The digestibility of carotene by the cow and the goat as affected by thyroxine and thiouracil

Abstract

Subjection of lactating cows to a diet free from carotene reduced fecal carotene to a trace in 6-8 days. Reinstatement of the carotene regime caused a rapid reappearance of fecal carotene. Reappearance of fecal carotene after reinstatement of the carotene-containing diet was made markedly earlier by thiouracil and markedly later by thyroxine. The digestability of carotene by both cows and goats was markedly increased by thyroxine and markedly reduced by thiouracil. Goats digested carotene more efficiently than did cows. The increase of digestibility of carotene resulting from thyroxine treatment was greater in the cows than in the goats. Conversely, the decrease due to thiouracil was greater in the goats than in the cows.