Tehran University of Medical Sciences Iranian Journal of Parasitology 1735-7020 8 3 2013 09 15 449 458 EN Jj Xu Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China. Cz Ren Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China. Ss Wang Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China. Dd Liu Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China. Lq Cao Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China. Jp Tao Ministry of Education Key Lab for Avian Preventive Medicine, Yangzhou University, Yangzhou, China. 2015 10 14   Background: To control avian coccidiosis with drug-independent strategy effec-tively and safely, multivalent hyperimmune egg yolk immunoglobulin (IgY) was prepared and its ability to protect against Eimeria tenella infection was evaluated. Methods: Hens were orally immunized with live oocysts of 5 species of Eimeria for six times, antibody titers in serum and yolk were monitored by indirect enzyme-linked immunosorbent assay. The specific IgY was isolated, purified and lyophi-lized. IgY powder was orally administrated as dietary supplement in newly hatched chicks at various dosages. Birds were orally challenged with 10000 sporulated oo-cysts of E. tenella at 10 days of age, weighed and killed at 8 days post challenge, and the protective effect was assessed. Results: The averge yeid of IgY was 9.2 mg/ml yolk, the antibody titer of IgY reached to 1:163840 per mg with the purity up to 98%. Chickens fed IgY resulted in reduced mortality, increased body weight gain (BWG), reduced oocyst shedding, reduced caecal lesion score and increased anti-coccidial index. In terms of BWG and caecal lesion, IgY significantly enhanced the resistance of bird at ≥ 0.05% of IgY in the diet when compared with the challenged control group (P<0.05). No significant difference was observed at dosage ≥ 0.5% and 1.0% when BWG and caecal lesion were compared with the sodium salinomycin control group, respec-tively (P>0.05). Conclusion: Supplementing newly hatched chicks with Eimeria-specific IgY repre-sents a promising strategy to prevent avian coccidiosis. https://ijpa.tums.ac.ir/index.php/ijpa/article/view/470 https://ijpa.tums.ac.ir/index.php/ijpa/article/download/470/496