The effect of molybdenum, iron and sulphur supplementation on growth rate and copper status of lambs

Abstract

For sheep and cattle, primary copper deficiency may occur due to a lack of copper within the feed or soil, whereas secondary copper deficiency may occur in the presence of a combination of high dietary levels of molybdenum (Mo), sulphur (S) and/or iron (Fe). This is due to the anaerobic interactions within the rumen (Phillippo et al., 1987) resulting in thiomolybdate production. Recent work suggests that iron may play a significant role in copper absorption. Mackenzie et al. (1997) proposed that a caeruloplasmin to plasma copper ratio may provide a more accurate biochemical indicator of copper status than other current techniques of assessment. A low ratio may suggest that thiomolybdate is being absorbed into the blood which reduces activity of the copper enzymes. The objective of this experiment was to assess the effect of molybdenum and iron in the presence of sulphur on the copper status and performance of intensively reared lambs, and to predict the accuracy of this ratio when assessing the effects of molybdenum or iron on copper metabolism.