Abstract:

In order to select the E.necatrix precocious line for the production of the attenuated vaccine. The pathogenic and reproduction of the precocious line and the parent strain were assessed by clinical situation, average weight gain, relative weight gain, lesion scores, the bloody stool scores, mortality, OPG, oocyst production and reproductive potential of oocyst reproduction index. The results showed that the precocious line was less pathogenic than the parent strains, the average weight gain, relative weight gain are higher, and the lesion scores, bloody scores and mortality were lower when compared with the parent strain. The peak of oviposition was advanced and total oocyst production of the precocious strain was depressed about 45% compared with that of parental strain, which fits the characteristics of the attenuated vaccine of the precocious line.