Residues of enrofloxacin and its main metabolite ciprofloxacin in broiler chickens

Abstract

The presence of enrofloxacin residues in muscle and liver after peroral administration of enrofloxacin (10 mg/kg bw/day) to chickens was studied. Microbiological method - plate pH 8.0 with Escherichia coli NCIMB 11595 and HPLC with fluorescence detection were used for the detection of enrofloxacin residues. During the 5 days dosing period, enrofloxacin concentrations in breast muscle and liver greatly exceeded the EU MRL values. Ciprofloxacin was not detected in muscles after 2 days of dosing, but it was detected in the liver in concentrations over the MRL. During the post treatment period enrofloxacin and ciprofloxacin concentrations in the breast muscle and liver exceeded the MRL values until the 4th day of the withdrawal period. Ciprofloxacin was not detected in the breast muscle after 4 days post dosing, but it was detected in the liver at concentrations below MRL. Four days withdrawal period is the allowed time for the drug concentration to decrease to an acceptable level in the meat and liver, prior to slaughter (below MRL). Microbiological method - plate pH 8.0 with Escherichia coli NCIMB 11595 gave positive results in all the samples which had residues above MRL values.