Fecal corticoid profiles and their influence on the reproductive status of the female southern white rhinoceroses (Ceratotherium simum simum)
Keyzer, K. de
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Reproduction rate in captive southern white rhinoceroses is astonishingly low and the reason for this remains unclear. In this study fecal corticoid and progesterone profiles were obtained of two female white rhinoceroses living in the Khao Kheow Open Zoo, Thailand, that never produced offspring. Goal was to study the relationship between stress and fertility. Mean fecal corticoid concentrations were 36.2 ng/g and 37.9 ng/g, corticoid variability was 29.1 and 30.9. There was no strong correlation between fecal cortisol and progesterone concentrations (r=0.4). The progesterone profiles were not indicative of acyclicity, suggesting cortisol does not inhibit cyclicity in these animals. Average cycle length based on behavioral observation was 26 days, with no obvious irregularity observed. However, the period of sample taking is too short to draw conclusions about regularity of cycle length. To determine whether cortisol prevents successful pregnancy, further research is necessary, including ultrasonography and long-term hormonal profiles.