Severe experimental hyperthyroidism in the ruminant. I. Metabolic effects

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Abstract
SUMMARY: 1. Metabolism experiments have been made with five sheep fed iodinated casein in doses sufficient to give symptoms of hyperthyroidism, ranging from moderate to severe. Two comparable sheep were included to serve as controls.2. The same ration was used throughout each experiment, and it was found that the digestibility of its dry matter and of its crude protein content declined when the sheep were made hyperthyroid. This was due to increased peristalsis.3. The treated sheep lost body N when iodinated casein was given, the loss being proportional to dosage. Calculations indicated increases in the endogenous catabolism by up to 120%, and also increases in deamination.4. There was an increased excretion of urea and ammonia during hyperthyroidism, the latter being associated with a decrease in the plasma carbon dioxide combining capacity.5. Purine catabolism was accelerated by more than 50% in some sheep. Starvation of one sheep did not depress nucleoprotein catabolism as it does in the normal sheep.