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 Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Mixner, J. P. Articles by Lennon, H. D. Search for Related Content PubMed Articles by Mixner, J. P. Articles by Lennon, H. D., Jr.

Efficiency of Absorption of Thyroxine in Various Forms from the Gastrointestinal Tracts of Lactating Cows^{1, 2,}

Department of Dairy Science, New Jersey Agricultural Experiment Station, Sussex

ABSTRACT

The efficiencies of absorption of orally administered crystalline L-thyroxine, thyroprotein, and thyroglobulin from the gastrointestinal tract of lactating cows were estimated by comparing the relative increase of plasma protein-bound iodine (PBI) from oral administration of these materials, with the corresponding PBI increases due to intravenous administration of L-thyroxine.

In seven lactating cows the mean efficiency of absorption of thyroxine from thyroprotein (1.06% L-thyroxine) was 12.3%. Duplicate trials of absorption efficiency were performed in six other cows, the mean absorption efficiency being 13.9%; animal effects were highly significant statistically.

Five lactating cows were used to determine the absorption efficiency of crystalline L-thyroxine and thyroxine in porcine thyroglobulin concentrate (0.37% L-thyroxine). Again, highly significant differences were found among animals. The mean absorption efficiencies of the crystalline L-thyroxine and the thyroxine from thyroglobulin were 11.6 and 15.9%, respectively.

These results suggest that one of the important causes of animal variation in their lactational (or other) responses to orally administered thyroidal materials may be the efficiency with which the materials are absorbed from the digestive tract.

¹ Paper of the Journal Series, New Jersey Agricultural Experiment Station, Rutgers—The State University, New Brunswick.

² This study was part of a Northeast Regional Research Project (NE-30, The Relation of Certain Physiological Factors to the Productive Capacity of Dairy Cattle), a cooperative study involving agricultural experiment stations in the Northeastern Region and supported in part by regional funds of the United States Department of Agriculture.

A grant from the Cerophyl Laboratories, Inc., of Kansas City, for the partial support of this study is gratefully acknowledged.

³ Present address: G. D. Scarle & Co., P. O. Box 5110, Chicago 80, Illinois