Rodríguez Gutiérrez, Victoria Eugenia, Research Group in Poultry Science, Faculty of Veterinary Medicine, University of Tolima A.A. 546, Altos de Santa Helena, Ibague Tolima. Immunobiology and Pathogenesis Research Group, Faculty of Veterinary Medicine, University of Tolima A.A. 546, Altos de Santa Helena, Ibague, Tolima, Colombia