title: Sulphur-selenium studies in sheep. I. The effects of varying dietary sulphate and selenomethionine on sulphur, nitrogen and selenium metabolism in sheep.
abstract: Sulphur, selenium and nitrogen metabolism were studied in Merino wethers fed for 35-day periods on semipurified diets in which the sulphur content was increased to either 0-07 or 0-20% by the addition of sodium sulphate. At both levels of sulphur, additions of selenium as DL-selenomethionine increased the basal level of selenium (0-02 microgram/g) to 0-06, 0-09 and 0-67 microgram/g. Both levels of dietary sulphur supported positive sulphur balances but a reduction in sulphur intake per se resulted in a significant depression in dry matter digestibility (P less than 0-05), apparent nitrogen digestibility (P less than 0-05), nitrogen balance (P less than 0-01), sulphur balance (P less than 0-05) and plasma sulphate-sulphur (P less than 0-05) and wool (P less than 0-01) selenium levels. Selenium balance was not affected by differences in sulphate-sulphur intake. Selenium balances (P less than 0-001), plus the selenium levels in plasma (P less than 0-001), and wool (P less than 0-001) were significantly different at the different levels of selenium supplementation. A positive selenium balance was achieved when the selenium intake was approximately 37 microgram/day, regardless of sulphur treatment. The validity of using plasma and/or wool selenium levels as indices of the selenium status of sheep is questioned.
mesh_terms: D000818:Animals; D004032:Diet; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D012643:Selenium / Q000032:analysis / Q000378:metabolism*; D012645:Selenomethionine / Q000008:administration & dosage; D012756:Sheep / Q000378:metabolism*; D013431:Sulfates / Q000008:administration & dosage*; D013455:Sulfur / Q000032:analysis / Q000378:metabolism*; D014935:Wool / Q000032:analysis
chemical_list: D013431:Sulfates; D013455:Sulfur; D012645:Selenomethionine; D012643:Selenium; D009584:Nitrogen