Establishment Of Eimeria Single-oocyst Isolating Technique And Study On The Pathogenicity And Drug Resistance Of Yangling Strains

chicken Eimeria have 9 species, are almost universally found wherever chickens are raised and often result in significantly economic loss. Concurrent infection with two or more species of Eimeria is common. The most pathogenic species are E.tenella and E.necatrix in chickens. A new Eimeria single-oocyst isolating technique was established by using a agar board method.2 kinds of Eimeria geography strain were obtained by using this technique, namely Yangling strain of E.tenella (YLt) and Yangling strain of E.necatrix (YLn), respectively. At the same time, the assay of the pathogenicity and drug resistance of YLt and YLn were conducted. The results showed that the new technique is easy to operate and has a 40% rate of success. This new technique is very important to further study on the pathogenicity and drug resistance in chicken Eimeria. YLt oocyst is broadly ovoid, size (20.6+3.29)umx(17.5+2.47)um with a smooth, brown wall, shape index of 1.17+0.05, without a micropyle, sporocyst residuum and oocyst residuum, with a polar granule. The sporocysts are oblong ovoid with stieda body. The sporulatic time is 28 h. The minimum prepatent periods is 118 h. YLn oocyst is ellipsoid or spherical, size (19.0+1.44)um(16.4+2.49)um with a rough, deep brown or Kelly thick wall, shape index of 1.16+0.06, without a micropyle, sporocyst residuum and oocyst residuum, with a polar granule. The sporocysts are ovoid with stieda body. The sporulatic time is 24 h. The minimum prepatent periods is 138 h. YLt and YLn are both high pathogenic, and their relative weight gain rates can fall 33.5% and 36.4%, the lesion score can reach 3.5 and 3.2, the mortality to chickens can reach as high as 60.6% and 64.3%, respectively, when chickens are inoculated with a dosage of 1 X 105 sporulated oocysts each bird. Four grades of the sensitivity of drugs, including sensitive (S), light resistant (LR), middle resistant (MR) and complete resistant (CR), were assessed by relative oocyst production (ROP), reduction of lesion scores (RLS), percent of optimum anticoccidial activity (POAA), and anticoccidial index (ACI). The experiment results revealed that resistance of YLt and YLn to different drugs had similar result. They were completely resistant to Diclazuril, ligh resistant to Maduramicin, sensitive to Clopidol and Robenidine. YLt and YLn were light resistant or complete resistant to Maduramicin, Diclazuril and Zoalene. Therefore, the coccidiosis couldn't be controlled with these drugs, and high sensitive to Clopidol and Robenidine. Mean body weight gains of chicken with Robenidine group was higher than that of Clopidol group,however, Robenidine was recommended to select firstly in practical application in Yangling.