Endocrine correlates of female reproductive activity in the roan antelope (Hippotragus equinus)
Although ovarian endocrine activity has been described in most members of the tribe Hippotragini, little is known about the reproductive physiology of the roan antelope (Hippotragus equinus), an endangered antelope species in southern Africa. This study aimed to characterise the endocrine pattern of the oestrous cycle, pregnancy and post-partum period in the species by monitoring faecal progestagen (fPM) and oestrogen metabolite (fEM) concentrations and performing behavioural observations. Eighteen captive females were monitored for 12 months during this study, with individual faecal sampling taking place three times per week during the presumed period of cyclicity, twice per week during pregnancy and daily for 21 days post-partum. The females were observed during mating and calving periods, and courtship events, copulations and births were recorded when noted. Eight of the 18 females monitored showed an oestrous cycle with a distinctive follicular and luteal phase. Patterns of fPM and fEM concentrations indicated an oestrous cycle length of 31.1 ± 1.3 days in multiparous females (n=5), 37 ± 1.4 days in nulliparous females (n=2) and 16.0 days in a primiparous aminal (n=1). The determined length of luteal and follicular phases were 14.0 ± 0.7 days and 16.0 ± 2.4 days in length in multiparous females, 17.1 ± 1.1 days and 16.8 ± 2.2 days in nulliparous females, and 9.0 days and 6.0 days for the primiparous female. Pregnancy was marked by a pronounced increase in fPM concentrations until parturition and lasted approximately 280.4 ± 4.8 days; whereas the intercalving period ranged between 306 and 380 days (mean: 333.2 ± 7.4 days). Twenty-one days after parturition, 78% of the focal females did not show a resumption of the ovarian activity. The present study demonstrated that monitoring faecal reproductive hormone metabolite patterns is a valuable approach for estimating ovarian activity in roan antelope and may be used to assist respective conservation breeding programmes by improving management practices.