Changing dietary S intakes and the Cu status of grazing lambs

Abstract

The effect of increasing intake of sulphur (S) as elemental‐ and thiosulphate sulphur on copper (Cu) concentrations in digesta, plasma, and liver tissue was studied in 42 lambs grazing a ryegrass/white clover pasture containing 2.6 g S, 6.2 mg Cu, and <0.5 mg Mo per kg DM. Increasing S intakes from 3.9 to 7.9 g S/day via dosing with thrice weekly S containing capsules had no effect on plasma and liver Cu concentrations at Cu intakes of 9.3 or 24.3 mg/day but significantly (P < 0.05) increased red blood cell superoxide dismutase activity, the total S, acid volatile, and free S2’ concentrations in the reticulorumen contents. It was concluded that increasing S intakes from 3.9 to 7.9 g/day had no significant effect on the Cu status of sheep grazing low Mo pasture (<0.5 mg Mo/kg DM).