Purpose: The aim of this work was to evaluate the presence of veterinary drugs in 132 Brazilian raw milk samples collected from bulk tanks in Minas Gerais state.
Methods: Milk samples submitted to analysis of 30 analytes by liquid chromatography coupled to mass spectrometry in tandem. The antimicrobial groups, analytes, and MRL (Maximum Residue Limit) according to Brazilian legislation (expressed in µg/kg) were: a) Beta-lactam: Penicillin G and V (4.0/each), Ceftiofur (100.0), Cloxacillin, Oxacillin, and Dicloxacillin (30.0/each); b) Tetracyclines: Chlortetracycline, Doxycycline, Tetracycline and Oxytetracycline (maximum value 100.0); c) (Fluor) Quinolones: Oxolinic acid, Nalidixic acid, Norfloxacin, Sarafloxacin, and Difloxacin (not described); Flumequine (50.0), Ciprofloxacin, and Enrofloxacin (100.0/each); d) Sulfonamides: Sulfadimethoxine, Sulfaquinoxaline, Sulfadiazine, Sulfathiazole, Sulfapyridine, Sulfamethoxazole, Sulfamethazine, Sulfachlorpiridazine, Sulfizoxazole, Sulfadoxine, and Sulfamerazine (maximum value 100.0) and Trimethoprim (not described).
Results: Residues of Penicilin V (0.76%), Ceftiofur (5.30%), Oxacillin (1.52%), Dicloxacillin (1.52%), Oxytetracycline (2.27%), Ciprofloxacin (2.27%), and Enrofloxacin (2.27%) were detected. Only Penicillin V was detected in concentrations above the MRL (almost two folds) in all positive milk samples with the value of 7.95 µg/kg. The presence of these drugs in milk may be associated with treatments of infectious diseases in dairy cattle, mainly mastitis.
Significance: Although residues of antimicrobials have been detected in raw milk, the frequency of samples with values above the MRL was low, indicating that the these drugs have not been used in an abusive manner. The monitoring of these residues is important and must be done systematically to keep the food safety and protect the consumers.