Effects of copper and molybdenum supplements on the copper and selenium status of pregnant ewes and lambs.

The aim of this work was to investigate whether Cu, alone or in combination with Mo, reduces the Se status of sheep. Thirty-six Hampshire ewes were separated prior to mating into four treatment groups of nine sheep each. The four groups consisted of 1) basal (alfalfa hay or legume-grass low-moisture silage, corn, oats), 2) basal plus 10 mg Cu/kg diet, 3) basal plus 10 mg Mo/kg and 4) basal plus Cu and Mo (each 10 mg/kg). Copper and Mo were added to both ewe and lamb diets. Treatments continued until lambs were weaned at 10 wk postpartum. The basal ewe diet contained, in mg/kg, 5.6 Cu, .05 Se and 1.0 Mo. The basal lamb diet contained, in mg/kg, 6.1 Cu, .07 Se and less than 1.0 Mo. Sulfur concentrations in the ewe and lamb diets were .24% and .20%, respectively. Copper supplements increased, and Mo supplements decreased, the concentration of Cu in the livers of ewes and lambs (P less than .05). Despite this, there were no effects of treatment on Se concentration or glutathione peroxidase activity in blood or tissues. Selenium levels in plasma of all ewes declined throughout pregnancy and lactation, indicating that .05 mg/kg Se was insufficient for the maintenance of Se status during pregnancy in Hampshire ewes. Copper and Se levels (mg/kg fresh weight) in the liver of lambs at weaning for Treatments 1 through 4 were 48 and .13, 158 and .10, 11 and .11, and 136 and .13, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)