Timing of ovulation after gonadotrophin induction and its importance to successful intrauterine insemination in the tiger (Panthera tigris).

The ovarian response to equine chorionic gonadotrophin (eCG) and human chorionic gonadotrophin (hCG), the effect of timing of ovulation relative to hCG injection and the use of laparoscopic intrauterine artificial insemination (AI) were examined in two subspecies of tiger (Panthera tigris). Adult female tigers were subjected to the same eCG/hCG treatment followed by laparoscopy under xylazine/diazapam/ketamine HCl anaesthesia at 39-42 h (Group I, n = 9), 46-49 h (Group II, n = 5) or 51-55 h (Group III, n = 5) after hCG. Six of these females, observed to be postovulatory at the time of laparoscopy (Group II, n = 3; Group III, n = 3), were subjected to intrauterine AI. The number of preovulatory follicles observed on the ovaries of Group I females was twofold greater (P < 0.05) than the number observed on ovaries of females in Group II and III. Fewer (P < 0.05) corpora lutea were observed on ovaries of Group I females (1.3 +/- 0.6) compared with the number of corpora lutea in Group II and III (combined average, 7.8 +/- 0.8 corpora lutea per female). Only one of ten females in Groups II and III failed to ovulate by the time of laparoscopy. Four Group I females never ovulated, based on a laparoscopic re-evaluation 4 weeks later. One female inseminated 46 h after hCG (Group II) became pregnant and delivered a healthy cub after a normal gestation. There were no apparent differences between subspecies in response to the same ovulation induction protocol. Results demonstrate the importance of the relationship between exogenous gonadotrophin treatment and onset of anaesthesia for laparoscopic examination and AI in tigers. Data clearly indicate that anaesthesia/laparoscopy conducted too early (39-42 h after hCG) compromises the number of females and proportion of follicles ovulating. In contrast, ovulation success is high if anaesthesia/laparoscopy is performed after this time, and intrauterine insemination can result in healthy young.