Effects of vaccination against coccidiosis, with and without a specific herbal essential oil blend, on performance, oocyst excretion and serum IBD titers of broilers reared on litter

The aim of the present experiment was to investigate the effects of oral administration of a live attenuated vaccine (VAC) and an essential oil blend (EOB), either alone or in combination, as a novel anticoccidial strategy for broiler chickens with a mixed Eimeria spp. infection. A total of 624 broiler chicks were randomly assigned to one of six treatments. Two of the groups, only one of which was challenged with coccidiosis, were given a basal diet and served as controls. The other two groups, also infected, were given a basal diet supplemented with monensin sodium (MON, 100 mg/kg) or the EOB (75 mg/kg). Of the remaining two groups, which were infected with coccidiosis, one was vaccinated against coccidiosis (VAC) and the other was both vaccinated and fed a diet with an EOB (VAC+EOB). Birds treated with VAC and VAC+EOB had comparable live performance to MON-fed birds challenged with coccidiosis. Conversely, EOB diet supplementation had negative effects on growth, feed intake and feed conversion ratio throughout the growth period. None of the coccidial control strategies affected the overall performance of uninfected birds. There was no significant difference in mortality among treatments. All of the anticoccidial procedures kept serum infectious bursal disease titers at high levels after coccidial infection and reduced fecal oocyst excretion, with the exception of the MON-based procedure. The results indicate that vaccination against coccidiosis, with or without EOB, demonstrated the same efficacy in promoting recovery from coccidial infection and in reducing oocyst shedding as MON