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

Investigation of doxycycline residues in bones after oral administration to broiler chickens

Introduction

Chicken bones, a by-product of the poultry industry, can directly or indirectly enter the food chain. Bone meal and bone products could be sources of many contaminants. Considering the wide range of uses made of bones in the culinary and food industries, this material needs to be safe and antibiotic residue-free. To determine if such is the case, the concentration of doxycycline in chicken bones was investigated, this antimicrobial being one of the most commonly used in poultry production.

Material and Methods

Ross 308 broilers were grouped into three experimental and one control group. Doxycycline was administered in drinking water at therapeutic and sub-therapeutic doses, as well as via spray treatment. The concentration of doxycycline in bones was determined post slaughter by ultra-high performance liquid chromatography-tandem mass spectrometry.

Results

Doxycycline was quantified at 135 μg/kg 22 days after the last day of antibiotic administration at therapeutic doses; 2,285 μg/kg after sub-therapeutic treatment for 27 days and 9.62 μg/kg 22 days after the end of spray application.

Conclusion

High concentrations and long persistence of doxycycline in bones were found in this study. Doxycycline can contaminate all bone-derived products in the food and fertiliser industries.

Florfenicol and Florfenicol Amine Quantification in Bull Serum and Seminal Plasma by a Single Validated UHPLC-MS/MS Method

Florfenicol is a broad-spectrum antibiotic belonging to the amphenicols class that inhibits protein synthesis by binding to bacteria's ribosomal subunits. This drug is commonly used in veterinary medicine to treat bacterial infectious diseases in cattle, swine, poultry, and fish. The proposed method uses a quick protein precipitation with acetonitrile for the extraction of florfenicol and florfenicol amine in serum and seminal plasma, followed by analysis in UHPLC-MS/MS for their simultaneous quantification. A BEH C18 reversed-phase column was chosen for analyte separation, allowing to obtaining sharp and symmetrical peak shapes in a chromatographic run of just 3.5 min under programmed conditions. Two specific transitions were observed for each analyte, and florfenicol-d3 was used as the internal standard. The approach was fully validated in each matrix over ranges suitable for field concentrations of florfenicol and florfenicol amine, showing good linearity during each day of testing (R² always >0.99). Excellent accuracy and precision were demonstrated, for both analytes, by calculated bias always within ±15% and CV% always below 15% at all QC levels tested. The satisfactory outcomes obtained during recovery, matrix effect, and process efficiency investigations in serum and seminal plasma confirmed the strength of the method for the quantification of target compounds. To our knowledge, this is the first LC-MS/MS-validated approach for the quantification of florfenicol and florfenicol amine in serum and seminal plasma and was successfully applied for the determination of their concentration-time profiles in bulls. This paves the way to understanding the pharmacokinetics of this antibiotic and its active metabolite in bull's seminal plasma, which will enable the design of more appropriate treatment protocols.

Risk to Public Health Regarding Doxycycline Residues in Chicken Claws

Doxycycline residues in claws may pose a potential risk to humans. A study with broiler chickens was performed to find the concentrations of doxycycline in claws after treatment. For the quantification of the antibiotic of interest in claws, an ultrahigh-performance liquid chromatography-tandem mass spectrometry method was developed. Doxycycline was detectable at 3043 μg/kg at sub-therapeutic treatment, 223 μg/kg after therapeutic doses, and 14 μg/kg after spray application on the last day of the experiment (day 22). Almost 70 days is required for the concentration of doxycycline to reach zero. The obtained results show that monitoring of doxycycline in claws should be implemented.

Assessment of Three Antimicrobial Residue Concentrations in Broiler Chicken Droppings as a Potential Risk Factor for Public Health and Environment

Tetracyclines, sulfonamides and amphenicols are broad spectrum antimicrobial drugs that are widely used in poultry farming. However, a high proportion of these drugs can be excreted at high concentrations in droppings, even after the end of a therapy course. This work intended to assess and compare concentrations of florfenicol (FF), florfenicol amine (FFa), chlortetracycline (CTC), 4-epi-chlortetracycline (4-epi-CTC), and sulfachloropyridazine (SCP) in broiler chicken droppings. To this end, 70 chickens were housed under controlled environmental conditions, and assigned to experimental groups that were treated with therapeutic doses of either 10% FF, 20% CTC, or 10% SCP. Consequently, we implemented and designed an in-house validation for three analytical methodologies, which allowed us to quantify the concentrations of these three antimicrobial drugs using liquid chromatography coupled to mass spectrometry (LC-MS/MS). Our results showed that FF and FFa concentrations were detected in chicken droppings up to day 10 after ceasing treatment, while CTC and 4-epi-CTC were detected up to day 25. As for SCP residues, these were detected up to day 21. Noticeably, CTC showed the longest excretion period, as well as the highest concentrations detected after the end of its administration using therapeutic doses.