biostudies-literatureGuan SNational Natural Science Foundation of China ProgramHebei Agriculture Research System1612https://www.ebi.ac.uk/biostudies/studies/S-EPMC12649896biostudies-literatureUnknown14(11)Probiotics are widely used as feed additives in livestock production, yet the overall safety of commercially available veterinary probiotics remains insufficiently assessed. In this study, 33 probiotic products marketed in Northern China were systematically evaluated with respect to strain composition, label accuracy, antimicrobial resistance, and the diversity of resistance genes. A total of 32 <i>Bacillus</i> spp. were isolated, many of which showed resistance to multiple antibiotics. Labeling inaccuracies were prevalent: none of the products specified strain names and numbers, 33% (11/33) failed to report viable bacterial counts, 9% (3/33) lacked their claimed key ingredients, and 21% (7/33) contained isolated strains that did not match the label. High-throughput quantitative PCR (HT-qPBiologyAssessment of Antibiotic Resistance and Microbial Contamination in Commercial Veterinary Probiotic Products.PMC12649896Grant No. 32473072HBCT2024240207HBCT2024250206Wang MZhang TZhang ZWang CGuan SZhao XfalseAssessment of Antibiotic Resistance and Microbial Contamination in Commercial Veterinary Probiotic Products.Probiotics are widely used as feed additives in livestock production, yet the overall safety of commercially available veterinary probiotics remains insufficiently assessed. In this study, 33 probiotic products marketed in Northern China were systematically evaluated with respect to strain composition, label accuracy, antimicrobial resistance, and the diversity of resistance genes. A total of 32 <i>Bacillus</i> spp. were isolated, many of which showed resistance to multiple antibiotics. Labeling inaccuracies were prevalent: none of the products specified strain names and numbers, 33% (11/33) failed to report viable bacterial counts, 9% (3/33) lacked their claimed key ingredients, and 21% (7/33) contained isolated strains that did not match the label. High-throughput quantitative PCR (HT-qP2025-01-01T00:00:00Z2025 Nov2026-05-19T03:21:34.194Z2026-05-19T03:12:18.651ZS-EPMC126498964130040110.3390/biology14111612