Synchronization of oestrous cycles in sable antelope

Techniques for manipulating the oestrous cycle of sable antelope, Hippotragus niger, were evaluated in a captive population of 24 females maintained at the Smithsonian Institutionʹs Conservation and Research Center in Front Royal, VA, USA. A secondary objective was to demonstrate the effectiveness of fecal steroid monitoring techniques as a non-invasive method of tracking experimental manipulations. Controlled Internal Drug Releasing (CIDR) devices designed for cattle (type B, reduced in length by 5 cm to fit the sable antelopeʹs smaller reproductive tract) were more effective than CIDR devices designed for goats (type G) at delivering progesterone into circulation, and maintained serum progesterone at levels up to 86.1±7.8% of normal luteal concentrations in females whose spontaneous ovarian activity had been inhibited with melengestrol acetate. Serum progesterone and fecal progestagen measurements were highly correlated (P<0.05). Synchronization treatments of prostaglandin (PG) F2α alone and in combination with modified CIDR-B devices (12-day insertion interval) were both effective in inducing synchronized ovulation, however the PGF2α/modified CIDR-B treatment resulted in more precise synchrony and a shorter latency to ovulation than did PGF2α alone. In a separate experiment to characterize the temporal relationship between synchronization treatment, behavioral oestrus and ovulation, onset of behavioral oestrus occurred 34.1±5.7 h following PGF2α/modified CIDR-B treatment. Mean duration of the induced oestrus was 24.9±4.3 h. The first detectable rise in fecal progestagens occurred 5.1±1.0 and 4.1±1.0 days following PGF2α/modified CIDR-B treatment in groups of females housed with and without an adult male, respectively, indicating that the presence of a male did not accelerate the onset of the induced cycle.