Reproductive seasonality in the female scimitar-horned oryx (Oryx dammah)

Abstract

Faecal oestrogen and progestin analyses were used to assess ovarian activity in non-pregnant scimitar-horned oryx (Oryx dammah) during a 13-month interval. Mean (± SE) luteal phase, interluteal phase and oestrous cycle duration were 18.8 (± 0.5), 5.1 (± 0.2) and 23.8 (± 1.3) days, respectively. All females exhibited a synchronized anovulatory period that ranged from 36-95 days during spring. Short ovarian cycles (10.6 (± 0.8) days) were observed intermittently throughout the year and before the spontaneous resumption of oestrous cyclicity. Periovulatory peaks in oestrogen concentrations were detected for 42.5% (31/73) of ovarian cycles. A parallel analysis of reproductive data from the North American studbook (1985)(1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994) revealed that captive-held scimitar-horned oryx gave birth throughout the year. Sex ratio at birth was male-biased (54.4%), and 19.1% of all calves failed to survive to 6 months of age (220 out of 1149 births). Only 0.7% of births resulted in twins. Median interbirth interval was 277 days, and 75% of these intervals were less than 332 days. Interbirth interval was extended (P < 0.05) if parturition occurred from January through May. In summary, the scimitar-horned oryx is a seasonally polyoestrous species that experiences a distinct anovulatory period during spring in north-east America.

Endocrine patterns of the estrous cycle and pregnancy of wildebeest in the Serengeti ecosystem

“…The occurrence of recurring cyclic ovarian activity in cowseven while completely isolated from males-suggests that environmental cues are sufficient for annually up-regulating ovarian activity in wildebeest cows. This concurs with findings in other Bovidae (Sempere et al, 1996;Goodrowe et al, 1996;Thompson et al" 1998;Morrow et al, 1999;), but differs from the closest related species studied to date, the blesbok. Marais and Skinner (1993) found that female blesbok held in the presence of a male were polyestrous, whereas those in isolation remained anestrus until the introduction of a male.…”

“…Baseline values were determined by calculating the mean plus 1.5 standard deviations (Graham et al 1995;Morrow et al, 1999). Any value exceeding this criterion was considered elevated and removed from the set of nadir values.…”

“…Other than this information, there is a lack of fundamental data on reproductive physiology of Alcelaphinae with the exception of blesbok, which have been shown to be seasonally polyestrous (Marais and Skinner, 1993). Substantially greater basic knowledge has been generated for other wildlife species comprising the Bovidae subfamilies, including Antilopinae (Loskutoff et al, 1990;Penfold et al, 2005), Bovinae (Fogwell, 1999), Caprinae (Goodrowe et al, 1996), and Hippotraginae (Asa et al, 1996;Sempere et al, 1996;Thompson et al, 1998;Morrow et al, 1999). The common feature within these taxa is the significant variation in physiological function between species, thereby reinforcing the need to characterize each species of interest because ungulates have evolved substantially different reproductive mechanisms.…”

Reproductive seasonality in African ungulates in relation to rainfall

“…; Morrow et al 1999;Wronski et al 2011) and springbok (Antidorcas marsupialis; Skinner et al 2001) reproduce year-round.…”

<b>Non-Invasive Monitoring of Reproduction in Zoo and Wildlife Species</b>

“…Although germ cell production is less tightly coupled to hormonal variations in the male than in the female, non-invasive androgen monitoring in males has useful in characterizing seasonal patterns. Fecal and urinary steroid analysis has indicated seasonal influences on reproduction in females and/or males in several species, including the scimitar-horned oryx (Oryx dammah) (Morrow et al, 1999), the black-footed ferret (Mustela nigripes) (Brown, 1997), Maned wolves (Chrysocyon brachyurus) (Velloso et al, 1998), African wild dogs (Lycaon pictus) , Dalls sheep (Ovis dalli dalli) , Elds deer (Cervus eldi thamin) (Monfort et al, 1990) and Pere Davids deer (Elaphurus davidianus) . Once the relationship between steroid metabolite concentrations and reproductive events has been characterized for a species, non-invasive endocrine monitoring can be used as a tool to enhance the understanding and management of the species both in captivity and in the wild.…”