The efficacy of a poultry commercial anticoccidial vaccine in experimental challenge with Eimeria field isolates

BACKGROUND: The control of coccidiosis in poultry industryis dominated by prophylactic chemotherapy; however,drug resistance is a serious problem. Alternative control methodssuch as vaccination have been accepted as a practical method forcontrolling coccidiosis in chickens. Considering the immunologicalvariation of Eimeria strains, the efficacy of live coccidiosisvaccines may be compromised. OBJECTIVES:To evaluatethe efficacy of a commercial anticoccidial vaccine in poultry,vaccination was followed by experimental challenge with 3Eimeria field isolates. METHODS: The efficacy of Livacox® Qanticoccidial vaccine was evaluated on male broiler chicks,reared in battery cages. Different factors including weight gain,FCR, OPG (oocysts per gram of feces) and intestinal lesionscores were assessed. RESULTS: Vaccinated challenged groups(VC) gained less weight than the un-vaccinated un-challenged(UVUC) birds (p£0.05). Fourteen days post-challenge, theweight gain of VC groups challenged with isolate 2 differedsignificantly from its un-vaccinated challenged (UVC)counterpart; however, there were no significant differences inweight gain of groups challenged by isolates 1 and 3 with theirrespective UVC groups. Lesion score and FCR weresignificantly improved in VC groups comparing with theirassociated UVC groups (p£0.05). Lesion score and FCR weresignificantly improved in VC groups comparing with their UVCcounterparts (p|£|0.05). CONCLUSIONS: The present studysuggests that the use of live anticoccidial vaccine has thepotential for improving live weight gains and FCR; nonetheless,immunity to local Eimeria species should be evaluatedseparately and in trial designs it should be more approximate tothe actual field condition.