Performance of Blue-Yellow Screening Test for Antimicrobial Detection in Ovine Milk

Abstract 

Drug residues in milk are important because of public health and industrial implications. The detection limits of 25 antimicrobial agents were determined by the blue-yellow screening method in ovine milk. For each drug, 8 concentrations were tested on 20 ovine milk samples from individual ewes in midlactation. Detection limits determined by means of logistic regression were below European Union maximum residue limits (EU-MRL) for penicillin G (3 to 4μg/kg), ceftiofur (96 to 107μg/kg), framycetin (720 to 781μg/kg), neomycin (915 to 1,084μg/kg), and tylosin (44 to 51μg/kg). Detection limits for ampicillin (5 to 6μg/kg), cloxacillin (33 to 42μg/kg), cefoperazone (73 to 82μg/kg), cefalexin (160 to 202μg/kg), gentamycin (355 to 382μg/kg), streptomycin (3,063 to 3,593μg/kg), tilmicosin (109 to 131μg/kg), erythromycin (444 to 522μg/kg), spyramicin (1,106 to 1,346μg/kg), sulfadimethoxine (101 to 119μg/kg), sulfathiazole (122 to 151μg/kg), sulfamethazine (309 to 328μg/kg), sulfanilamide (1,750 to 2,674μg/kg), tetracycline (233 to 257μg/kg), oxytetracycline (398 to 501μg/kg), doxycycline (323 to 419μg/kg), chlortetracycline (3,331 to 3,989μg/kg), danofloxacin (4.7 to 5.5 mg/kg), enrofloxacin (41 to 46 mg/kg), and flumequin (63 to 71 mg/kg) were higher than the EU-MRL. Although the blue-yellow method showed improved sensitivity compared with other tests studied in ovine milk, the performance of screening methods for detecting antimicrobial agents in milk of this species should be improved.

Key words: ovine milk, screening test, detection limit, antimicrobial residue