title: Fate of ivermectin residues in ewes' milk and derived products.
abstract: The fate of ivermectin (IVM) residues was studied throughout the processing of daily bulk milk from 30 ewes (taken up to 33 d following subcutaneous administration of 0.2 mg IVM/kg b.w.) in the following milk products: yoghurt made from raw and pasteurized milk; cheese after pressing; 30- and 60-day ripened cheese; and whey, secondary whey and whey proteins obtained after cheese-making (albumin cheese). The concentration of the H2B1a component of IVM was analysed in these dairy products using an HPLC method with fluorescence detection. The mean recovery of the method was, depending on the matrix, between 87 and 100%. Limits of detection in the order of only 0.1 microg H2B1a/kg of product were achieved. Maximum concentrations of IVM were detected mostly at 2 d after drug administration to the ewes. The highest concentration of IVM was found on day 2 in 60-day ripened cheese (96 microg H2B1a/kg cheese). Secondary whey was the matrix with the lowest concentration of IVM (<0.6 microg H2B1a/ kg). Residue levels fell below the limits of detection between day 5 (for secondary whey) and day 25 (for all cheese samples). In the matrices investigated, linear correlations between daily concentrations of IVM, milk fat and solid content were evident. During yoghurt production, fermentation and thermal stability of IVM was observed. During cheese production, approximately 35% of the IVM, present in the raw (bulk) milk samples, was lost. From the results it was concluded that the processing of ewes' milk did not eliminate the drug residues under investigation. The consequences of IVM in the human diet were discussed. Milk from treated animals should be excluded from production of fat products like cheese for longer after treatment with IVM than for lower fat products.
authors.affiliation: Institute of Food Hygiene and Bromatology, Veterinary Faculty of the University of Ljubljana, Gerbiceva 60, SI-1000 Ljubljana, Slovenia. Vesna.Cerkvenik@vf.uni-lj.si
authors.forename: Vesna
authors.initials: V
authors.lastname: Cerkvenik
authors.forename: Bogdan
authors.initials: B
authors.lastname: Perko
authors.forename: Irena
authors.initials: I
authors.lastname: Rogelj
authors.forename: Darinka Z
authors.initials: DZ
authors.lastname: Doganoc
authors.forename: Valentin
authors.initials: V
authors.lastname: Skubic
authors.forename: Wim M J
authors.initials: WM
authors.lastname: Beek
authors.forename: Henk J
authors.initials: HJ
authors.lastname: Keukens
mesh_terms: D000818:Animals; D002611:Cheese / Q000032:analysis; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D003611:Dairy Products / Q000032:analysis*; D004350:Drug Residues / Q000032:analysis*; D005260:Female; D005506:Food Contamination / Q000032:analysis / Q000331:legislation & jurisprudence; D007559:Ivermectin / Q000032:analysis*; D008055:Lipids / Q000032:analysis; D008892:Milk / Q000737:chemistry*; D012756:Sheep; D017524:Slovenia; D015014:Yogurt / Q000032:analysis
chemical_list: D008055:Lipids; D007559:Ivermectin