A Study of Feeding Low Levels of Thyroprotein to Dairy Cows for a Period of Fifty-Two Weeks

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Abstract
Thyroprotein in the form of iodinated casein fed at levels of 0.625, 1.25 and 5 g. daily to dairy cows with a T.D.N. intake of 125% of Morrison''s Standards for good cows under usual conditions produced no significant stimulation of milk production, milk fat production, heart rates, respiration rates or body temps. Gains in body wt. and breeding efficiencies were not affected significantly. These same levels of thyroprotein feeding accompanied by a T.D.N. intake of 110% of Morrison''s Standards for good cows under usual conditions produced increases in milk production which approached statistical significance. Milk production appeared to decline when thyroprotein was withdrawn from the ration. Mean milk fat %, body wts., heart rates, respiration rates, body temps. and breeding efficiencies were 24012-24020 not affected significantly by these levels of thyroprotein admn.