Effects of methyl-thiouracil on liver vitamin A, spermatogenesis and calcium metabolism of merino rams

Abstract

It has been suggested that in north-western Queensland hot weather depresses the activity of the thyroid and thus reduces the efficiency of conversion of the small amount of available carotene. This could produce a vitamin A deficiency, which in turn might affect the thyroid and so set up an adverse cycle (Moule, 1950). The experiment reported here was designed to test this hypothesis. Facilities for simulating the temperatures of north-western Queensland were not available, so methyl-thiouracil was used to depress the activity of the thyroid.