Antibiotic Residues\nin Cattle Reported to Be Raised\nWithout Antibiotics

In\n2019, the U.S. Department of Agriculture’s (USDA) Food\nSafety and Inspection Service (FSIS) provided revised guidance for\nlabeling claims of “raised without antibiotics” (RWA)\nand similar terms for meat and poultry produced in the US. In 2022,\nPrice et al. published a study reporting that 15% of RWA-labeled cattle\ncontained antibiotic residues in urine samples. In 2023, the USDA\nembarked on the project reported herein to independently determine\nthe extent of antibiotic drug residues present in kidney and liver\ntissues from slaughtered cattle purported to be RWA. In this study,\nFSIS inspectors randomly collected kidney and liver tissues from 189\nRWA animals in 79 slaughter establishments across the US. The samples\nwere monitored for 185 veterinary drugs multiple times by different\nmeans, including liquid-chromatography coupled with tandem mass spectrometry\n(LC-MS/MS) and quadrupole high-resolution MS with an orbital ion trap\ninstrument (LC-Q/orbitrap). Samples from 37 animals (20%) met the\nanalytical identification criteria for at least one antibiotic confirmed\nin at least two analyses. Multiple antibiotics were determined in\n11 RWA animals. Macrolides (tulathromycin, tildipirosin, tilmicosin,\nand gamithromycin) were confirmed in 20 (11%) of the RWA animals.\nThe ionophore, monensin, was also confirmed in tissues from 11 samples,\nwith unconfirmed/partial identifications in 8 others. Tetracyclines\nwere confirmed in samples from 12 animals, several of which were found\nto contain multiple antibiotic residues. One animal each was also\nfound to be positive for sulfamethazine (a sulfonamide antibiotic)\nand metabolites of penicillin G (a β-lactam antibiotic). Although\nthey are not antibiotics, two anthelmintics (fenbendazole and eprinomectin)\nwere confirmed in tissues from 3 RWA animals. FSIS has informed the\nslaughter establishments with positive results and advised them to\nconduct a root cause analysis and implement corrective actions.