Phytogenics to prevent chicken coccidiosis

Coccidiosis of farm animals is mainly caused by the apicomplexan parasite Eimeria. The disease has substantial impact on animal production economy, health and welfare. Anticoccidial drugs are preventively used in poultry feed, with the associated problems of emerging parasite resistance and residues in animal products. As an alternative, plant-derived extracts and pure compounds were studied in vitro for parasite inhibition. Among several active samples, thyme extracts and thymol had specific anti-eimerial effects, but carvacrol did not. Challenge trials using monospecific or multi-species infections of broiler chicken showed slight improvement of coccidiosis symptoms when pure thymol was added to the diet. Two types of encapsulated thymol however protected effectively against disease-associated weight loss, feed malabsorption and mortality. Parasite shedding and intestinal lesions were also reduced, though not to the same extent as by the anticoccidial drug lasalocid. Functional feed additives of plant origin (phytogenics) show potential to alleviate coccidiosis. Antiparasitic effects of thymol were not as strong as those exerted by lasalocid, but efficacy may be increased by improving product formulation.