title: Dependence of thyroxine utilization rate on dietary composition.
abstract: 1. The rate of utilization (k) of labelled thyroxine increased when energy intake, given as standard pig meal, was doubled from 20 to 40 g/kg body-weight per d. When the bulk of food was increased, but not its energy content, the value of k did not change. Ambient temperature was constant throughout the experiment. 2. Groups of pigs were given pig meal at 20 g/kg body-weight, 40 g/kg body-weight or 20 g/kg body-weight plus a supplement. The supplement was of equivalent energy content to 20 g pig meal/kg body-weight and consisted of coconut (high-fat), fish meal (high-protein) or glucose. The values of k were similar on diets (g/kg body-weight) of 40 pig meal, 20 pig meal plus coconut, and 20 pig meal plus fish meal. When the supplement was glucose however the values of k were similar to that for 20 g pig meal/kg body-weight. 3. The plasma concentrations of T4, and triiodothyronine were not affected by eating a meal, or by changing the energy intake presented as pig meal. A comparison between pigs given 20 g pig meal/kg body-weight plus supplements of bran, coconut, fish meal or glucose revealed differences in the concentration of both hormones. When food was withdrawn for 5 d the concentrations of both hormones declined.
mesh_terms: D000818:Animals; D004032:Diet; D004043:Dietary Fiber; D002149:Energy Intake; D013552:Swine; D013974:Thyroxine / Q000378:metabolism*; D013997:Time Factors; D014284:Triiodothyronine / Q000097:blood
chemical_list: D004043:Dietary Fiber; D014284:Triiodothyronine; D013974:Thyroxine