Abstract
<strong>Objective:</strong> To evaluate blood parameters in broiler chickens of the Cobb 500 genetic line, after the administration of oregano essential oil (<em>Lippia origanoides</em>) (OEO). <strong>Materials and methods:</strong> 200 chickens of the Cobb 500 genetic line were used, and measurements were taken on days 14, 28, and 42. The animals were randomly assigned to one of two diets: commercial diet with and without antibiotic supplementation. To the antibiotic-free diet different concentrations of OEO were added (75 ppm, 100 ppm, or 200 ppm). A statistical randomized block design was used in an array of divided plots. <strong>Results:</strong> Chickens from group D5 (200 ppm of OEO) had higher values in glucose, phosphatase, and phosphorus than chickens fed with antibiotic supplementation (D2) throughout the experiment. <strong>Conclusion:</strong> The addition of 200 ppm of OEO in the food of broiler chickens of the Cobb 500 genetic line induces an improvement in blood metabolites. This work allowed evaluating metabolic variables of chickens that consumed OEO