Temporal Relationship Between Estrus, the Preovulatory LH Surge, and Ovulation in Fallow Deer

Abstract

To determine the precise timing of ovulation relative to the onset of estrus and the preovulatory LH surge in fallow deer (Dama dama), 20 (> 5 years old) does were allocated to two treatments designed to synchronize estrus on or about 17 May. Treatment 1 does (prostaglandin-induced estrus) received intravaginal progesterone-releasing devices for 13 days followed by an injection of 1500mg coprostenol on day 12 (15 May) of the subsequent estrous cycle. Treatment 2 does (progesterone-induced estrus) received CIDRs for a 13-day period, with withdrawal on 15 May. All does were run with crayon-harnessed bucks (10:1 ratio) from the start of synchronization treatment (1800h 15 May). Five does per treatment were blood sampled via in-dwelling jugular cannulae every 2h for 70 h from coprostenal administration/CIDR withdrawal, and the plasma was analyzed for LH. Does within each treatment were randomly allocated to one of four ovarian examination times (12, 16, 20, or 24h after onset of estrus). Laparoscopy was repeated at 12-h intervals until ovulation (hemorrhagic rupture point) was recorded.