FATE OF TRITIATED CHOLECALCIFEROL IN HEALTHY SHEEP AND IN THOSE AFFECTED BY OSTEODYSTROPHY

Abstract

Eight wethers which were affected by an osteodystrophic condition and raised in total confinement (group A) and five healthy wethers which were born and raised in a conventional barn with free access to an exercise yard (group B) were administered a single dose (50 μCi/animal) of tritiated cholecalciferol intraruminally (IR). Five more healthy wethers born and raised as those in group B received a single dose of the same amount of radioisotope intramuscularly (IM). Blood plasma, urinary and faecal radioactivities were measured for 96 h after administration of the isotope; at the end of this period, the animals were killed and tissue uptake of tritium was determined. Higher radioactivity was recorded at all times in the plasma of sheep dosed IM than in the plasma of sheep dosed IR. Tissue uptake of tritium was greater in sheep affected by osteodystrophy than healthy sheep. Higher radioactivity concentration was found in the tissues of animals dosed IM than those dosed IR. Total urinary clearance of radioactivity (lipid fraction) was higher in sheep which had bone dystrophy than in healthy sheep. Total faecal excretion of radioactivity was higher in the IR dosed sheep than in those treated IM.