Body temperature and physical activity correlates of the menstrual cycle in female chacma baboons (Papio hamadryas ursinus)

Nyakudya, Trevor Tapiwa
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I investigated the relationship between abdominal temperature, physical activity, anogenital swellings, and faecal and urine ovarian steroid hormonal concentrations over the menstrual cycle in baboons in an attempt to devise a reliable non-hormonal physiological indicator to detect ovulation. Using a miniature thermometric data logger surgically implanted in the abdominal cavity and an activity data logger implanted subcutaneously on the trunk, I measured, continuously over six months at a 10 min interval, abdominal temperature and physical activity patterns in four female adult baboons, Papio hamadryas ursinus (12.9-19.9 kg), unrestrained in cages in an indoor animal facility (22-25°C). I monitored menstrual bleeding, and anogenital swelling changes using digital photography, and collected urine and faeces, daily, to ascertain the stage and length of the menstrual cycle. The length of the menstrual cycle, determined from daily observations of menstrual bleeding and anogenital swellings, was 36 ± 2 days (mean ± SD). Baboons exhibited a cyclic change in anogenital swellings, abdominal temperature, physical activity, urine and faecal steroid hormones over the menstrual cycle. Mean 24-h abdominal temperature during the luteal phase was significantly higher (ANOVA, p = 0.04; F (2,9) = 4.7) than during the ovulatory phase, but not different to the follicular phase. Physical activity also followed a similar pattern, with mean 24 h physical activity almost twice as high in the luteal than in the ovulatory phase (ANOVA, p = 0.58; F (2,12) = 5.8). As expected, urine and faecal oestradiol was higher in the follicular than in the luteal phase, while progesterone was higher in the luteal than the follicular phase. Cortisol in both urine and faecal samples did not show any vi recognisable menstrual cycle related pattern. I have characterised correlates of the menstrual cycle in baboons and shown, for the first time, a rhythm of physical activity over the baboon menstrual cycle. I have also shown, from the measurements of abdominal temperature, physical activity, ovarian steroid hormonal concentrations and anogenital swellings, that ovulation in captive unrestrained baboons, and probably also free-living baboons, can be estimated from anogenital swellings or possibly abdominal temperature and physical activity, without the need for hormone measurements.
MSc (Med), Faculty of Health Sciences, University of the Witwatersrand
female baboons , menstrual cycle