Improved performance due to dietary supplementation with selected herbal extracts of broiler chickens infected with Eimeria spp.

The aim of the study was to investigate the effect of dietary herbal extracts derived from garlic (Allium sativum), rosemary (Rosmarinus officinalis), sage (Salvia officinalis), oregano (Origanum vulgare), nettle (Urtica dioica), purple coneflower (Echinacea purpurea), or thyme (Thymus vulgaris) on the performance indices and oocyst output in broilers experimentally infected with 190 000 oocysts of Eimeria spp. on day 12 of age. A total of 400 one-day-old Ross 308 broiler chicks was randomly allocated into 10 groups with 5 replicates (cages) of 8 chickens per replicate. Two of the groups, one challenged and the other not, were given a basal maize-soyabean meal diet without any additives; one of the challenged groups was administered a basal diet with the coccidiostat diclazuril (1 mg . kg(-1)) and the remaining birds of the infected groups were given a diet supplemented with one of the tested herbal extracts at a level of 750 mg . kg(-1). Throughout the 42 days of the experiment, performance parameters, mortality, oocyst output, and slaughter indices were recorded. Among the tested herbal extracts, in the first rearing period (9 d post infection), only garlic and sage extracts alleviated the negative effect of infection, as shown by the increase in body weight gain to the level recorded in the coccidiostat-supplemented group and, in the case of garlic extract, by lower mortality. In the second and entire experimental period, dietary supplementation with the herbal extracts improved the growth performance of infected chickens to the level obtained in the groups infected and fed the coccidiostat or the uninfected and unsupplemented ones, but there was no positive effect of extracts on oocyst output. It is concluded that the herbal extracts tested in the current study do not prevent coccidiosis induced by high-pathogenic field Eimeria spp., although they have a beneficial effect on recovery after infection, which was expressed by the favourable impact on compensatory growth and, thus, on the final performance indices.