title: Effect of follicular aspiration at the onset of progesterone-based timed artificial insemination on the follicular dynamics and fertility of early postpartum Japanese black cows.
abstract: The effect of gonadotropin-releasing hormone analogue (GnRH-A) or follicular aspiration at the onset of progesterone-based timed artificial insemination (TAI) on subsequent follicular growth and synchronization of ovulation was examined in early postpartum Japanese Black cows. A total of 40 (22 in Exp. 1 and 18 in Exp. 2) Japanese Black cows at 20-30 days postpartum were fitted with a progesterone releasing internal device (PRID) for 7 days, injected with a prostaglandin F2α analogue upon removal of the PRID and GnRH-A 48 h later, and inseminated 18 h after GnRH-A injection. In Exp. 1, the animals were divided into three groups (untreated control, GnRH-A injection or follicular aspiration) of different treatments on the first day of PRID insertion (day 0), and the synchronized ovulation rate in the follicular aspiration group (100%; 8/8) tended to be higher (P = 0.077) than that in the control group (42.9%; 3/7). In Exp. 2, follicular growth in the GnRH (n = 9) and follicular aspiration (n = 9) groups was monitored by ultrasonography. Four out of the nine animals in the GnRH group had a corpus luteum on either day 4 or day 7 (OV group), and the other five animals had no induced ovulation (NOV group). The diameter of the ovulatory follicle on day 9 in the OV group (1.44 ± 0.11 cm) tended to be greater (P = 0.078) than that in the NOV group (1.13 ± 0.07 cm). Follicular aspiration at the onset of PRID-based TAI of early postpartum Japanese Black cows, regardless of the resumption of ovarian cyclicity, tended to result in a higher rate of synchronization of ovulation than that of the untreated controls.
authors.affiliation: Faculty of Agriculture, Iwate University, Iwate 020-8550, Japan. hirata@iwate-u.ac.jp
authors.forename: Toh-Ichi
authors.initials: T
authors.lastname: Hirata
authors.forename: Naoki
authors.initials: N
authors.lastname: Kon
authors.forename: Akane
authors.initials: A
authors.lastname: Sugiyama
authors.forename: Mai
authors.initials: M
authors.lastname: Sato
authors.forename: Takeshi
authors.initials: T
authors.lastname: Osawa
mesh_terms: D000282:Administration, Intravaginal; D000818:Animals; D002417:Cattle / Q000378:metabolism / Q000502:physiology; D003116:Color; D004958:Estradiol / Q000097:blood; D004973:Estrus Synchronization / Q000097:blood / Q000379:methods*; D005260:Female; D005298:Fertility / Q000187:drug effects / Q000502:physiology*; D007987:Gonadotropin-Releasing Hormone / Q000097:blood; D007315:Insemination, Artificial / Q000379:methods* / Q000662:veterinary; D007436:Intrauterine Devices, Medicated; D054315:Oocyte Retrieval / Q000379:methods*; D006080:Ovarian Follicle / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D049590:Postpartum Period / Q000097:blood / Q000187:drug effects / Q000502:physiology; D011247:Pregnancy; D011374:Progesterone / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D013997:Time Factors
chemical_list: D007987:Gonadotropin-Releasing Hormone; D011374:Progesterone; D004958:Estradiol