Comparison of the copper and molybdenum status of yearling steers grazing reclaimed mined-land and native range

Abstract

Spoil material replaced after strip mining for lignite coal may differ from the original top soil with respect to concentrations of copper (Cu) and molybdenum (Mo), consequently levels of these elements may be affected in plants grown on this soil. The objective of the study was to compare the Cu and Mo status of yearling steers grazing mined-land and native range forage to determine whether mined-land grazed steers were more prone to molybdenosis and/or Cu deficiency. Vegetation samples were collected from both mined-land and native range pastures. Copper was marginal and Mo was slightly high, for beef cattle, in forage obtained from both study sites. Blood serum and liver biopsy samples were taken from yearling steers at the initiation and termination of grazing on reclaimed mined-land and native range in 1978, 1979, 1982, and 1983. For the 4 years, there was no significant difference between forage sources with respect to Cu and Mo levels in the liver or Mo levels in the serum. However, serum Cu was slightly (P<.10) lower in steers grazing on mined-land. Liver Cu levels were marginal in steers grazing on either mined-land or native range. Initial liver Mo levels were slightly above normal but did not increase to levels expected if animals were consuming a diet excessively high in Mo. No symptoms of Cu deficiency or molybdenosis were observed during the course of the study. However, marginal serum, liver and forage Cu levels measured suggest that central North Dakota ranchers should be alert to the possibility of a Cu deficiency, whether cattle are grazing reclaimed mined-land or native range.