ANTIMICROBIAL RESIDUES IN POULTRY LITTER: a study of its occurrence in farms with different production management and evaluation of a simple waste composting process

LUCAS L. ALONSO; NATALIA S. PODIO; IRMA I. BERNIGAUD; NATALIA S. ALMADA; JUAN M. GANJE; DANIEL A. WUNDERLIN

Congreso; SETAC Europe 33rd Annual Meeting; 2023

SETAC Europa

In recent years, poultry litter (PL) has gained value under the circular economy perspective due to its advantages as an agricultural fertilizer. However, the use of antimicrobials (AMB) for poultry growth promotion or preventive use, in addition to therapeutic use, implies an intake of these compounds, which can result in the excretion of up to 90% of the parent compound. The presence of AMB in this material poses a risk, considering their release into terrestrial and aquatic environments, and the potential spread of microbial resistances among the soil microbiome. Given the magnitude of poultry production in Argentina, and in accordance with the One Health perspective, it is relevant to generate baseline information that contributes to the characterization of the potential risks that this practice may entail. Because of this, we analyzed the presence of AMB in PL from farms with different management practices. Besides, a typical composting process applied in situ in the farms (15 days of stacking with a turning at half-time) was conducted on a representative sample to evaluate the dissipation of the AMB after PL treatment. For the analysis, and due to the complexity of the matrix, different extraction methodologies were tested, based on (1) ultrasound and solid-phase extraction or (2) salt-assisted solvent extraction. For the latter type of extractions, 5 variations of solvents and salts were tested. The final method consisted of extraction at pH = 7, with acetonitrile and NaCl. PL samples from 19 farms were analyzed in triplicate by UHPLC-QqQ (Waters). Of the 23 studied AMB, 20 were detected in the different samples at levels ranging from 0.001 mg/kg () to 25.3 mg/kg (Sulfamethoxazole). Fluoroquinolones and tylosin were among the most frequently detected compounds, while ionophores presented the overall highest concentrations. Farms with restricted use of AMB in feed presented less occurrence and load of these compounds in PL. Furthermore, it was observed that the applied self-heating process on a representative sample (with 14 AMB detected), the concentration of nine compounds was reduced by more than 50%. The overall results highlight the relevance of AMB surveillance in the PL residue, taking into account the diversity and load of compounds detected. Finally, restricting the addition of AMB into feed and composting processes may help reduce the load of these compounds in the final residue.