Identification of Eimeria species and evaluation of intestinal lesion scores in vaccinated chickens and chickens treated with anticoccidial drugs in the free-range chicken systems

Abstract

The purpose of this research was to identify the Eimeria species, in free-range chickens as well as to propose a prophylactic treatment through vaccination and the use of anticoccidial drugs, and to evaluate the intestinal damages caused by strains of vaccinal and field oocysts. In this system the occurrence of Eimeria species in chickens which were treated and vaccinated were respectively of 46% and 49% for Eimeria maxima, 35% and 28% for Eimeria tenella, 26% for Eimeria acervulina for vaccinated chickens and for those which were treated 8% for Eimeria necatrix and E. praecox. The averages of intestinal damages measured by lesion score were 0.28 and 0.80 respectively in the upper intestine for vaccinated and treated chickens, 0.07 and 0.03 for the middle intestine, and 0.05 and 0.10 for the ceca. The vaccinated chickens showed peaks of oocyst elimination in the 21th day with an average of 70,828 oocysts per gram of excretes and the chickens treated with anticoccidial drugs had an average of 7,020 in the 37th day. Although the vaccinated chickens presented an average of oocysts elimination higher than the treated chickens, the lesion score of these chickens was lower.