Zinc Toxicity in Ruminants. I. Effect of High Levels of Dietary Zinc on Gains, Feed Consumption and Feed Efficiency of Lambs

Effects of dietary molybdenum, sulfur and zinc on the excretion and tissue accumulation of trace elements in sheep fed palm kernel cake-based diets

“…In spite of the reduced body Cu retention and the reduced concentrations of Cu in blood plasma and kidney, the reduced liver Cu concentration due to the Zn supplement was still in the range of the liver Cu overload and marginal toxicity (Underwood and Suttle, 1999). It should be noted that in the present experiment, supplemental Zn resulted in a relatively high dietary Zn concentration, but it was much lower than that (1 g/kg DM) resulting in a lower feed intake and growth of lambs (Ott et al, 1966). The high Zn intake resulted in an unusually high concentration of Zn in blood plasma (4.95 mg/ml) in the present experiment.…”

Effect of zinc and molybdenum supplementation of the feed concentrate on the storage of copper in the liver of lambs

“…Therefore the addition of Zn to concentrates fed to sheep in danger of a Cu intoxication would appear an attractive alternative, as Zn is toxic only at very high levels. Ott et al (14,15) found that Zn at up to 500 ppm in the diet was harmless to sheep and cattle. A reduction in gain and a depressed feed efficiency was seen on addition of Zn at levels in excess of 1000 ppm.…”

Breed differences in sheep with respect to the interaction between zinc and the accumulation of copper in the liver

“…A reduction of the hepatic Cu-level can be obtained only by moderately large amounts of dietary Zn. Under the usual conditions, growing and mature cattle and sheep can tolerate up to 500 ppm Zn in their food without any, and up to 1000 ppm Zn with hardly perceptible, hazardous effects (5,6,7). Although Zn is not regarded as a very toxic element for ruminants, the dietary Znsupplementation during the pregnancy of ewes, particularly when dietary Cu may be marginal, is hazardous.…”