An essential nutrient in a pigs diet is zinc, with minimum levels need around 100 ppm. In early starter rations, zinc oxide is often used therapeutically to control post-weaning E. coli diarrhea in levels of 2000 to 3000 ppm. Zinc oxide used therapeutically may create selective pressure from methicillin-resistant Staphylococcus aureus (MRSA) due to co-localization of the methicillin-resistance gene and the zinc-resistant gene in the cassette chromosome mec. High levels of zinc oxide fed to piglets may increase the incidence of antibiotic resistant pathogens. MRSA was much higher when fed a zinc oxide ration of 3000 ppm compared to the control group of 100 ppm. Higher prevalence of MRSA is found when starter rations have high levels of zinc oxide.
Zinc Oxide and Antimicrobial Resistance in Pigs (full article)
