Withdrawal time of danofloxacin and difloxacin and in vitro binding phenomenon to melanin in black‐boned silky fowl

Abstract

AbstractFluoroquinolones are commonly used in poultry breeding. Few studies have evaluated the causes of serious drug residues in black‐boned silky fowl until enrofloxacin has been banned in black‐boned silky fowl breeding in the Chinese Veterinary Commission of Chinese Veterinary Pharmacopoeia (2020). However, similarly structured fluoroquinolones have not been studied in black‐boned silky fowl. In this study, the elimination of tissue residues of danofloxacin (DAN) and difloxacin (DIF) was studied in four tissues of black‐boned silky fowl. The specific administration methods were 100 mg/L of DIF aqueous solution for free drinking for 5 days and 50 mg/L of DAN aqueous solution for free drinking for 3 days. Based on the experiment, the withdrawal times of 44 days for muscle, 95 days for skin + fat, 3 days for liver, and 44 days for kidney of DAN were acquired, of 43 days for muscle, 61 days for skin + fat, 0 days for liver, and 38 days for kidney of DIF were acquired, which showed that DIF and DAN should be used with caution for application in black‐boned silky fowl. In vitro experiments showed that black‐boned silky fowl tissues had stronger adsorption capacity to DAN and DIF than yellow chicken tissues (especially in skin + fat), and melanin has a strong adsorption effect on DAN and DIF, which is an important reason for the high residual concentrations of fluoroquinolone in black‐boned silky fowl.