Determination of mineral balances in sheep offered feed with added cadmium and zinc

The optimum conditions for microwave digestion of herbage and faeces to determine mineral concentrations were obtained by varying sample mass, reagent and heating programme, and it was confirmed that the resulting element concentrations were the same as for certified reference material. The effects of feeding cadmium to sheep at a level that is typical of polluted regions (1 mg/kg) for ten days were investigated, as well as the possible amelioration of cadmium effects by adding 30 mg/kg Zn to the diet. Cadmium in the feed increased the cadmium balance and produced several mineral disturbances, in particular a reduction in sodium balance which is typical of renal tubular disorders. Including zinc in the diet as well as cadmium reduced the cadmium balance to a level similar to that of sheep that did not receive cadmium or zinc, which suggests that the zinc status is critical in determining whether cadmium in feed increases the cadmium balance in sheep. Received: 1 August 1997 / Revised: 8 December 1997 / Accepted: 10 December 1997