5Wehrman M E, et al. Development of a persistent ovarian follicle and associated elevated concentrations of 17β- estradiol preceding ovulation does not alter the pregnancy rate afterembryo transfer in cattle. Theriogenology, 1997,47 : 1413 - 1421.
6Wolfsdorf K E, et al. The dominant follicle exerts an interovarian in- hibition on FSH- induced follicular development. Theriogenology, 1997,48:435 -447.
7Wiltbank J N, et al. Use of progestational compounda alone or in combination with estrogen for synchronization of estrus. J Anim Sci, 1965,24 : 990- 994.
8Dubey J P. Veterinary Parasitology,1999,84:349～367.
9Hong-Kean O, et al. Veterinary Parasitology,2000,90:47～55.
