Underestimated Cumulative Intake Risk of Veterinary Antibiotics Across Multiple Matrices within a Coupled Breeding–Cropping Model

The coupled breeding-cropping model has been increasingly applied in organic agriculture due to its high resource efficiency; however, the environmental risks of veterinary antibiotics within the solid–liquid-biological system remain unclear. This study focused on a typical poultry-crop system and investigated the migration patterns of enrofloxacin (ENX), ciprofloxacin (CIP), oxytetracycline (OTC), doxycycline (DOX), and florfenicol (FF) in manure, drain, paddy soil, and agricultural products. A strong source-sink relationship was established, with paddy soil identified as the primary reservoir, retaining over 40.1% of the total emissions. The migration behavior of antibiotics in the soil-rice system was primarily influenced by their organic carbon-normalized distribution coefficients, ionization forms, and soil organic carbon contents. Importantly, the cumulative risk of the five antibiotics was 1.4–828 times higher, exceeding risk thresholds by 13.9-fold. These findings emphasize the underestimated cumulative risks of mixed antibiotic use in agroecosystems.