Effects of virginiamycin against experimentally induced necrotic enteritis in broiler chickens vaccinated or not with an attenuated coccidial vaccine

Abstract

SUMMARY Necrotic enteritis (NE) is a deadly poultry disease caused by Clostridium perfringens. Infeed antibiotics such as virginiamycin (Vm) are commonly used in many countries to control NE. A ban on in-feed antibiotics usage in some European Union countries has caused an increase in the incidence of NE. In the present investigation, first, the effects of a live attenuated coccidial vaccine on the severity of experimentally induced NE in broilers and the role of Vm in prevention of disease were assessed. Second, we studied whether Vm, salinomycin (Sm), or both would help to reduce the severity of NE. The results of the first study showed that although the administration of a double dose of an attenuated coccidial vaccine led to a higher morbidity and mortality among C. perfringens-challenged birds, Vm prevented mortalities and improved the performance parameters among the vaccinated birds. In the second study, administration of Vm and Sm for 30 d were efficacious in preventing NE induced by C. perfringens which had been previously isolated from acute cases of NE in broiler farms. However, the short-term effects of in-feed Vm against NE, although evident in reducing the mortalities, were not satisfactory. This study provides further evidence that in-feed Vm benefits the poultry industry by prevention of NE.