EFFECT OF ENERGY INTAKE ON HEART RATE IN HYPERTHYROIDISM INDUCED BY FEEDING THYROPROTEIN

Abstract

The interaction between energy intake and thyroprotein on heart rate was studied using 5 dairy steers. Two of the steers were fed thyroprotein on a body wt. basis during periods when their feed allotments were varied as to % of their calculated energy requirements. Another pair of steers were given similar amts. of feed during the same periods without added thyroprotein, and a 5th steer was kept on a relatively constant intake over the whole exptl. period. Direct proportional changes in heart rate occurred as a result of alternations in energy consumption or as a result of feeding thyroprotein at different levels of energy intake. The heart rate of the thyroprotein-induced hyperthyroid steers was materially altered by varying the feed intake. The amt. of feed consumed did not alter the essential activity of thyroprotein on heart rate. The effects of thyroprotein and energy seem to be additive.