0700 and 2300 h), fed daily at 0900 h, and milked at 0800 and 2000 h. Mean concentrations of plasma triiodothyronine and thyroxine exhibited similar circadian rhythms with minima (0500-1300 h) and maxima (1700-0200 h) separated by 12 h. Triiodothyronine peaked 2 h before thyroxine. The thyroxine circadian rhythm preceded a circadian body temperature rhythm by 2 h. Superimposed on the circadian rhythm was an ultradian rhythm with a 90-min period that was 15-20% of http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png AJP - Regulatory, Integrative and Comparative Physiology The American Physiological Society

Circadian and ultradian rhythms of plasma thyroid hormone concentrations in lactating dairy cows

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Publisher
The American Physiological Society
Copyright
Copyright © 1994 the American Physiological Society
ISSN
0363-6119
eISSN
1522-1490
Publisher site
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Abstract

JOEL BITMAN, STANISLAW K&IL, D. L. WOOD, AND ALAN M. LEFCOURT Milk Secretion and Mastitis Laboratory, United States Department of Agriculture, Agricultural Research Center, Livestock and Poultry Sciences Institute, Beltsville 20705; and Department of Animal Sciences, University of Maryland, College Park, Maryland 20742 Bitman, Joel, Stanislaw Kahl, D. L. Wood, and Alan M. Lefcourt. Circadian and ultradian rhythms of plasma hormone concentrations dairy . Am. J. Physiol. 266 (Regulatory Integrative Comp. Physiol. 35): R1797-R1803, 1994.-Circadian and ultradian rhythms of thyroxine and triiodothyronine were analyzed by radioimmunoassay on integrated 15-min blood samples collected for 48 h from six lactating dairy . Body temperatures were recorded every 1.4 min using radiotelemetry. The were housed in an environmental chamber at 19.0 t 0.5”C (lights on between 0700 and 2300 h), fed daily at 0900 h, and milked at 0800 and 2000 h. Mean concentrations of plasma triiodothyronine and thyroxine exhibited similar circadian rhythms with minima (0500-1300 h) and maxima (1700-0200 h) separated by 12 h. Triiodothyronine peaked 2 h before thyroxine. The thyroxine circadian rhythm preceded a circadian body temperature rhythm by 2 h. Superimposed on the circadian rhythm was an ultradian rhythm with a 90-min period that was 15-20% of

Journal

AJP - Regulatory, Integrative and Comparative Physiology – The American Physiological Society

Published: Jun 1, 1994

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