Residue depletion of oxytetracycline (OTC) and 4-epi-oxytetracycline (4-epi-OTC) in broiler chicken’s claws by liquid chromatography-tandem mass spectrometry (LC-MS/MS)

Abstract

Antibiotics are widely used in poultry production for the treatment of bacterial diseases. However, residues may remain in products and by-products destined for human consumption or animal feeding. The claws of chickens, which are a by-product of the poultry industry, can directly or indirectly enter the food chain as meals destined to feed other productive animals. Thus, it becomes necessary to determine and quantify antimicrobial residues present in this matrix. The objective of the study was to assess the depletion of oxytetracycline (OTC) and its metabolite 4-epi-OTC in broiler chicken's claws. Claws of 32 broilers treated with a therapeutic dosage of 10% OTC during 7 days were analysed. Samples were taken at days 3, 9, 15 and 19 post-treatment. As for the control group, eight broiler chickens were raised under the same conditions. Extraction was carried out through EDTA-McIlvaine buffer, and clean-up employed a SPE C-18 Sep-Pak®. Instrumental analysis was performed through LC-MS/MS. The concentrations of both analytes were determined in claw samples until day 19 post-treatment. Average concentrations were within the LOD (20 μg kg) and LOQ (22 µg kg) for OTC and 84 μg kg for 4-epi-OTC. Withdrawal times (WDTs) of 39 days for OTC and 54 days for 4-epi-OTC were established in claws based on 95% confidence. These findings demonstrate that claws can be a source of antimicrobial residue entry into the food chain, since the results showed that OTC and its metabolite can be found in chicken's claws for long periods, even exceeding the average lifespan of a broiler chicken.

Determination of Chlortetracycline Residues, Antimicrobial Activity and Presence of Resistance Genes in Droppings of Experimentally Treated Broiler Chickens

“…This situation was also reported by Cornejo et al [ 42 ], who found that OTC and 4-epi-OTC residues could still be quantified in feathers by day 46 after ceasing treatment. Moreover, withdrawal periods for OTC and 4-epi-OTC in chicken claws have been established at 39 and 54 days, respectively, hence surpassing even the age of slaughter that is currently practiced by the poultry industry [ 44 ]. Such evidence suggests that finding these elevated concentrations of CTC and 4-epi-CTC in chicken droppings on the last sampling day (as well as the observation that concentrations increased on day 21 and 25), could be attributed to the systemic recirculation of these residues from feathers and claws.…”

Evaluation of Oxytetracycline Metabolites Cross-Reactivity with Oxytetracycline Enzyme-Linked Immunosorbent Assay (ELISA)

“…For example, 4-epi-oxytetracycline and N-demethyloxytetracycline were detected as metabolites of oxytetracycline in egg and hen plasma [11]. In another study, 4-epioxytetracycline was also detected in bones (femur, breastbone, fibula, and tibia) from broilers treated with oxytetracycline [12]. In addition, several metabolites were detected as a result of abiotic degradation of oxytetracycline in the soil, including 4-epi-oxytetracycline, α-apo-oxytetracycline, and β-apo-oxytetracycline [13].…”

Residue Depletion of Florfenicol and Florfenicol Amine in Broiler Chicken Claws and a Comparison of Their Concentrations in Edible Tissues Using LC–MS/MS

“…In those studies, they analyzed samples of muscle and bone tissues from broiler chickens who were treated with a therapeutic dose of a 20% oxytetracycline formulation, concluding that their bones evidenced a high bioaccumulation of oxytetracycline in them. Not long after, Cornejo et al [ 10 ] assessed the depletion of oxytetracycline in claws from broiler chickens who received a diet containing a commercial formulation of this drug. These authors found high concentrations of oxytetracycline residues, and these drugs persisted for longer periods than the established withdrawal time for that specific formulation in muscle tissues.…”

“…Meanwhile, studies examining bioaccumulation of veterinary drugs in chicken claws are scarce. One of them [ 10 ] explored the behavior of oxytetracycline (OTC) and its active metabolite (4-epi-oxytetracycline) in broiler chicken claws treated with a therapeutic dose of 10% OTC. By day 3 after ceasing treatment, they quantified concentrations of 2997 µg·kg −1 for both OTC and 4-epi-OTC.…”