Abstract
Four steers were implanted in the ear with approximately 28 mg of 14C-diethylstilbestrol (14C-DES) and were slaughtered 30, 60, 90 or 120 days later. All urine and feces were collected from time of implantation until slaughter. Total recoveries of 14C from excreta and tissues ranged from 82.7 to 90.9% of 14C implanted (avg 86.8%). The percentages of implanted 14C remaining in the ears were 65.9, 27.3, 30.0 and 4.2 at 30, 60, 90 and 120 days after implantation, respectively. Radioactivity was measurable in the plasma, urine and feces throughout the collection period for all steers. Total excretions (urine and feces) were 34.7, 56.8, 52.5 and 84.9% of the 14C implanted for steers killed at 30, 60, 90 and 120 days, respectively. Approximately twice as much was excreted in feces as in urine. The concentrations of 14C were similar in the livers, kidneys, lungs and salivary glands of all steers. In the livers, 15 to 33% of the 14C present was characterized by isotopic dilution as 14C-DES or a conjugate of DES (.07 to .13 ppb DES equivalents). Copyright © 1975. American Society of Animal Science . Copyright 1975 by American Society of Animal Science.