Comparison of Food Safety Hazards in Pigs and Broilers from Intensive and Extensive Production Systems: A Literature Review

•Food safety hazards in livestock from various production systems were compared.•Pigs and broilers from extensive production had higher T. gondii prevalence.•Pathogens prevalence in pigs did not seem to be affected by production systems.•The prevalence of antimicrobial resistance was higher in intensive production.•Limited data on chemical hazards showed generally low contaminant levels. Consumer demand for meat from extensive production (e.g., organic, free-range, and antimicrobial-free) is increasing, partly due to consumers’ perception that these types are safer than conventional meats. This review compared food safety hazards (namely, zoonotic parasites, bacterial pathogens, antimicrobial resistance, and chemical hazards) from pigs and broilers raised in intensive and extensive systems in Northern and Western European countries and the United States. Our findings showed that hazard occurrence between livestock production systems varied depending on the hazard. Pigs and broilers from extensive systems showed a higher prevalence of Toxoplasma gondii. Pathogen prevalence in pigs did not appear to be affected by production systems, while no clear conclusion could be drawn for broilers due to conflicting findings. Higher antimicrobial resistance (AMR) prevalence was common in pig and broiler samples from intensive farming, although samples from extensive farming were not free of AMR either. Studies on chemical hazards were limited, showing generally low contaminant levels in both production systems, including persistent organic pollutants, heavy metals, mycotoxins, pesticide residues, and antimicrobial residues. Therefore, more studies on chemical hazards are recommended to fill this data gap. Various factors associated with specific production systems could influence hazard prevalence, e.g., indoor confinement, outdoor access, antimicrobial policy, and slaughtering age. Regardless of the production system, other factors, such as seasonal variation and biosecurity levels, were also important.