RESUMEN
The aim of this study was to evaluate the antimicrobial activity of essential oils on enterobacteria Escherichia coli and Staphylococcus aureus isolated from poultry fecal samples in the cloaca from 49 laying hens. To analyze the antimicrobial sensibility an agar diffusion susceptibility test was performed and the Minimum Inhibitory Concentration (MIC) and the Minimum Bactericida Concentration (MBC) of Lippia origanoides and Lippia rotundifolia essential oils was determined. The concentrations used were 160, 80 and 40 L/mL. The L. origanoides essential oil showed antimicrobial effect from 40 L/mL dose against both microorganisms, with larger efficiency in E. coli. The L.rotundifolia essential oil was more efficient at the concentration of 160L/mL. Its effect was observed in all microorganisms. These results suggest that L. origanoides oil is more effective than L. rotundifolia oil in inhibiting the growth of microorganism isolated from poultry, although it also has a satisfactory antimicrobial effect. Results indicate the potential use of these plant's essential oils in poultry feed as an alternative to conventional antimicrobial products.