Assessment of plant extracts on immune response, productive performance and intestinal morphometry of broilers challenged with Eimeria sp.

SUMMARY This study evaluated the effect of using plant extracts on immune response, productive performance, and intestinal morphometry of broilers challenged with coccidiosis vaccine. It was used 720 male Ross broiler chicks, distributed into a completely randomized design with four treatments and nine repetitions of 20 birds each. From the 14th day, animals received the following treatments: A - Basal diet + antibiotic growth promoter (AGP); B - Basal diet + AGP + vaccine challenge; C - Basal diet + plant extract and D - Basal diet + plant extract + vaccine challenge. Broilers of treatments B and D received oral coccidiosis vaccine (twenty times the label-recommended individual commercial dose). Adding plant extract to the diet of birds challenged with Eimeria sp increased (p <0.05) IgA secretion by the intestinal mucosa. Microscopic lesions of the intestinal mucosa were not affected (p> 0.05) by the immune challenge or addition of the plant extract. The challenge with oocysts of Eimeria sp or associated with the plant extract resulted in a smaller (p <0.05) weight gain and worse feed conversion only in the next week of the inoculation. The results showed that the addition of plant extracts to the diet of birds submitted to vaccine challenged increased the secretion of IgA by the intestinal mucosa and that the inclusion of the plant extract or of the antibiotic growth promoter resulted in similar productive performance at the age of slaughter.