Effect of Tall Fescue and Quackgrass on Copper Metabolism and Weight Gains of Beef Cattle

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Abstract
Rapid copper depletion without clinical signs of copper deficiency was found in yearling beef heifers under natural Klamath Basin (Oregon) conditions. Copper metabolism in the animals was influenced by grass species grown as feed in the muck soils of this area. Consumption of tall fescue, Festuca arundinacea Schreb., reduced liver copper stores (P < .02) and decreased plasma copper (P < .001) and ceruloplasmin oxidase activity (P < .001) to a deficiency level in less than 4 months. At the same time cattle fed quackgrass, Agropyron repens (L.) Beauv., maintained normal blood copper and ceruloplasmin activity levels and increased liver copper stores. Quackgrass was lower than fescue in copper content (4.6 ppm and 6.6 ppm, respectively), molybdenum (1.2 ppm and 2.3 ppm, respectively), sulfur (.16% and .34%, respectively) and manganese (38 ppm and 91 ppm, respectively). Tall fescue produced lower (P < .001) daily weight gains (.55 kg) than quackgrass (.71 kg). Daily gains were not improved by copper supplementation. Grass species and/or copper supplementation did not affect whole blood zinc and liver iron, molybdenum and zinc concentrations. Copyright © 1979. American Society of Animal Science . Copyright 1979 by American Society of Animal Science.