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United States Department of Agriculture

Agricultural Research Service

Research Project: METABOLIC FATE OF CHEMICAL AND BIOLOGICAL CONTAMINANTS

Location: Animal Metabolism-Agricultural Chemicals Research

Title: Ractopamine uptake from soil by alfalfa (Medicago sativa) and wheat (Triticum aestivum)

Authors
item SHELVER, WEILIN
item Desutter, Thomas -

Submitted to: American Chemical Society National Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 2014
Publication Date: N/A

Interpretive Summary: Ractopamine, a beta adrenergic agonist, is approved to use as feed additive in swine (Paylean®), cattle (Optaflexx®), and turkey (Topmax®) to improve daily weight gain, increase feed efficiency, and produce leaner meat. Because of this economic advantage, ractopamine is widely used. The transfer of pharmaceuticals from animal waste to soils to plants has been of increasing concern and the subject of many investigations. To test whether ractopamine has the potential to accumulate in plants grown in contaminated soil, a greenhouse study was conducted with alfalfa (Medicago sativa) and wheat (Triticum aestivum) grown in two soils differing in organic matter (1.3 and 2.1%) amended with 0, 0.5, and 10 µg/g of ractopamine. Plant growth ranged from 2.7 to 8.8 g dry weight (dw) for alfalfa, 24 to 31 g dw for wheat and was generally greater in soils of higher organic matter content but the level of ractopamine did not affect plant growth. The uptake of ractopamine in plant tissues ranged from non-detectable to 740 ng/g for alfalfa, from non-detectable to 40 ng/g for wheat straw, and was non-detectable for wheat grain. For alfalfa and wheat straw, the uptake concentration was strongly dependent on ractopamine concentration applied to soil. In general, uptake increased with decreasing organic content. When adjusted to the total fortified quantities, the amount of ractopamine taken up by the plant tissue was low, <0.01 % for the two soil types.

Technical Abstract: Ractopamine, a beta adrenergic agonist, is approved to use as feed additive in swine (Paylean®), cattle (Optaflexx®), and turkey (Topmax®) to improve daily weight gain, increase feed efficiency, and produce leaner meat. Because of this economic advantage, ractopamine is widely used. The transfer of pharmaceuticals from animal waste to soils to plants has been of increasing concern and the subject of many investigations. To test whether ractopamine has the potential to accumulate in plants grown in contaminated soil, a greenhouse study was conducted with alfalfa (Medicago sativa) and wheat (Triticum aestivum) grown in two soils differing in organic matter (1.3 and 2.1%) amended with 0, 0.5, and 10 µg/g of ractopamine. Plant growth ranged from 2.7 to 8.8 g dry weight (dw) for alfalfa, 24 to 31 g dw for wheat and was generally greater in soils of higher organic matter content but the level of ractopamine did not affect plant growth. The uptake of ractopamine in plant tissues ranged from non-detectable to 740 ng/g for alfalfa, from non-detectable to 40 ng/g for wheat straw, and was non-detectable for wheat grain. For alfalfa and wheat straw, the uptake concentration was strongly dependent on ractopamine concentration applied to soil. In general, uptake increased with decreasing organic content. When adjusted to the total fortified quantities, the amount of ractopamine taken up by the plant tissue was low, <0.01 % for the two soil types.

Last Modified: 8/27/2014
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