CONCENTRATIONS OF FECAL IMMUNOREACTIVE PROGESTAGEN METABOLITES DURINGTHE ESTROUS-CYCLE AND PREGNANCY IN THE BLACK RHINOCEROS (DICEROS-BICORNIS-MICHAELI)

The analysis of reproductive hormones in faecal samples is a possibili ty for non-invasive monitoring of reproductive status in free-ranging or intractable species. In the present study, faecal samples from thre e black rhinoceroses (Diceros bicornis michaeli) were collected at abo ut weekly intervals during oestrous cycles and pregnancy. Daily sample s were taken during the week after parturition. Total immunoreactive p rogestagens in faecal extracts were analysed with three different enzy meimmunoassays (EIA) that had considerable specificity for progestagen s containing either a 20alpha-hydroxyl or a 20-keto group. With each E IA it was possible to distinguish between the follicular and luteal ph ases of the oestrous cycle. Mating corresponded with low concentration s of faecal progestagens. Samples from five and six consecutive cycles were available from two rhinoceroses and cycle lengths of 24 and 26.5 days were calculated. All three animals became pregnant and the durat ion of gestation ranged from 440 to 470 days. After fertilization, the concentration of progestagens increased continuously, as in the lutea l phase, reaching values 5-10 times higher between days 60 and 250. Du ring the two weeks before parturition faecal progestagens declined and within 3-4 days post partum had reached follicular phase values. It w as concluded that several immunoreactive progestagens are present in t he faeces of black rhinoceroses and that their measurement with EIA en ables non-invasive monitoring of the oestrous cycle and pregnancy.