A multi-element supplement for grazing sheep. II. Accumulation of trace elements in sheep fed different levels of supplement

Abstract

Sheep were fed an oaten hayllupin mixture (88: 12 W/W) containing either 0, 1.7, 3.3, 6.3, 12 or 21% of a multi-element mineral mix for 6 months. Each sheep was fed sufficient ration to provide 800 g DM of the oaten hay/lupin mixture per day. The accumulation of essential and of potentially toxic elements in the tissues of the sheep was measured together with feed intake and growth. Some sheep which were offered 12% and all of the sheep which were offered 21% minerals in the diet refused to eat part or all of the ration and were removed from the experiment. All sheep in the other groups and two sheep which were fed 12% minerals ate all or most of the ration for 6 months. All sheep in the groups which were fed 0, 1.7, 3.3 and 6.3% (equivalent to 0, 15, 30 and 60 g/day of minerals) grew at 27-35 g/day and had similar dry matter intakes after intake of minerals was excluded from the calculation. The two sheep which were fed 12% mineral throughout (equivalent to 120 g/day) lost 6 g/day during the experiment. Intake of minerals increased selenium concentrations in whole blood and liver, and vitamin B12 in plasma. Selenium did not accumulate to levels that resulted in toxicity to the sheep nor exceed maximum permitted levels for human consumption. Fluorine in rib bone increased as mineral intake increased, and sheep which were fed 12% minerals in the diet were at risk of chronic fluorosis. The intake of mineral mix had no significant effect on the concentrations of copper and iron in the liver or the concentration of cadmium in the kidney.