The Biological Characteristics Of Shihezi Stain Of Eimeria.mitis

The general biological Characteristics, endogenious development, pathogenicity, immunogenicity and sensitivity to currently used anticoccidials of Shihezi strain of E.mitis (code: E.mitis -SHZ)isolated from Shihezi county, Xinjiang Autonomous Region, China were studied.Oocysts of Shihezi strain of E.mitis, averaged 18.4μm²0.5μm, were larger than those of E. mitis described by any other researchers, with shape index of 1.11. The prepatent periods was 93 hours and the sporulation time was 16 hours at 28°C. The oocysts production approached to its peak between 113 hours¹21hours on the 5^th day PI (post infection).Developing trophozoites were found 28 hours PI in fresh smears, then the mature first-generation meronts were seen 32 hours PI. The mature and developing second-generation meronts parasitized all the way from the duodenum to the rectum and mainly in the upper and middle portions of the villi. Another types of small meronts , which might be the mature third-generation meronts, were observed between 72 hours and 76 hours PI. The later stages of endogenious development of E.mitis concentrated in the lower part of the small intestine, cecum and rectum. Mature oocysts with two layers of walls appeared in the ileum, cecum and rectum 93 hours PI,Results of cross immunity experiment of E.acervulina and E.mitis showed that the two Eimeria species could not induce cross immunity in chickens. The immunogenicity of E.mitis appeared to be stronger than that of Eacervulina. The complete and protective immunity could not be developed in chickens unless they were immunized with small numbers of oocysts of E.acervulina 2 or 3 times.E.mitis was less pathogenic than E.tenella ,E.necatrix and E.brunetti, however the skank skin pigment of the leg and beak of the young chickens were lost and weight gains were reduced during heavy infections with E.mitis. The middle and lower small intestine became thin and pale, but the discharged feces appeared normal. OPG for Chickens, immunized with 1 000 oocysts of E.mitis and then challenged with 200 000 sporulated oocysts of E.mitis, was...