Comparing ovulation synchronization protocols for artificial insemination in the scimitar-horned oryx (Oryx dammah)

Ovarian response and pregnancy success in scimitar-homed oryx (n = 28) were compared, following treatment with two synchronization protocols and fixed -time artificial insemination (AI) with frozen-thawed semen. Each oryx rece ived two injections of 500 mu g of prostaglandin-F-2 alpha analogue (PGF(2 alpha)-only) 11 days apart, and half received PGF(2 alpha) in combination w ith an intravaginal progesterone-releasing device (CIDR11 + PGF(2 alpha)), Semen was collected by electroejaculation from anaesthetised adult oryx and cryopreserved. Anaesthetised females were transcervically inseminated 56.0 +/- 1.1 h (+/-S.E.M.) after PGF(2 alpha) injection and/or device withdrawa l using 28.0 +/- 1.5 x 10(6) motile thawed sperm. Ovarian endocrine respons e was monitored in 20 females by analysing faecal oestrogen and progesteron e metabolites. Periovulatory oestrogen peaks were detected in 19/20 (95%) f emales after synchronization. There were no between-treatment differences i n oestrogen concentrations or peak characteristics (P > 0.05). Luteal devel opment after synchronization was delayed in half the progesterone treated ( CIDR11 + PGF(2 alpha)) females, and faecal progestin excretion profiles ind icated that the ovulatory follicle associated with synchronization either f ailed to ovulate or to fully lutenise. Pregnancy was diagnosed by ultrasono graphy and/or rectal palpation and was monitored by faecal progestin excret ion. More (P = 0.013) pregnancies resulted from the PGF(2 alpha)-only treat ment (37.5%, 5/14) than from the CIDR11 + PGF(2 alpha) treatment (0/14), an d four healthy scimitar-horned oryx calves were born, three after gestation intervals of 247 days and one after 249 days. (C) 2000 Elsevier Science B. V. All rights reserved.