HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Nixon, D. A. Articles by Anderson, R. R. Search for Related Content PubMed PubMed Citation Articles by Nixon, D. A. Articles by Anderson, R. R.

Free and Total Thyroid Hormones in Serum of Holstein Cows¹

Department of Dairy Science, University of Missouri, Columbia 65211

ABSTRACT

Basic parameters are reported for free thyroxine and triiodothyronine in blood serum of dairy cattle. Free thyroxine ranged from a low of 1.47 ng/dl in the summer to 1.86 ng/dl in the spring and from 1.37 ng/dl in early lactation to 1.85 ng/dl in midlactation. The average free triiodothyronine went from a low of 2.98 pg/ml in winter to a high of 6.23 pg/ml in the fall and from 3.45 pg/ml in early lactation to 5.37 pg/ml in midlactation. The free fraction of the serum compared with the total fraction averaged .0267% for thyroxine and .291% for triiodothyronine. Free and total thyroxine were high in fall, low in winter, and intermediate in spring and summer. Free and total triiodothyronine showed a similar pattern with a greater magnitude in the variations. Even though the thyroid hormone secretion rate was higher in winter (earlier studies), increased tissue utilization kept serum concentrations low. Free and total thyroxine and triiodothyronine were low in early lactation due to high demands from peak milk production. Stage of lactation had a much greater influence on changes in serum thyroid hormones than did season.

¹ Contribution from the Missouri Agricultural Experiment Station, Journal Series Number 10193. Approved by the Director. This study was supported in part by a grant from the Libyan Government.

This article has been cited by other articles:

				H. Guyot, J. Sulon, J.-F. Beckers, J. Closset, P. Lebreton, L. Alves de Oliveira, and F. Rollin Development and validation of a radioimmunoassay for thyrotropin in cattle J Vet Diagn Invest, November 1, 2007; 19(6): 643 - 651. [Abstract] [Full Text] [PDF]