Comparative analysis of antibiotic-administered vs. antibiotic-free farming in meat production: Implications for health, environment, and antibiotic resistance.

Antimicrobial resistance (AMR) is an escalating global health problem, endangering human, animal, and environmental health. In animal farming, the widespread use of antimicrobials is recognized one of the major drivers of AMR. Therefore, this review provides a meta-analysis of 37 studies published between 2014 and 2024, comparing the prevalence of antimicrobial resistance genes (ARGs) in antibiotic-free (ABF) versus conventional animal farming (CONV) systems. The statistical analysis revealed that CONV farms exhibited a higher likelihood of harboring ARGs, with a pooled odds ratio of 2.38 (95 % CI: 2.00-2.83) in the fixed-effects model and 3.21 (95 % CI: 1.68-6.13) in the random-effects model. Significant heterogeneity was observed (I = 82.8 %, p < 0.0001), highlighting the variations across the study designs. However, ARGs were still detected in 97 % of ABF farms, suggesting that antibiotic reduction alone may not be enough to control AMR in animal farming. These findings underscore the complex nature of AMR, influenced by environmental contamination, microbial interactions, human practices, and ecological pressures such as climate change. Future strategies should adopt a holistic One Health approach to effectively mitigate AMR risks across sectors and safeguard public and planetary health.