EFFECT OF ESTRADIOL-17-BETA AND TRENBOLONE ACETATE ON GROWTH, NITROGEN-RETENTION, AND UREA METABOLISM IN GOAT KIDS FED MILK

Effects of 5 mg estradiol-17 beta plus 30 mg trenbolone acetate on gro wth, N retention, and urea metabolism were studied in eight control an d eight male goat kids implanted at 21 days of age and hand-fed milk. N balance was measured over a 5 day period beginning 16 and 26 days (P eriods 1 and 2, respectively) after treatment. There was no significan t effect of anabolic agents on BW and growth rate during the trial. Du ring Period 1, treated kids decreased N intake significantly (P < 0.05 ), and tended to increase N retention (P < 0.10) due to a significant reduction (P < 0.01) in N and urea excreted in urine. Differences in N intake, N excreted in urine and N retention were not significant 4 we eks after treatment. Urea metabolism evaluated by the determination of urea transfer rates between body pools after an injection of a pulse dose of urea (130 mg kg(-1) BW) on the last day of Period 2 was not al tered by treatment, but kids with the greatest N retention had the low est rates of transfer of urea. It was concluded that, though the modif ications of N metabolism in kids implanted with anabolic agents at 21 days of age are transient, the use of these agents could be valuable, either in maintaining high ADG despite reduced N intake, or in countri es where protein availability for animal diets is limited or expensive .