Selenium levels in the blood, liver, kidney and muscle of sheep after the administration of iron/selenium pellets or soluble-glass boluses.
Slow-release devices composed of elemental selenium and iron or a soluble-glass containing selenium, cobalt and copper were effective in significantly raising blood and tissue selenium levels of sheep at pasture. Three out of six animals given a soluble-glass bolus lost them over the four months of the trial. In contrast, all six animals retained their iron-selenium pellets. Selenium levels in the kidney cortex four months after administration of the devices, when peak levels were most likely to occur, were approximately 12.7 micromol/kg (1mg/kg). This value is 50% of the maximum permitted level in edible tissue in New Zealand. There was no obvious pattern of distribution of selenium throughout the liver. Variations in concentration from one site to another were, in some cases, almost two-fold. Therefore the analysis of liver biopsy samples gives only an approximate assessment of the mean hepatic concentration.
Millar
K R
KR
Wallaceville Animal Research Centre, Research Division, Ministry of Agriculture and Fisheries, Private Bag, Upper Hutt, New Zealand.
Meads
W J
WJ