Bovine serum thyroxine, prolactin, growth hormone, glucocorticoid, and thyroxine binding globulin response to thyroprotein [Feeding dairy cattle]

Twenty-one lactating Holstein cows were assigned randomly to groups of seven and received: (1) no treatment; (2) 15 g thyroprotein daily for 5 wk; or (3) 15 g thyroprotein daily for 13 wk. Combined averages for serum thyroxine of cows in thyroprotein groups increased linearly from a baseline of 54 n...

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Bibliographic Details
Published in:Journal of dairy science 1975-05, Vol.58 (5), p.703-708
Main Authors: Shaw, G H, Convey, E M, Tucker, H A, Reineke, E P, Thomas, J W, Byrne, J J
Format: Article
Language:English
Subjects:
Animals
Caseins - pharmacology
Cattle
Female
Glucocorticoids - blood
Growth Hormone - blood
Hormones - metabolism
Iodine - pharmacology
Lactation
Pregnancy
Prolactin - blood
Serum Globulins - metabolism
Thyroxine - blood
Thyroxine - pharmacology
Thyroxine-Binding Proteins - metabolism
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Summary:Twenty-one lactating Holstein cows were assigned randomly to groups of seven and received: (1) no treatment; (2) 15 g thyroprotein daily for 5 wk; or (3) 15 g thyroprotein daily for 13 wk. Combined averages for serum thyroxine of cows in thyroprotein groups increased linearly from a baseline of 54 ng/ml to a peak of 135 ng/ml at 6 days after thyroprotein feeding was begun. Serum thyroxine then decreased to approximately 80 ng/ml at 23 days of thyroprotein feeding which was maintained during the remainder of the feeding period. Following thyroprotein withdrawal from the diet serum thyroxine concentration decreased to 24 ng/ml at 6 days. Neither serum prolactin, growth hormone, nor total glucocorticoids were affected by thyroprotein feeding or withdrawal. Average milk production of cows in the control group decreased linearly with time. Milk production of cows fed thyroprotein for 5 wk averaged 2.2 to 3.3 kg/day more than cows in the control group and that of cows fed thyroprotein for 13 wk averaged .95 to 2.5 kg/day more than controls for 60 days, but between 60 and 91 days it was .9 kg/day less than controls.
ISSN:0022-0302
1525-3198
DOI:10.3168/jds.S0022-0302(75)84631-5