NATURAL ZERANOL (ALPHA-ZEARALANOL) IN THE URINE OF PASTURE-FED ANIMALS

Zeranol and its epimer taleranol have been found in the urine of pasture-fed animals; There were similar distributions in samples from slaughterhouses and in samples from an untreated trial group. Amounts ranged up to 1 ng/mL for deer, goats, and lambs, 2.1 ng/mL for sheep, 13 ng/mL for cattle, and 19 ng/mL for horses. The zeranol and taleranol were naturally present and were most likely derived from Fusarium species known to be present in New Zealand pasture. It is not known whether zeranol and taleranol were directly produced by Fusarium or produced by reduction of the Fusarium metabolite zearalenone inside the animals. For horses and cattle, the amounts found were typical of those expected from treatment with RALGRO, a zeranol-containing implant. The levels found imply that xenobiotic anabolic compounds at physiologically effective levels can occur in domestic animals without deliberate treatment.