Evaluation of the Effect of Doxycycline Administration on Growth Performance and Tissue Residue Accumulation Kinetics in Hubbard Broiler Chickens

Antibiotic administration in poultry production remains an important One Health concern, particularly because inappropriate use may contribute to antimicrobial resistance and the persistence of antimicrobial residues in food products. This study aimed to evaluate the association between oral doxycycline administration and growth performance in Hubbard broiler chickens, as well as to assess the kinetics of residual antimicrobial activity in selected tissues.

A total of 200 one-day-old Hubbard broiler chicks were divided into two groups of 100 birds each: a control group receiving a standard diet without doxycycline treatment and a treated group receiving doxycycline at 20 mg/kg body weight through drinking water from day 22 to day 42 of rearing. Growth performance was assessed by monitoring body weight, feed intake, and average daily gain. In parallel, tissue samples, including liver, kidneys, muscle, and adipose tissue, were collected to evaluate residue accumulation using a microbiological inhibition assay based on the detection of residual antimicrobial activity.

The doxycycline-treated group showed higher body weight and greater weight gain compared with the control group. Statistical analysis confirmed a significant association between doxycycline administration and improved growth-related parameters (p < 0.001). Residual antimicrobial activity was detected in all analysed tissues, with greater accumulation observed in the liver and kidneys.

These findings indicate that, under the conditions of this study, doxycycline administration was associated with improved growth performance in Hubbard broiler chickens. However, the persistence of residual antimicrobial activity in edible tissues raises important food safety concerns. Therefore, doxycycline use in poultry production should be strictly controlled to ensure food safety and compliance with One Health principles.