title: Detection of melengestrol acetate residues in plasma and edible tissues of heifers.
abstract: The aim of this study was to gain knowledge of residue formation after the use of melengestrol acetate (MGA) as a growth-promoting agent. Two Holstein-Friesian heifers each received a daily dose through the feed of 0, 0.5 mg (2 heifers with and without withdrawal each), 1.5 mg or 5.0 mg MGA for 8 weeks. MGA residues in plasma were screened by enzyme immuno-assay (EIA). Concentrations in kidney, liver, and muscle were quantified by liquid-chromatography-mass spectrometry (LC-MS), and in fat by gas chromatography-mass spectrometry (GC-MS). MGA levels in plasma were 40, 128, and 280 ng/L, respectively. Residues accumulated in muscle and kidney (5-fold), liver (20-to-40-fold), and fat (200-fold). After administration of 1.5 mg per day the mean MGA concentration in fat was 29 micrograms/kg and thus violated USA regulations which specify a limit of 25 ppb. Therefore the labelled use of MGA (0.5 mg per day) has to be officially controlled.
authors.affiliation: Institut für Physiologie, Forschungszentrum für Milch und Lebensmittel, TU München-Weihenstephan, Germany. daxenbg@weihenstephan.de
authors.forename: A
authors.initials: A
authors.lastname: Daxenberger
authors.forename: K
authors.initials: K
authors.lastname: Meyer
authors.forename: M
authors.initials: M
authors.lastname: Hageleit
authors.forename: H H
authors.initials: HH
authors.lastname: Meyer
mesh_terms: D000273:Adipose Tissue / Q000737:chemistry / Q000378:metabolism; D000818:Animals; D002417:Cattle; D004350:Drug Residues / Q000032:analysis* / Q000493:pharmacokinetics; D005260:Female; D007668:Kidney / Q000737:chemistry / Q000378:metabolism; D007881:Legislation, Food; D008099:Liver / Q000737:chemistry / Q000378:metabolism; D008460:Meat / Q000592:standards*; D008552:Melengestrol Acetate / Q000032:analysis* / Q000097:blood / Q000493:pharmacokinetics*; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism; D014018:Tissue Distribution; D014481:United States
chemical_list: D008552:Melengestrol Acetate