LAUSR

Dairy farm waste, commonly used as agricultural fertilizer, often contains veterinary drugs and their metabolites, posing a potential risk to human and animal health, particularly by promoting antimicrobial resistance. This study investigated the occurrence of 11 veterinary pharmaceuticals in effluents, solid manure, and slurry from 53 dairy farms in a key dairy region of Central Argentina. Samples of cow manure and wastewater effluent were collected and analyzed using LC‐MS/MS after liquid‐liquid extraction. The analyzed drugs were detected in 68% of effluent samples and 38% of manure samples. Oxytetracycline was the most frequent compound in both matrices (effluents and manure) (26.4% and 47.2%), with concentrations of 12 µg/L and 86 µg/kg, respectively. Flunixin, a nonsteroidal anti‐inflammatory, was present in 84.9% of liquid effluent samples (0.01–11 µg/L) and 18.9% of manure samples (1.3–124 µg/kg). Associations were found between pharmaceutical residues in waste and farm characteristics. Higher concentrations and detection rates of oxytetracycline and flunixin in manure were observed in confined production systems, farms with high milk productivity (>25 L/cow/day), and larger herd sizes (≥182 animals). The relative risk of detecting tylosin in effluents was higher in these same farm categories (RR = 7.8, confined systems; 7.3, high milk productivity; and 6.2, larger herd). Similar trends were noted for enrofloxacin, tetracycline, and flunixin in manure. Despite generally low concentrations (in the order of ng/L or kg), this work demonstrates the widespread occurrence of veterinary drugs in dairy farm waste, often overlooked in fertilizer application. This highlights the need for incorporating veterinary drug monitoring for a fair assessment of environmental impacts as dairy production intensifies.