Eimeria praecox: selection and characteristics of precocious lines.

摘要: Summary Precocious lines of Eimeria praecox were obtained both from the Houghton laboratory strain and progeny a single sporocyst (derived strain) by selection for early development oocysts in mature host. The prepatent times parasites reduced 84 to less than 64 hours. evolution trait precocious appeared be step‐wise process culminating depletion of, probably, fourth generation schizont. Studies on line selected showed that it had multiplication rate 10% its parent strain, yet chickens given small numbers almost completely immune challenge with either or any one five field strains. was also slightly pathogenic. Examination sub‐line subjected 10 generations relaxed passage there no marked loss traits time fecundity.