Determination of antimicrobial residues in some biological samples of beef cattle before and after slaughter by biochip array technique

Antimicrobial drugs, which are widely used in veterinary medicine, can cause residues in animal-origin foods if they are used unconsciously. Antibiotic residues in food are a serious public health problem with global implications. Routine residue analysis in livestock are carried out mostly on food value tissues obtained after slaughtering. Detection of antibiotic residues in biological samples taken before slaughter will ensure that the presence of residues is manageable. Thus, an environment of trust might be occurred for food safety, public health and exports. Aim of this study to determined whether the presence of residues could be detected in biological samples such as serum, oral fluid and feces taken before slaughter from beef cattles by biochip array, practically. Beef cattles were treated with therapeutic doses. In addition, aimed to asses whether the antimicrobial drug concentrations detected in the liver, kidney and muscle samples of the animals exceed the maximum residue limits at the end of the withdrawal times. In this way, it will be evaluated the compatibility of the withdrawal periods of antimicrobials with practice. Commercial preparations of 8 different antimicrobial drugs (oxytetracycline, ceftiofur, enrofloxacin, tylosin, tilmicosin, florfenicol, penicillin G and amoxicillin), which are frequently used in veterinary medicine, were applied to totally 32 beef cattle (8 groups of 4 each) in accordaning to prospectus information. Sample collection days were determined by considering the withdrawal times of the applied antimicrobials. Before slaughter serum, oral fluid, and feces; after the slaughtering liver, kidney, and muscle samples were taken and analyzed with the biochip array technique. Some positive samples were confirmed by LC-MS/MS. According to the biochip array results, determined that could be detected of oxytetracycline, enrofloxacin, tylosin, tilmicosin, florfenicol, penicillin G and amoxicillin in serum; oxytetracycline, ceftiofur, enrofloxacin, tylosin and tilmicosin in oral fluid; tylosin and florfenicol in feces samples. At the end of the withdrawal period, it was determined that the antimicrobials detected in the liver, kidney and muscle samples did not exceed the maximum residue limit with the exception of tylosin and the withdrawal periods were compatible. Concentrations of tylosin in two liver and one kidney samples determined by biochip array technique were confirmed by LC-MS/MS and it was determined that the results exceeded the maximum residue limits. Withdrawal time of tylosin specified in the prospectus may be insufficient and should be reviewed with more comprehensive studies. As a result, determined that antimicrobial residues can be detected quickly and practically in the samples taken before and after slaughter by the biochip array based immunoassay method. The biochip array technique used in the study is the screening test, so that it is necessary to confirm the positive results by chromatographic methods in order to evaluate the presence of antimicrobial residues accurately.