Influence of Breed and Dietary Cu, Mo and S Levels on Biliary Cu Excretion in Cattle
Bile is considered to be the major route of copper (Cu) excretion. But studies on dietary components which interact with Cu to produce Cu deficiency have rarely focussed attention on this route of Cu excretion. Thiomolybdates (TM) formed in the rumen are primarily responsible for the induction of Cu deficiency in ruminants fed high levels of molybdenum (Mo) and sulfur (S). We (Gooneratne et al, 1985) have shown that intravenous (iv) administration of TM increases biliary Cu excretion and lowers liver Cu level in sheep. But bile Cu excretion in cattle, following TM administration or fed excess Mo and S to induce synthesis of TM in the rumen, is not known. Breed related Cu deficiency in sheep is well recognized. In Saskatchewan Cu deficiency may be observed more frequently in Simmental than in other breeds. In rats biliary Cu excretion is strain dependent (Nederbragt and Lagerwerf 1986). The present investigation was carried out to determine biliary Cu excretion in 2 breeds of cattle Simmental and Angus, in response to changes in Cu (low (L) = 5 or high (H) = 40 mg/kg), and/or Mo (L = 1 or H = 10 mg/kg) and/or S (L = 0.2% or H = 0.5%) in the diet. Bile Cu excretion was also monitored following iv administration of TM.
KeywordsZinc Manganese Molybdenum
- Gooneratne, S.R., Christensen, D., Chaplin, R., and Trent, A. (1985) Copper: Biliary excretion in copper-supplemented and thiomolybdate treated sheep. In Proc. of 5th Int. Symp. on trace elements in man and animals. p. 342–345 C.F. Mills, I. Bremner, and J.K. Chesters, eds., Commonwealth Agricultural Bureau, UK.Google Scholar