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

Abstract

Introduction: Chicken bones, a by-product of the poultry industry, can directly or indirectly enter the food chain. Bone mealand bone products could be sources of many contaminants. Considering the wide range of uses made of bones in the culinary andfood industries, this material needs to be safe and antibiotic residue–free. To determine if such is the case, the concentration ofdoxycycline 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 wasadministered in drinking water at therapeutic and sub-therapeutic doses, as well as via spray treatment. The concentration ofdoxycycline 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.