J. Anim Sci.
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J. Anim Sci. 1952. 11:693-699.
© 1952 American Society of Animal Science
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Observations on the Electrocardiograms of Cattle Fed Thyroprotein1

J. F. Sykes, J. W. Thomas and L. A. Moore

U. S. Department of Agriculture2

Abstract

IN recent years considerable experimental work has been done on the feeding of thyroprotein to dairy cows in an effort to define the conditions under which thyroidally active materials can be used to increase milk production. It has been demonstrated that, when a hyperthyroid state is induced in milking cows by feeding thyroprotein, it is usually accompanied by an increase in milk production. The effects of continued hyperthyroidism for a considerable portion of any one lactation or for several succeeding lactations on the longevity and general health of cattle fed thyroprotein are of interest if thyroprotein is to be introduced in dairy cattle feeding practices. If prolonged hyperthyroidism has deleterious effects in cattle it might be expected that some change in cardio-vascular function could be detected.

Several investigators have made electrocardiographic observations on dairy cattle in which some degree of hyperthyroidism was induced. (Ralston et al. (1940), Dyrendahl (1950), Thorbeck et al. (1948).) Although Blaxter (1945, 1946) did not obtain electrocardiograms, he observed arrhythmias, abnormal heart sounds and extrasystoles by auscultation in cows fed iodinated casein as well as in apparently normal cows.

Footnotes

1 The thyroprotein used in this work was Protamone, a product of Cerophyll Laboratories, Inc., Kansas City, Missouri, and was supplied through the courtesy of Dr. W. R. Graham, Jr.

2 Bureau of Dairy Industry, A.R.A., Washington, D. C.






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