This is the first report of a metabolic conversion in animals of zearalenone to zearalanols. Zearalenone was labeled with deuterium by base-catalyzed isotope exchange. The labeled zearalenone, in the form of its β-cyclodextrin inclusion complex, was administered orally and intravenously to sheep. In addition to deuteriozearalenone glucuronide, analysis of the urine revealed the presence of deuteriated α- and β-zearalenol and α- and β-zearalanol glucuronides. No zearalanone was detected in the urine. The problem of cis−trans isomerization of zearalenone in the presence of sunlight is also discussed. Keywords: Zeranol; zearalanol; zearalenone; zearalenol; metabolism; residue; Fusarium; mycotoxin

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The efficacy and retention of prototype and commercial (Cosecure) soluble-glass boluses containing selenium, cobalt and copper and having a similar size, density and composition were evaluated in separate 12-month trials with sheep grazing low selenium pastures but with adequate cobalt and copper levels. In both trials, sheep confirmed by X-ray as containing a bolus grew at a significantly greater rate than control sheep. This was attributed to the correction of a selenium deficiency. Although liver copper, and liver and serum vitamin B12 levels were significantly greater in treated sheep than controls on some occasions, the differences were not as great or consistent as with blood selenium levels. The rate of bolus loss was high and in both trials, approximately 40% of the sheep had lost the bolus after 6 months. No prototype boluses were present after 12 months. Intact Cosecure boluses were recovered from 3 sheep out of 30 after 12 months whilst one animal contained a part bolus. The recovered boluses were approximately 45% lighter than when originally administered. Bolus loss did not appear to be due to complete dissolution. In sheep which had lost the bolus, blood selenium levels fell with a half-life of 43 +/- 10 days.

Two trials were undertaken with lambs grazing selenium deficient pasture to determine if copper would enhance liveweight and fleece-weight responses to selenium supplementation. In the first trial, lambs given selenium or selenium plus copper gained significantly more weight and had higher fleece-weights after 260 days than did control lambs or lambs given copper alone. Copper given alone or together with selenium had no significant effect on liveweight or fleece-weight when compared with control lambs and lambs that were given selenium alone respectively. This finding was confirmed in a second trial when growth and fleece-weights of selenium and selenium plus copper treated lambs were compared and no significant differences found. In both trials copper significantly raised liver copper levels. In selenium supplemented but not in selenium deficient sheep, copper significantly increased blood selenium levels.