Antibiotic residues distribute uniformly in broiler chicken breast muscle tissue.

Use of antibiotics by the poultry industry has the potential to produce residues in edible tissues. In order to protect consumers, the U.S. federal government performs extensive evaluations to quantify residues in edible tissues to ensure that concentrations do not exceed the tolerance level. However, in the case of muscle tissue, the regulatory process does not differentiate between different edible muscle types in poultry. Previous studies performed by our laboratory determined higher fluoroquinolone residue concentrations in breast versus thigh muscle. Thus, if thigh tissues were used for residue monitoring, it would not accurately depict the higher concentrations. It is also possible that residue concentrations vary within tissues. To evaluate this possibility, fluoroquinolone antibiotic residues were determined for different breast sections. One hundred sixty chickens were randomly divided into four groups and dosed at 33 days of age with the fluoroquinolone antibiotic, enrofloxacin (Baytril), at either 25 ppm for 3 days, 25 ppm for 7 days, 50 ppm for 3 days, or 50 ppm for 7 days. Breast fillets were collected from each bird (n = 5 birds per day per group) during the dosing and withdrawal period. Each breast was divided into four sections (upper left, upper right, lower left, and lower right) that were analyzed as individual samples for determination of fluoroquinolone concentration. Our results indicated no significant difference (P > 0.05) in the levels of enrofloxacin residues between breast sections during the dosing or withdrawal periods. Consequently, samples can be collected from any breast section to evaluate fluoroquinolone residue concentrations during the regulatory monitoring process.