DETECTION OF TETRACYCLINE RESIDUES IN BOVINE MILK FOLLOWING MASTITIS TREATMENT

The purpose of this study was to check tetracycline residues in milk from treated mastitic quarters. Milk from 35 cows, which were intramammary treated with a preparation containing tetracycline, was collected before and after the withholding period. Twinsenor, a competitive receptor-based test was used for quick detection of tetracycline residues. The positive samples were analyzed with LC-MS/ MS. In none of the untreated quarters tetracycline residues were detected. In 40% of the milk from treated quarters tetracycline residues were above Maximum Residue Limit after the withdrawal period. In 11.4% the concentration of tetracycline was above the 700 mu g/ kg. The withholding period stated in the label of the medicinal product is determined in healthy animals and only for that particular medicinal product. During mastitis the conditions in the quarter are different, the production of milk usually decreases, and thus the excretion time can differ compared with a healthy animal. From the treatment records, we could see that sometimes the treatment was extended, always more than one antimicrobial product were used, and the withholding time was prolonged.